Java-j2ee
Is it possible to communicate from an applet to servlet and how many ways and how?- Yes, there are three ways to communicate from an applet to servlet and they are: a) HTTP Communication(Text-based and object-based) b) Socket Communication c) RMI Communication
What is connection pooling?- With servlets, opening a database connection is a major bottleneck because we are creating and tearing down a new connection for every page request and the time taken to create connection will be more. Creating a connection pool is an ideal approach for a complicated servlet. With a connection pool, we can duplicate only the resources we need to duplicate rather than the entire servlet. A connection pool can also intelligently manage the size of the pool and make sure each connection remains valid. A number of connection pool packages are currently available. Some like DbConnectionBroker are freely available from Java Exchange Works by creating an object that dispenses connections and connection Ids on request. The ConnectionPool class maintains a Hastable, using Connection objects as keys and Boolean values as stored values. The Boolean value indicates whether a connection is in use or not. A program calls getConnection() method of the ConnectionPool for getting Connection object it can use; it calls returnConnection() to give the connection back to the pool.
Why should we go for interservlet communication?- Servlets running together in the same server communicate with each other in several ways. The three major reasons to use interservlet communication are: a) Direct servlet manipulation - allows to gain access to the other currently loaded servlets and perform certain tasks (through the ServletContext object) b) Servlet reuse - allows the servlet to reuse the public methods of another servlet. c) Servlet collaboration - requires to communicate with each other by sharing specific information (through method invocation)
Is it possible to call servlet with parameters in the URL?- Yes. You can call a servlet with parameters in the syntax as (?Param1 = xxx || m2 = yyy).
What is Servlet chaining?- Servlet chaining is a technique in which two or more servlets can cooperate in servicing a single request. In servlet chaining, one servlet’s output is piped to the next servlet’s input. This process continues until the last servlet is reached. Its output is then sent back to the client.
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How do servlets handle multiple simultaneous requests?- The server has multiple threads that are available to handle requests. When a request comes in, it is assigned to a thread, which calls a service method (for example: doGet(), doPost() and service()) of the servlet. For this reason, a single servlet object can have its service methods called by many threads at once.
What is Inet address?- Every computer connected to a network has an IP address. An IP address is a number that uniquely identifies each computer on the Net. An IP address is a 32-bit number.
What is Domain Naming Service(DNS)?- It is very difficult to remember a set of numbers(IP address) to connect to the Internet. The Domain Naming Service(DNS) is used to overcome this problem. It maps one particular IP address to a string of characters. For example, www. mascom. com implies com is the domain name reserved for US commercial sites, moscom is the name of the company and www is the name of the specific computer, which is mascom’s server.
What is URL?- URL stands for Uniform Resource Locator and it points to resource files on the Internet. URL has four components: http://www. address. com:80/index.html, where http - protocol name, address - IP address or host name, 80 - port number and index.html - file path.
What is RMI and steps involved in developing an RMI object?- Remote Method Invocation (RMI) allows java object that executes on one machine and to invoke the method of a Java object to execute on another machine. The steps involved in developing an RMI object are: a) Define the interfaces b) Implementing these interfaces c) Compile the interfaces and their implementations with the java compiler d) Compile the server implementation with RMI compiler e) Run the RMI registry f) Run the application
What is RMI architecture?- RMI architecture consists of four layers and each layer performs specific functions: a) Application layer - contains the actual object definition. b) Proxy layer - consists of stub and skeleton. c) Remote Reference layer - gets the stream of bytes from the transport layer and sends it to the proxy layer. d) Transportation layer - responsible for handling the actual machine-to-machine communication.
what is UnicastRemoteObject?- All remote objects must extend UnicastRemoteObject, which provides functionality that is needed to make objects available from remote machines.
Explain the methods, rebind() and lookup() in Naming class?- rebind() of the Naming class(found in java. rmi) is used to update the RMI registry on the server machine. Naming. rebind(”AddSever”, AddServerImpl); lookup() of the Naming class accepts one argument, the rmi URL and returns a reference to an object of type AddServerImpl.
What is a Java Bean?- A Java Bean is a software component that has been designed to be reusable in a variety of different environments.
What is a Jar file?- Jar file allows to efficiently deploying a set of classes and their associated resources. The elements in a jar file are compressed, which makes downloading a Jar file much faster than separately downloading several uncompressed files. The package java. util. zip contains classes that read and write jar files.
What is BDK?- BDK, Bean Development Kit is a tool that enables to create, configure and connect a set of set of Beans and it can be used to test Beans without writing a code.
What is JSP?- JSP is a dynamic scripting capability for web pages that allows Java as well as a few special tags to be embedded into a web file (HTML/XML, etc). The suffix traditionally ends with .jsp to indicate to the web server that the file is a JSP files. JSP is a server side technology - you can’t do any client side validation with it. The advantages are: a) The JSP assists in making the HTML more functional. Servlets on the other hand allow outputting of HTML but it is a tedious process. b) It is easy to make a change and then let the JSP capability of the web server you are using deal with compiling it into a servlet and running it.
What are JSP scripting elements?- JSP scripting elements lets to insert Java code into the servlet that will be generated from the current JSP page. There are three forms: a) Expressions of the form <%= expression %> that are evaluated and inserted into the output, b) Scriptlets of the form<% code %>that are inserted into the servlet’s service method, and c) Declarations of the form <%! Code %>that are inserted into the body of the servlet class, outside of any existing methods.
What are JSP Directives?- A JSP directive affects the overall structure of the servlet class. It usually has the following form:<%@ directive attribute=”value” %> However, you can also combine multiple attribute settings for a single directive, as follows:<%@ directive attribute1=”value1? attribute 2=”value2? . . . attributeN =”valueN” %> There are two main types of directive: page, which lets to do things like import classes, customize the servlet superclass, and the like; and include, which lets to insert a file into the servlet class at the time the JSP file is translated into a servlet
What are Predefined variables or implicit objects?- To simplify code in JSP expressions and scriptlets, we can use eight automatically defined variables, sometimes called implicit objects. They are request, response, out, session, application, config, pageContext, and page.
What are JSP ACTIONS?- JSP actions use constructs in XML syntax to control the behavior of the servlet engine. You can dynamically insert a file, reuse JavaBeans components, forward the user to another page, or generate HTML for the Java plugin. Available actions include: jsp:include - Include a file at the time the page is requested. jsp:useBean - Find or instantiate a JavaBean. jsp:setProperty - Set the property of a JavaBean. jsp:getProperty - Insert the property of a JavaBean into the output. jsp:forward - Forward the requester to a newpage. Jsp: plugin - Generate browser-specific code that makes an OBJECT or EMBED
How do you pass data (including JavaBeans) to a JSP from a servlet?- (1) Request Lifetime: Using this technique to pass beans, a request dispatcher (using either “include” or forward”) can be called. This bean will disappear after processing this request has been completed. Servlet: request. setAttribute(”theBean”, myBean); RequestDispatcher rd = getServletContext(). getRequestDispatcher(”thepage. jsp”); rd. forward(request, response); JSP PAGE:(2) Session Lifetime: Using this technique to pass beans that are relevant to a particular session (such as in individual user login) over a number of requests. This bean will disappear when the session is invalidated or it times out, or when you remove it. Servlet: HttpSession session = request. getSession(true); session. putValue(”theBean”, myBean); /* You can do a request dispatcher here, or just let the bean be visible on the next request */ JSP Page: 3) Application Lifetime: Using this technique to pass beans that are relevant to all servlets and JSP pages in a particular app, for all users. For example, I use this to make a JDBC connection pool object available to the various servlets and JSP pages in my apps. This bean will disappear when the servlet engine is shut down, or when you remove it. Servlet: GetServletContext(). setAttribute(”theBean”, myBean); JSP PAGE:
How can I set a cookie in JSP?- response. setHeader(”Set-Cookie”, “cookie string”); To give the response-object to a bean, write a method setResponse (HttpServletResponse response) - to the bean, and in jsp-file:<% bean. setResponse (response); %>
How can I delete a cookie with JSP?- Say that I have a cookie called “foo, ” that I set a while ago & I want it to go away. I simply: <% Cookie killCookie = new Cookie(”foo”, null); KillCookie. setPath(”/”); killCookie. setMaxAge(0); response. addCookie(killCookie); %>
How are Servlets and JSP Pages related?- JSP pages are focused around HTML (or XML) with Java codes and JSP tags inside them. When a web server that has JSP support is asked for a JSP page, it checks to see if it has already compiled the page into a servlet. Thus, JSP pages become servlets and are transformed into pure Java and then compiled, loaded into the server and executed.
MAINFRAME
) Name the divisions in a COBOL program ?.
A1) IDENTIFICATION DIVISION, ENVIRONMENT DIVISION, DATA DIVISION, PROCEDURE DIVISION.
Q2) What are the different data types available in COBOL?
A2) Alpha-numeric (X), alphabetic (A) and numeric (9).
Q3) What does the INITIALIZE verb do? - GS
A3) Alphabetic, Alphanumeric fields & alphanumeric edited items are set to SPACES. Numeric, Numeric edited items set to ZERO. FILLER , OCCURS DEPENDING ON items left untouched.
Q4) What is 77 level used for ?
A4) Elementary level item. Cannot be subdivisions of other items (cannot be qualified), nor can they be subdivided themselves.
Q5) What is 88 level used for ?
A5) For condition names.
Q6) What is level 66 used for ?
A6) For RENAMES clause.
Q7) What does the IS NUMERIC clause establish ?
A7) IS NUMERIC can be used on alphanumeric items, signed numeric & packed decimal items and unsigned numeric & packed decimal items. IS NUMERIC returns TRUE if the item only consists of 0-9. However, if the item being tested is a signed item, then it may contain 0-9, + and - .
Q8) How do you define a table/array in COBOL?
A8) ARRAYS.
05 ARRAY1 PIC X(9) OCCURS 10 TIMES.
05 ARRAY2 PIC X(6) OCCURS 20 TIMES INDEXED BY WS-INDEX.
Q9) Can the OCCURS clause be at the 01 level?
A9) No.
Q10) What is the difference between index and subscript? - GS
A10) Subscript refers to the array occurrence while index is the displacement (in no of bytes) from the beginning of the
array. An index can only be modified using PERFORM, SEARCH & SET. Need to have index for a table in order to
use SEARCH, SEARCH ALL.
Q11) What is the difference between SEARCH and SEARCH ALL? - GS
A11) SEARCH - is a serial search.
SEARCH ALL - is a binary search & the table must be sorted ( ASCENDING/DESCENDING KEY clause to be used & data loaded in this order) before using SEARCH ALL.
Q12) What should be the sorting order for SEARCH ALL? - GS
A12) It can be either ASCENDING or DESCENDING. ASCENDING is default. If you want the search to be done on an
array sorted in descending order, then while defining the array, you should give DESCENDING KEY clause. (You
must load the table in the specified order).
Q13) What is binary search?
A13) Search on a sorted array. Compare the item to be searched with the item at the center. If it matches, fine else repeat the process with the left half or the right half depending on where the item lies.
Q14) My program has an array defined to have 10 items. Due to a bug, I find that even if the program access the
11th item in this array, the program does not abend. What is wrong with it?
A14) Must use compiler option SSRANGE if you want array bounds checking. Default is NOSSRANGE.
Q15) How do you sort in a COBOL program? Give sort file definition, sort statement syntax and meaning. - GS
A15) Syntax: SORT file-1 ON ASCENDING/DESCENDING KEY key.... USING file-2 GIVING file-3.
USING can be substituted by INPUT PROCEDURE IS para-1 THRU para-2
GIVING can be substituted by OUTPUT PROCEDURE IS para-1 THRU para-2.
file-1 is the sort (work) file and must be described using SD entry in FILE SECTION.
file-2 is the input file for the SORT and must be described using an FD entry in FILE SECTION and SELECT
clause in FILE CONTROL.
file-3 is the out file from the SORT and must be described using an FD entry in FILE SECTION and SELECT
clause in FILE CONTROL.
file-1, file-2 & file-3 should not be opened explicitly.
INPUT PROCEDURE is executed before the sort and records must be RELEASEd to the sort work file from the input procedure.
OUTPUT PROCEDURE is executed after all records have been sorted. Records from the sort work file must be RETURNed one at a time to the output procedure.
Q16) How do you define a sort file in JCL that runs the COBOL program?
A16) Use the SORTWK01, SORTWK02,..... dd names in the step. Number of sort datasets depends on the volume of data
being sorted, but a minimum of 3 is required.
Q17) What is the difference between performing a SECTION and a PARAGRAPH? - GS
A17) Performing a SECTION will cause all the paragraphs that are part of the section, to be performed.
Performing a PARAGRAPH will cause only that paragraph to be performed.
Q18) What is the use of EVALUATE statement? - GS
A18) Evaluate is like a case statement and can be used to replace nested Ifs. The difference between EVALUATE and
case is that no 'break' is required for EVALUATE i.e. control comes out of the EVALUATE as soon as one match is
made.
Q19) What are the different forms of EVALUATE statement?
A19)
EVALUATE EVALUATE SQLCODE ALSO FILE-STATUS
WHEN A=B AND C=D WHEN 100 ALSO '00'
imperative stmt imperative stmt
WHEN (D+X)/Y = 4 WHEN -305 ALSO '32'
imperative stmt imperative stmt
WHEN OTHER WHEN OTHER
imperative stmt imperative stmt
END-EVALUATE END-EVALUATE
EVALUATE SQLCODE ALSO A=B EVALUATE SQLCODE ALSO TRUE
WHEN 100 ALSO TRUE WHEN 100 ALSO A=B
imperative stmt imperative stmt
WHEN -305 ALSO FALSE WHEN -305 ALSO (A/C=4)
imperative stmt imperative stmt
END-EVALUATE END-EVALUATE
Q20) How do you come out of an EVALUATE statement? - GS
A20) After the execution of one of the when clauses, the control is automatically passed on to the next sentence after the
EVALUATE statement. There is no need of any extra code.
Q21) In an EVALUATE statement, can I give a complex condition on a when clause?
A21) Yes.
Q22) What is a scope terminator? Give examples.
A22) Scope terminator is used to mark the end of a verb e.g. EVALUATE, END-EVALUATE; IF, END-IF.
Q23) How do you do in-line PERFORM? - GS
A23) PERFORM ... ...
END-PERFORM
Q24) When would you use in-line perform?
A24) When the body of the perform will not be used in other paragraphs. If the body of the perform is a generic type of code
(used from various other places in the program), it would be better to put the code in a separate Paraand use
PERFORM Para name rather than in-line perform.
Q25) What is the difference between CONTINUE & NEXT SENTENCE ?
A25) They appear to be similar, that is, the control goes to the next sentence in the paragraph. But, Next Sentence would
take the control to the sentence after it finds a full stop (.). Check out by writing the following code example, one if
sentence followed by 3 display statements (sorry they appear one line here because of formatting restrictions) If 1 > 0
then next sentence end if display 'line 1' display 'line 2'. display 'line 3'. *** Note- there is a dot (.) only at the end of
the last 2 statements, see the effect by replacing Next Sentence with Continue ***
Q26) What does EXIT do ?
A26) Does nothing ! If used, must be the only sentence within a paragraph.
Q27) Can I redefine an X(100) field with a field of X(200)?
A27) Yes. Redefines just causes both fields to start at the same location. For example:
01 WS-TOP PIC X(1)
01 WS-TOP-RED REDEFINES WS-TOP PIC X(2).
If you MOVE '12' to WS-TOP-RED,
DISPLAY WS-TOP will show 1 while
DISPLAY WS-TOP-RED will show 12.
Q28) Can I redefine an X(200) field with a field of X(100) ?
A31) Yes.
Q31) What do you do to resolve SOC-7 error? - GS
A31) Basically you need to correcting the offending data. Many times the reason for SOC7 is an un-initialized numeric item.
Examine that possibility first. Many installations provide you a dump for run time abend’s ( it can be generated also
by calling some subroutines or OS services thru assembly language). These dumps provide the offset of the last
instruction at which the abend occurred. Examine the compilation output XREF listing to get the verb and the line
number of the source code at this offset. Then you can look at the source code to find the bug. To get capture the
runtime dumps, you will have to define some datasets (SYSABOUT etc ) in the JCL. If none of these are helpful, use
judgement and DISPLAY to localize the source of error. Some installation might have batch program debugging
tools. Use them.
Q32) How is sign stored in Packed Decimal fields and Zoned Decimal fields?
A32) Packed Decimal fields: Sign is stored as a hex value in the last nibble (4 bits ) of the storage.
Zoned Decimal fields: As a default, sign is over punched with the numeric value stored in the last bite.
Q33) How is sign stored in a comp-3 field? - GS
A33) It is stored in the last nibble. For example if your number is +100, it stores hex 0C in the last byte, hex 1C if
your number is 101, hex 2C if your number is 102, hex 1D if the number is -101, hex 2D if the number is –102 etc...
Q34) How is sign stored in a COMP field ? - GS
A34) In the most significant bit. Bit is ON if -ve, OFF if +ve.
Q35) What is the difference between COMP & COMP-3 ?
A35) COMP is a binary storage format while COMP-3 is packed decimal format.
Q36) What is COMP-1? COMP-2?
A36) COMP-1 - Single precision floating point. Uses 4 bytes.
COMP-2 - Double precision floating point. Uses 8 bytes.
Q37) How do you define a variable of COMP-1? COMP-2?
A37) No picture clause to be given. Example 01 WS-VAR USAGE COMP-1.
Q38) How many bytes does a S9(7) COMP-3 field occupy ?
A38) Will take 4 bytes. Sign is stored as hex value in the last nibble. General formula is INT((n/2) + 1)), where n=7 in this
example.
Q39) How many bytes does a S9(7) SIGN TRAILING SEPARATE field occupy ?
A39) Will occupy 8 bytes (one extra byte for sign).
Q40) How many bytes will a S9(8) COMP field occupy ?
A40) 4 bytes.
Q41) What is the maximum value that can be stored in S9(8) COMP?
A41) 99999999
Q42) What is COMP SYNC?
A42) Causes the item to be aligned on natural boundaries. Can be SYNCHRONIZED LEFT or RIGHT. For binary data
items, the address resolution is faster if they are located at word boundaries in the memory. For example, on main
frame the memory word size is 4 bytes. This means that each word will start from an address divisible by 4. If my
first variable is x(3) and next one is s9(4) comp, then if you do not specify the SYNC clause, S9(4) COMP will start
from byte 3 ( assuming that it starts from 0 ). If you specify SYNC, then the binary data item will start from address 4.
You might see some wastage of memory, but the access to this computational field is faster.
Q43) What is the maximum size of a 01 level item in COBOL I? in COBOL II?
A43) In COBOL II: 16777215
Q44) How do you reference the following file formats from COBOL programs:
A44)
Fixed Block File - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS F,
BLOCK CONTAINS 0 .
Fixed Unblocked - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS F,
do not use BLOCK CONTAINS
Variable Block File - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS V, BLOCK
CONTAINS 0. Do not code the 4 bytes for record length in FD ie JCL reclength will be max rec length in pgm + 4
Variable Unblocked - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS V, do not use
BLOCK CONTAINS. Do not code 4 bytes for record length in FD ie JCL reclength will
be max rec length in pgm + 4.
ESDS VSAM file - Use ORGANISATION IS SEQUENTIAL.
KSDS VSAM file - Use ORGANISATION IS INDEXED, RECORD KEY IS, ALTERNATE RECORD KEY IS RRDS File - Use ORGANISATION IS RELATIVE, RELATIVE KEY IS
Printer File - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS F, BLOCK
CONTAINS 0. (Use RECFM=FBA in JCL DCB).
Q45) What are different file OPEN modes available in COBOL?
A45) Open for INPUT, OUTPUT, I-O, EXTEND.
Q46) What is the mode in which you will OPEN a file for writing? - GS
A46) OUTPUT, EXTEND
Q47) In the JCL, how do you define the files referred to in a subroutine ?
A47) Supply the DD cards just as you would for files referred to in the main program.
Q48) Can you REWRITE a record in an ESDS file? Can you DELETE a record from it?
A48) Can rewrite (record length must be same), but not delete.
Q49) What is file status 92? - GS
A49) Logic error. e.g., a file is opened for input and an attempt is made to write to it.
Q50) What is file status 39 ?
A50) Mismatch in LRECL or BLOCKSIZE or RECFM between your COBOL pgm & the JCL (or the dataset label). You
will get file status 39 on an OPEN.
Q51) What is Static and Dynamic linking ?
A51) In static linking, the called subroutine is link-edited into the calling program , while in dynamic linking, the subroutine
& the main program will exist as separate load modules. You choose static/dynamic linking by choosing either the
DYNAM or NODYNAM link edit option. (Even if you choose NODYNAM, a CALL identifier (as opposed to a
CALL literal), will translate to a DYNAMIC call).
A statically called subroutine will not be in its initial state the next time it is called unless you explicitly use INITIAL
or you do a CANCEL. A dynamically called routine will always be in its initial state.
Q52) What is AMODE(24), AMODE(31), RMODE(24) and RMODE(ANY)? (applicable to only MVS/ESA
Enterprise Server).
A52) These are compile/link edit options. Basically AMODE stands for Addressing mode and RMODE for Residency
mode.
AMODE(24) - 24 bit addressing;
AMODE(31) - 31 bit addressing
AMODE(ANY) - Either 24 bit or 31 bit addressing depending on RMODE.
RMODE(24) - Resides in virtual storage below 16 Meg line. Use this for 31 bit programs that call 24 bit programs.
(OS/VS Cobol pgms use 24 bit addresses only).
RMODE(ANY) - Can reside above or below 16 Meg line.
Q53) What compiler option would you use for dynamic linking?
A53) DYNAM.
Q54) What is SSRANGE, NOSSRANGE ?
A54) These are compiler options with respect to subscript out of range checking. NOSSRANGE is the default and if chosen,
no run time error will be flagged if your index or subscript goes out of the permissible range.
Q55) How do you set a return code to the JCL from a COBOL program?
A55) Move a value to RETURN-CODE register. RETURN-CODE should not be declared in your program.
Q56) How can you submit a job from COBOL programs?
A56) Write JCL cards to a dataset with //xxxxxxx SYSOUT= (A,INTRDR) where 'A' is output class, and dataset should be
opened for output in the program. Define a 80 byte record layout for the file.
Q57) What are the differences between OS VS COBOL and VS COBOL II?
A57) OS/VS Cobol pgms can only run in 24 bit addressing mode, VS Cobol II pgms can run either in 24 bit or 31 bit
addressing modes.
I. Report writer is supported only in OS/VS Cobol.
II. USAGE IS POINTER is supported only in VS COBOL II.
III. Reference modification e.g.: WS-VAR(1:2) is supported only in VS COBOL II.
IV. EVALUATE is supported only in VS COBOL II.
V. Scope terminators are supported only in VS COBOL II.
VI. OS/VS Cobol follows ANSI 74 stds while VS COBOL II follows ANSI 85 stds.
VII. Under CICS Calls between VS COBOL II programs are supported.
Q58) What are the steps you go through while creating a COBOL program executable?
A58) DB2 precompiler (if embedded SQL used), CICS translator (if CICS pgm), Cobol compiler, Link editor. If DB2
program, create plan by binding the DBRMs.
Q59) Can you call an OS VS COBOL pgm from a VS COBOL II pgm ?
A59) In non-CICS environment, it is possible. In CICS, this is not possible.
Q60) What are the differences between COBOL and COBOL II?
A60) There are at least five differences:
COBOL II supports structured programming by using in line Performs and explicit scope terminators, It introduces
new features (EVALUATE, SET. TO TRUE, CALL. BY CONTEXT, etc) It permits programs to be loaded and
addressed above the 16-megabyte line It does not support many old features (READY TRACE, REPORT-WRITER,
ISAM, Etc.), and It offers enhanced CICS support.
Q61) What is an explicit scope terminator?
A61) A scope terminator brackets its preceding verb, e.g. IF .. END-IF, so that all statements between the verb and its scope terminator are grouped together. Other common COBOL II verbs are READ, PERFORM, EVALUATE, SEARCH and STRING.
Q62) What is an in line PERFORM? When would you use it? Anything else to say about it?
A62) The PERFORM and END-PERFORM statements bracket all COBOL II statements between them. The COBOL equivalent is to PERFORM or PERFORM THRU a paragraph. In line PERFORMs work as long as there are no internal GO TOs, not even to an exit. The in line PERFORM for readability should not exceed a page length - often it will reference other PERFORM paragraphs.
Q63) What is the difference between NEXT SENTENCE and CONTINUE?
A63) NEXT SENTENCE gives control to the verb following the next period. CONTINUE gives control to the next verb after the explicit scope terminator. (This is not one of COBOL II's finer implementations). It's safest to use CONTINUE rather than NEXT SENTENCE in COBOL II.
Q64) What COBOL construct is the COBOL II EVALUATE meant to replace?
A64) EVALUATE can be used in place of the nested IF THEN ELSE statements.
Q65) What is the significance of 'above the line' and 'below the line'?
A65) Before IBM introduced MVS/XA architecture in the 1980's a program's virtual storage was limited to 16 megs. Programs compiled with a 24 bit mode can only address 16 Mb of space, as though they were kept under an imaginary storage line. With COBOL II a program compiled with a 31 bit mode can be 'above the 16 Mb line. (This 'below the line', 'above the line' imagery confuses most mainframe programmers, who tend to be a literal minded group.)
Q66) What was removed from COBOL in the COBOL II implementation?
A66) Partial list: REMARKS, NOMINAL KEY, PAGE-COUNTER, CURRENT-DAY, TIME-OF-DAY, STATE, FLOW, COUNT, EXAMINE, EXHIBIT, READY TRACE and RESET TRACE.
Q67) Explain call by context by comparing it to other calls.
A67) The parameters passed in a call by context are protected from modification by the called program. In a normal call they are able to be modified.
Q68) What is the linkage section?
A68) The linkage section is part of a called program that 'links' or maps to data items in the calling program's working storage. It is the part of the called program where these share items are defined.
Q69) What is the difference between a subscript and an index in a table definition?
A69) A subscript is a working storage data definition item, typically a PIC (999) where a value must be moved to the subscript and then incremented or decrements by ADD TO and SUBTRACT FROM statements. An index is a register item that exists outside the program's working storage. You SET an index to a value and SET it UP BY value and DOWN BY value.
Q70) If you were passing a table via linkage, which is preferable - a subscript or an index?
A70) Wake up - you haven't been paying attention! It's not possible to pass an index via linkage. The index is not part of the calling programs working storage. Those of us who've made this mistake, appreciate the lesson more than others.
Q71) Explain the difference between an internal and an external sort, the pros and cons, internal sort syntax etc.
A71) An external sort is not COBOL; it is performed through JCL and PGM=SORT. It is understandable without any code reference. An internal sort can use two different syntax’s: 1.) USING, GIVING sorts are comparable to external sorts with no extra file processing; 2) INPUT PROCEDURE, OUTPUT PROCEDURE sorts allow for data manipulation before and/or after the sort.
Q72) What is the difference between comp and comp-3 usage? Explain other COBOL usage’s.
A72) Comp is a binary usage, while comp-3 indicates packed decimal. The other common usage’s are binary and display. Display is the default.
Q73) When is a scope terminator mandatory?
A73) Scope terminators are mandatory for in-line PERFORMS and EVALUATE statements. For readability, it's recommended coding practice to always make scope terminators explicit.
Q74) In a COBOL II PERFORM statement, when is the conditional tested, before or after the perform execution?
A74) In COBOL II the optional clause WITH TEST BEFORE or WITH TEST AFTER can be added to all perform statements. By default the test is performed before the perform.
Q75) In an EVALUTE statement is the order of the WHEN clauses significant?
A75) Absolutely. Evaluation of the WHEN clauses proceeds from top to bottom and their sequence can determine results.
Q76) What is the default value(s) for an INITIALIZE and what keyword allows for an override of the default.
A76) INITIALIZE moves spaces to alphabetic fields and zeros to alphanumeric fields. The REPLACING option can be used to override these defaults.
Q77) What is SET TO TRUE all about, anyway?
A77) In COBOL II the 88 levels can be set rather than moving their associated values to the related data item. (Web note: This change is not one of COBOL II's better specifications.)
Q78) What is LENGTH in COBOL II?
A78) LENGTH acts like a special register to tell the length of a group or elementary item.
Q79) What is the difference between a binary search and a sequential search? What are the pertinent COBOL
commands?
A79) In a binary search the table element key values must be in ascending or descending sequence. The table is 'halved' to search for equal to, greater than or less than conditions until the element is found. In a sequential search the table is searched from top to bottom, so (ironically) the elements do not have to be in a specific sequence. The binary search is much faster for larger tables, while sequential works well with smaller ones. SEARCH ALL is used for binary searches; SEARCH for sequential.
Q80) What is the point of the REPLACING option of a copy statement?
A80) REPLACING allows for the same copy to be used more than once in the same code by changing the replace value.
ASP,NET
1. Describe the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe in the page loading process.
inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among otherthings.When an ASP.NET request is received (usually a file with .aspx extension), the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe.
2. What’s the difference between Response.Write() andResponse.Output.Write()?
Response.Output.Write() allows you to write formatted output.
3. What methods are fired during the page load?
Init() - when the page is instantiated
Load() - when the page is loaded into server memory
PreRender() - the brief moment before the page is displayed to the user as HTML
Unload() - when page finishes loading.
4. When during the page processing cycle is ViewState available?
After the Init() and before the Page_Load(), or OnLoad() for a control.
5. What namespace does the Web page belong in the .NET Framework class hierarchy?
System.Web.UI.Page
6. Where do you store the information about the user’s locale?
System.Web.UI.Page.Culture
7. What’s the difference between Codebehind="MyCode.aspx.cs"andSrc="MyCode.aspx.cs"?
CodeBehind is relevant to Visual Studio.NET only.
8. What’s a bubbled event?
When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button, row, etc.) is quite tedious. The controls can bubble up theireventhandlers, allowing the main DataGrid event handler to take care of its constituents.
9. Suppose you want a certain ASP.NET function executed on MouseOver for a certain button. Where do you add an event handler?
Add an OnMouseOver attribute to the button. Example:btnSubmit.Attributes.Add("onmouseover","someClientCodeHere();");
10. What data types do the RangeValidator control support?
Integer, String, and Date.
11. Explain the differences between Server-side and Client-side code?
Server-side code executes on the server. Client-side code executes in the client's browser.
12. What type of code (server or client) is found in a Code-Behind class?
The answer is server-side code since code-behind is executed on the server. However, during the code-behind's execution on the server, it can render client-side code such as JavaScript to be processed in the clients browser. But just to be clear, code-behind executes on the server, thus making it server-side code.
13. Should user input data validation occur server-side or client-side? Why?
All user input data validation should occur on the server at a minimum. Additionally, client-side validation can be performed where deemed appropriate and feasable to provide a richer, more responsive experience for the user.
14. What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?
Server.Transfer transfers page processing from one page directly to the next page without making a round-trip back to the client's browser. This provides a faster response with a little less overhead on the server. Server.Transfer does not update the clients urlhistory list or current url. Response.Redirect is used to redirect the user's browser to another page or site. This performas a trip back to the client where the client's browser is redirected to the new page. The user's browser history list is updated to reflect the new address.
15. Can you explain the difference between an ADO.NET Dataset and an ADORecordset?
Valid answers are:
• A DataSet can represent an entire relational database in memory, complete with tables, relations, and views.
• A DataSet is designed to work without any continuing connection to the original data source.
• Data in a DataSet is bulk-loaded, rather than being loaded on demand.
• There's no concept of cursor types in a DataSet.
• DataSets have no current record pointer You can use For Each loops to move through the data.
• You can store many edits in a DataSet, and write them to the original data source in a single operation.
• Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.
16. What is the Global.asax used for?
The Global.asax (including the Global.asax.cs file) is used to implement application and session level events.
17. What are the Application_Start and Session_Start subroutines used for?
This is where you can set the specific variables for the Application and Session objects.
18. Can you explain what inheritance is and an example of when you might use it?
When you want to inherit (use the functionality of) another class. Example: With a base class named Employee, a Manager class could be derived from the Employee base class.
19. Whats an assembly?
Assemblies are the building blocks of the .NET framework. Overview of assemblies from MSDN
20. Describe the difference between inline and code behind.
Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.
21. Explain what a diffgram is, and a good use for one?
The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service.
22. Whats MSIL, and why should my developers need an appreciation of it if at all?
MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL. MSIL also allows the .NET Framework to JIT compile the assembly on the installed computer.
23. Which method do you invoke on the DataAdapter control to load your generated dataset with data?
The Fill() method.
24. Can you edit data in the Repeater control?
No, it just reads the information from its data source.
25. Which template must you provide, in order to display data in a Repeater control?
ItemTemplate.
26. How can you provide an alternating color scheme in a Repeater control?
Use the AlternatingItemTemplate.
27. What property must you set, and what method must you call in your code, in order to bind the data from a data source to the Repeater control?
You must set the DataSource property and call the DataBind method.
28. What base class do all Web Forms inherit from?
The Page class.
29. Name two properties common in every validation control?
ControlToValidate property and Text property.
30. Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box?
DataTextField property.
31. Which control would you use if you needed to make sure the values in two different controls matched?
CompareValidator control.
32. How many classes can a single .NET DLL contain?
It can contain many classes.
Web Service Questions
1. What is the transport protocol you use to call a Web service?
SOAP (Simple Object Access Protocol) is the preferred protocol.
2. True or False: A Web service can only be written in .NET?
False
3. What does WSDL stand for?
Web Services Description Language.
4. Where on the Internet would you look for Web services?
http://www.uddi.org
5. True or False: To test a Web service you must create a Windows application or Web application to consume this service?
False, the web service comes with a test page and it provides HTTP-GET method to test.
State Management Questions
1. What is ViewState?
ViewState allows the state of objects (serializable) to be stored in a hidden field on the page. ViewState is transported to the client and back to the server, and is not stored on the server or any other external source. ViewState is used the retain the state of server-side objects between postabacks.
2. What is the lifespan for items stored in ViewState?
Item stored in ViewState exist for the life of the current page. This includes postbacks(to the same page).
3. What does the "EnableViewState" property do? Why would I want it on or off?
It allows the page to save the users input on a form across postbacks. It saves the server-side values for a given control into ViewState, which is stored as a hidden value on the page before sending the page to the clients browser. When the page is posted back to the server the server control is recreated with the state stored in viewstate.
4. What are the different types of Session state management options available with ASP.NET?
ASP.NET provides In-Process and Out-of-Process state management. In-Process stores the session in memory on the web server. This requires the a "sticky-server" (or no load-balancing) so that the user is always reconnected to the same web server. Out-of-Process Session state management stores data in an external data source. The external data source may be either a SQL Server or a State Server service. Out-of-Process state management requires that all objects stored in session are serializable.
JAVA
What are Encapsulation, Inheritance and Polymorphism?- Encapsulation is the mechanism that binds together code and data it manipulates and keeps both safe from outside interference and misuse. Inheritance is the process by which one object acquires the properties of another object. Polymorphism is the feature that allows one interface to be used for general class actions.
What is OOPs?- Object oriented programming organizes a program around its data, i. e. , objects and a set of well defined interfaces to that data. An object-oriented program can be characterized as data controlling access to code.
What are Class, Constructor and Primitive data types?- Class is a template for multiple objects with similar features and it is a blue print for objects. It defines a type of object according to the data the object can hold and the operations the object can perform. Constructor is a special kind of method that determines how an object is initialized when created. Primitive data types are 8 types and they are: byte, short, int, long, float, double, boolean, char.
What is an Object and how do you allocate memory to it?- Object is an instance of a class and it is a software unit that combines a structured set of data with a set of operations for inspecting and manipulating that data. When an object is created using new operator, memory is allocated to it.
What are methods and how are they defined?- Methods are functions that operate on instances of classes in which they are defined. Objects can communicate with each other using methods and can call methods in other classes. Method definition has four parts. They are name of the method, type of object or primitive type the method returns, a list of parameters and the body of the method. A method’s signature is a combination of the first three parts mentioned above.
www.prepareinterview.com
What is the use of bin and lib in JDK?- Bin contains all tools such as javac, appletviewer, awt tool, etc., whereas lib contains API and all packages.
What is casting?- Casting is used to convert the value of one type to another.
How many ways can an argument be passed to a subroutine and explain them?- An argument can be passed in two ways. They are passing by value and passing by reference. Passing by value: This method copies the value of an argument into the formal parameter of the subroutine. Passing by reference: In this method, a reference to an argument (not the value of the argument) is passed to the parameter.
What are different types of access modifiers?- public: Any thing declared as public can be accessed from anywhere. private: Any thing declared as private can’t be seen outside of its class. protected: Any thing declared as protected can be accessed by classes in the same package and subclasses in the other packages. default modifier : Can be accessed only to classes in the same package.
What is final, finalize() and finally?- final : final keyword can be used for class, method and variables. A final class cannot be subclassed and it prevents other programmers from subclassing a secure class to invoke insecure methods. A final method can’t be overridden. A final variable can’t change from its initialized value. finalize() : finalize() method is used just before an object is destroyed and can be called just prior to garbage collection. finally : finally, a key word used in exception handling, creates a block of code that will be executed after a try/catch block has completed and before the code following the try/catch block. The finally block will execute whether or not an exception is thrown. For example, if a method opens a file upon exit, then you will not want the code that closes the file to be bypassed by the exception-handling mechanism. This finally keyword is designed to address this contingency.
What is UNICODE?- Unicode is used for internal representation of characters and strings and it uses 16 bits to represent each other.
What is Garbage Collection and how to call it explicitly?- When an object is no longer referred to by any variable, java automatically reclaims memory used by that object. This is known as garbage collection. System. gc() method may be used to call it explicitly.
What is finalize() method?- finalize () method is used just before an object is destroyed and can be called just prior to garbage collection.
What are Transient and Volatile Modifiers?- Transient: The transient modifier applies to variables only and it is not stored as part of its object’s Persistent state. Transient variables are not serialized. Volatile: Volatile modifier applies to variables only and it tells the compiler that the variable modified by volatile can be changed unexpectedly by other parts of the program.
What is method overloading and method overriding?- Method overloading: When a method in a class having the same method name with different arguments is said to be method overloading. Method overriding : When a method in a class having the same method name with same arguments is said to be method overriding.
What is meant by Inheritance and what are its advantages?- Inheritance is the process of inheriting all the features from a class. The advantages of inheritance are reusability of code and accessibility of variables and methods of the super class by subclasses.
What modifiers may be used with top-level class?- public, abstract and final can be used for top-level class.
What are inner class and anonymous class?- Inner class : classes defined in other classes, including those defined in methods are called inner classes. An inner class can have any accessibility including private. Anonymous class : Anonymous class is a class defined inside a method without a name and is instantiated and declared in the same place and cannot have explicit constructors.
What is a package?- A package is a collection of classes and interfaces that provides a high-level layer of access protection and name space management.
What is a reflection package?- java. lang. reflect package has the ability to analyze itself in runtime.
Software testing
. Software Testing is more Oriented to Detecting the defects or often equated to finding bugs. Testing is a process of executing a software system to determine whether it matches its specification and executes in its intended environment under controlled conditiions. The controlled conditions should include both normal and abnormal conditions. Testing should intentionally attempt to make things go wrong to determine if things happen when they shouldn't or things don't happen when they should.
SQA: - Software QA involves the entire software development PROCESS - monitoring and improving the process, making sure that any agreed-upon standards and procedures are followed, and ensuring that problems are found and dealt with. It is oriented to 'prevention'.
Stop Testing: -
Testing is potentially endless. We can not test till all the defects are unearthed and removed -- it is simply impossible. At some point, we have to stop testing and ship the software. The question is when.
Realistically, testing is a trade-off between budget, time and quality. It is driven by profit models. The pessimistic, and unfortunately most often used approach is to stop testing whenever some, or any of the allocated resources -- time, budget, or test cases -- are exhausted. The optimistic stopping rule is to stop testing when either reliability meets the requirement, or the benefit from continuing testing cannot justify the testing cost. [Yang95] This will usually require the use of reliability models to evaluate and predict reliability of the software under test. Each evaluation requires repeated running of the following cycle: failure data gathering -- modeling -- prediction. This method does not fit well for ultra-dependable systems, however, because the real field failure data will take too long to accumulate.
For Verification & Validation (V&V)
Just as topic Verification and Validation indicated, another important purpose of testing is verification and validation (V&V). Testing can serve as metrics. It is heavily used as a tool in the V&V process. Testers can make claims based on interpretations of the testing results, which either the product works under certain situations, or it does not work. We can also compare the quality among different products under the same specification, based on results from the same test.
2. What is the purpose of software testing?
The purpose of software testing is
a. To demonstrate that the product performs each function intended;
b. To demonstrate that the internal operation of the product performs according to specification and all internal components have been adequately exercised;
c. To increase our confidence in the proper functioning of the software.
d. To show the product is free from defect.
e. All of the above.
3. Types of Levels: -
COMPATIBILITY TESTING. Testing to ensure compatibility of an application or Web site with different browsers, OSs, and hardware platforms. Compatibility testing can be performed manually or can be driven by an automated functional or regression test suite.
CONFORMANCE TESTING. Verifying implementation conformance to industry standards. Producing tests for the behavior of an implementation to be sure it provides the portability, interoperability, and/or compatibility a standard defines.
FUNCTIONAL TESTING. Validating an application or Web site conforms to its specifications and correctly performs all its required functions. This entails a series of tests which perform a feature by feature validation of behavior, using a wide range of normal and erroneous input data. This can involve testing of the product's user interface, APIs, database management, security, installation, networking, etcF testing can be performed on an automated or manual basis using black box or white box methodologies.
LOAD TESTING. Load testing is a generic term covering Performance Testing and Stress Testing.
PERFORMANCE TESTING. Performance testing can be applied to understand your application or WWW site's scalability, or to benchmark the performance in an environment of third party products such as servers and middleware for potential purchase. This sort of testing is particularly useful to identify performance bottlenecks in high use applications. Performance testing generally involves an automated test suite as this allows easy simulation of a variety of normal, peak, and exceptional load conditions.
REGRESSION TESTING. Similar in scope to a functional test, a regression test allows a consistent, repeatable validation of each new release of a product or Web site. Such testing ensures reported product defects have been corrected for each new release and that no new quality problems were introduced in the maintenance process. Though regression testing can be performed manually an automated test suite is often used to reduce the time and resources needed to perform the required testing.
SMOKE TESTING. A quick-and-dirty test that the major functions of a piece of software work without bothering with finer details. Originated in the hardware testing practice of turning on a new piece of hardware for the first time and considering it a success if it does not catch on fire.
STRESS TESTING. Testing conducted to evaluate a system or component at or beyond the limits of its specified requirements to determine the load under which it fails and how. A graceful degradation under load leading to non-catastrophic failure is the desired result. Often Stress Testing is performed using the same process as Performance Testing but employing a very high level of simulated load.
UNIT TESTING. Functional and reliability testing in an Engineering environment. Producing tests for the behavior of components of a product to ensure their correct behavior prior to system integration.
Black Box Testing
Black box testing methods focus on the functional requirements of the software. Tests sets are derived that fully exercise all functional requirements. This strategy tends to be applied during the latter part of the lifecycle.
Tests are designed to answer questions such as:
1) How is functional validity tested?
2) What classes of input make good test cases?
3) Is the system particularly sensitive to certain input values?
4) How are the boundaries of data classes isolated?
5) What data rates or volumes can the system tolerate?
6) What effect will specific combinations of data have on system operation?
Equivalence Partitioning: -
This method divides the input of a program into classes of data. Test case design is based on defining an equivalent class for a particular input. An equivalence class represents a set of valid and invalid input values.
Guidelines for equivalence partitioning -
1) If an input condition specifies a range, one valid and two invalid equivalence classes are defined.
2) If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.
3) If an input condition specifies a member of a set, one valid and one invalid equivalence class are defined.
4) If an input condition is boolean, one valid and one invalid class are defined.
Boundary Value Analysis: -
Boundary value analysis is complementary to equivalence partitioning. Rather than selecting arbitrary input values to partition the equivalence class, the test case designer chooses values at the extremes of the class. Furthermore, boundary value analysis also encourages test case designers to look at output conditions and design test cases for the extreme conditions in output.
Guidelines for boundary value analysis -
1) If an input condition specifies a range bounded by values a and b, test cases should be designed with values a and b, and values just above and just below and b.
2) If an input condition specifies a number of values, test cases should be developed that exercise the minimum and maximum numbers. Values above and below the minimum and maximum are also tested.
3) Apply the above guidelines to output conditions. For example, if the requirement specifies the production of an table as output then you want to choose input conditions that produce the largest and smallest possible table.
4) For internal data structures be certain to design test cases to exercise the data structure at its boundary. For example, if the software includes the maintenance of a personnel list, then you should ensure the software is tested with conditions where the list size is 0, 1 and maximum (if constrained).
Cause-Effect Graphs
A weakness of the two methods is that do not consider potential combinations of input/output conditions. Cause-effect graphs connect input classes (causes) to output classes (effects) yielding a directed graph.
Guidelines for cause-effect graphs -
1) Causes and effects are listed for a modules and an identifier is assigned to each.
2) A cause-effect graph is developed (special symbols are required).
3) The graph is converted to a decision table.
4) Decision table rules are converted to test cases.
We can not test quality directly, but we can test related factors to make quality visible. Quality has three sets of factors -- functionality, engineering, and adaptability. These three sets of factors can be thought of as dimensions in the software quality space. Each dimension may be broken down into its component factors and considerations at successively lower levels of detail.
Performance testing
Not all software systems have specifications on performance explicitly. But every system will have implicit performance requirements. The software should not take infinite time or infinite resource to execute. "Performance bugs" sometimes are used to refer to those design problems in software that cause the system performance to degrade.
Reliability testing
Software reliability refers to the probability of failure-free operation of a system. It is related to many aspects of software, including the testing process. Directly estimating software reliability by quantifying its related factors can be difficult. Testing is an effective sampling method to measure software reliability. Guided by the operational profile, software testing (usually black-box testing) can be used to obtain failure data, and an estimation model can be further used to analyze the data to estimate the present reliability and predict future reliability. Therefore, based on the estimation, the developers can decide whether to release the software, and the users can decide whether to adopt and use the software. Risk of using software can also be assessed based on reliability information. [Hamlet94] advocates that the primary goal of testing should be to measure the dependability of tested software.
Security testing
Software quality, reliability and security are tightly coupled. Flaws in software can be exploited by intruders to open security holes. With the development of the Internet, software security problems are becoming even more severe.
Many critical software applications and services have integrated security measures against malicious attacks. The purpose of security testing of these systems include identifying and removing software flaws that may potentially lead to security violations, and validating the effectiveness of security measures. Simulated security attacks can be performed to find vulnerabilities.
TESTING means "quality control"
* QUALITY CONTROL measures the quality of a product
* QUALITY ASSURANCE measures the quality of processes used to create a quality product.
Beta testing is typically conducted by end users of a software product who are not paid a salary for their efforts.
Acceptance Testing
Testing the system with the intent of confirming readiness of the product and customer acceptance.
Ad Hoc Testing
Testing without a formal test plan or outside of a test plan. With some projects this type of testing is carried out as an adjunct to formal testing. If carried out by a skilled tester, it can often find problems that are not caught in regular testing. Sometimes, if testing occurs very late in the development cycle, this will be the only kind of testing that can be performed. Sometimes ad hoc testing is referred to as exploratory testing.
Alpha Testing
Testing after code is mostly complete or contains most of the functionality and prior to users being involved. Sometimes a select group of users are involved. More often this testing will be performed in-house or by an outside testing firm in close cooperation with the software engineering department.
Automated Testing
Software testing that utilizes a variety of tools to automate the testing process and when the importance of having a person manually testing is diminished. Automated testing still requires a skilled quality assurance professional with knowledge of the automation tool and the software being tested to set up the tests.
Beta Testing
Testing after the product is code complete. Betas are often widely distributed or even distributed to the public at large in hopes that they will buy the final product when it is released.
Black Box Testing
Testing software without any knowledge of the inner workings, structure or language of the module being tested. Black box tests, as most other kinds of tests, must be written from a definitive source document, such as a specification or requirements document..
Compatibility Testing
Testing used to determine whether other system software components such as browsers, utilities, and competing software will conflict with the software being tested.
Configuration Testing
Testing to determine how well the product works with a broad range of hardware/peripheral equipment configurations as well as on different operating systems and software.
Functional Testing
Testing two or more modules together with the intent of finding defects, demonstrating that defects are not present, verifying that the module performs its intended functions as stated in the specification and establishing confidence that a program does what it is supposed to do.
Independent Verification and Validation (IV&V)
The process of exercising software with the intent of ensuring that the software system meets its requirements and user expectations and doesn't fail in an unacceptable manner. The individual or group doing this work is not part of the group or organization that developed the software. A term often applied to government work or where the government regulates the products, as in medical devices.
Installation Testing
Testing with the intent of determining if the product will install on a variety of platforms and how easily it installs.
Integration Testing
Testing two or more modules or functions together with the intent of finding interface defects between the modules or functions. Testing completed at as a part of unit or functional testing, and sometimes, becomes its own standalone test phase. On a larger level, integration testing can involve a putting together of groups of modules and functions with the goal of completing and verifying that the system meets the system requirements. (see system testing)
Load Testing
Testing with the intent of determining how well the product handles competition for system resources. The competition may come in the form of network traffic, CPU utilization or memory allocation.
Performance Testing
Testing with the intent of determining how quickly a product handles a variety of events. Automated test tools geared specifically to test and fine-tune performance are used most often for this type of testing.
Pilot Testing
Testing that involves the users just before actual release to ensure that users become familiar with the release contents and ultimately accept it. Often is considered a Move-to-Production activity for ERP releases or a beta test for commercial products. Typically involves many users, is conducted over a short period of time and is tightly controlled. (see beta testing)
Regression Testing
Testing with the intent of determining if bug fixes have been successful and have not created any new problems. Also, this type of testing is done to ensure that no degradation of baseline functionality has occurred.
Security Testing
Testing of database and network software in order to keep company data and resources secure from mistaken/accidental users, hackers, and other malevolent attackers.
Software Testing
The process of exercising software with the intent of ensuring that the software system meets its requirements and user expectations and doesn't fail in an unacceptable manner. The organization and management of individuals or groups doing this work is not relevant. This term is often applied to commercial products such as internet applications. (contrast with independent verification and validation)
Stress Testing
Testing with the intent of determining how well a product performs when a load is placed on the system resources that nears and then exceeds capacity.
System Integration Testing
Testing a specific hardware/software installation. This is typically performed on a COTS (commerical off the shelf) system or any other system comprised of disparent parts where custom configurations and/or unique installations are the norm.
White Box Testing
Testing in which the software tester has knowledge of the inner workings, structure and language of the software, or at least its purpose.
Difference Between Verification & Validation: -
- Verification is about answering the question "Does the system function properly?" or "Have we built the system right?"
- Validation is about answering the question "Is the product what the customer wanted?" or "Have we built the right system?"
This definition indicates that Validation could be the same thing as Acceptance Test (or at least very similar).
I have often described Verification and Validation processes in the same way, ie:
1. Plan the test (output Test Plan)
2. Specify the test (output Test Specification)
3. Perform the test (output Test Log and/or Test Report
Verification & Validation
Verification typically involves reviews and meetings to evaluate documents, plans, code, requirements, and specifications. This can be done with checklists, issues lists, walkthroughs, and inspection meetings. Validation typically involves actual testing and takes place after verifications are completed. The term 'IV & V' refers to Independent Verification and Validation.
JAVA Conceptual Questions
What is the .NET Framework?
The Microsoft .NET Framework is a platform for building, deploying, and running Web Services and applications. It provides a highly productive, standards-based, multi-language environment for integrating existing investments with next-generation applications and services as well as the agility to solve the challenges of deployment and operation of Internet-scale applications. The .NET Framework consists of three main parts: the common language runtime, a hierarchical set of unified class libraries, and a componentized version of Active Server Pages called ASP.NET.
Runtime Technical Questions
Terminology
What is the common language runtime (CLR)?
The common language runtime is the execution engine for .NET Framework applications.
It provides a number of services, including the following:
o Code management (loading and execution)
o Application memory isolation
o Verification of type safety
o Conversion of IL to native code
o Access to metadata (enhanced type information)
o Managing memory for managed objects
o Enforcement of code access security
o Exception handling, including cross-language exceptions
o Interoperation between managed code, COM objects, and pre-existing DLLs (unmanaged code and data)
o Automation of object layout
o Support for developer services (profiling, debugging, and so on)
What is the common type system (CTS)?
The common type system is a rich type system, built into the common language runtime, that supports the types and operations found in most programming languages. The common type system supports the complete implementation of a wide range of programming languages.
What is the Common Language Specification (CLS)?
The Common Language Specification is a set of constructs and constraints that serves as a guide for library writers and compiler writers. It allows libraries to be fully usable from any language supporting the CLS, and for those languages to integrate with each other. The Common Language Specification is a subset of the common type system. The Common Language Specification is also important to application developers who are writing code that will be used by other developers. When developers design publicly accessible APIs following the rules of the CLS, those APIs are easily used from all other programming languages that target the common language runtime.
What is the Microsoft Intermediate Language (MSIL)?
MSIL is the CPU-independent instruction set into which .NET Framework programs are compiled. It contains instructions for loading, storing, initializing, and calling methods on objects.
Combined with metadata and the common type system, MSIL allows for true cross-language integration.
Prior to execution, MSIL is converted to machine code. It is not interpreted.
What is managed code and managed data?
Managed code is code that is written to target the services of the common language runtime (see What is the Common Language Runtime?). In order to target these services, the code must provide a minimum level of information (metadata) to the runtime. All C#, Visual Basic .NET, and JScript .NET code is managed by default. Visual Studio .NET C++ code is not managed by default, but the compiler can produce managed code by specifying a command-line switch (/CLR).
Closely related to managed code is managed data—data that is allocated and de-allocated by the common language runtime's garbage collector. C#, Visual Basic, and JScript .NET data is managed by default. C# data can, however, be marked as unmanaged through the use of special keywords. Visual Studio .NET C++ data is unmanaged by default (even when using the /CLR switch), but when using Managed Extensions for C++, a class can be marked as managed by using the __gc keyword. As the name suggests, this means that the memory for instances of the class is managed by the garbage collector. In addition, the class becomes a full participating member of the .NET Framework community, with the benefits and restrictions that brings. An example of a benefit is proper interoperability with classes written in other languages (for example, a managed C++ class can inherit from a Visual Basic class). An example of a restriction is that a managed class can only inherit from one base class.
Assemblies
What is an assembly?
An assembly is the primary building block of a .NET Framework application. It is a collection of functionality that is built, versioned, and deployed as a single implementation unit (as one or more files). All managed types and resources are marked either as accessible only within their implementation unit, or as accessible by code outside that unit.
Assemblies are self-describing by means of their manifest, which is an integral part of every assembly. The manifest:
o Establishes the assembly identity (in the form of a text name), version, culture, and digital signature (if the assembly is to be shared across applications).
o Defines what files (by name and file hash) make up the assembly implementation.
o Specifies the types and resources that make up the assembly, including which are exported from the assembly.
o Itemizes the compile-time dependencies on other assemblies.
o Specifies the set of permissions required for the assembly to run properly.
This information is used at run time to resolve references, enforce version binding policy, and validate the integrity of loaded assemblies. The runtime can determine and locate the assembly for any running object, since every type is loaded in the context of an assembly. Assemblies are also the unit at which code access security permissions are applied. The identity evidence for each assembly is considered separately when determining what permissions to grant the code it contains.
The self-describing nature of assemblies also helps makes zero-impact install and XCOPY deployment feasible.
What are private assemblies and shared assemblies?
A private assembly is used only by a single application, and is stored in that application's install directory (or a subdirectory therein). A shared assembly is one that can be referenced by more than one application. In order to share an assembly, the assembly must be explicitly built for this purpose by giving it a cryptographically strong name (referred to as a strong name). By contrast, a private assembly name need only be unique within the application that uses it.
By making a distinction between private and shared assemblies, we introduce the notion of sharing as an explicit decision. Simply by deploying private assemblies to an application directory, you can guarantee that that application will run only with the bits it was built and deployed with. References to private assemblies will only be resolved locally to the private application directory.
There are several reasons you may elect to build and use shared assemblies, such as the ability to express version policy. The fact that shared assemblies have a cryptographically strong name means that only the author of the assembly has the key to produce a new version of that assembly. Thus, if you make a policy statement that says you want to accept a new version of an assembly, you can have some confidence that version updates will be controlled and verified by the author. Otherwise, you don't have to accept them.
For locally installed applications, a shared assembly is typically explicitly installed into the global assembly cache (a local cache of assemblies maintained by the .NET Framework). Key to the version management features of the .NET Framework is that downloaded code does not affect the execution of locally installed applications. Downloaded code is put in a special download cache and is not globally available on the machine even if some of the downloaded components are built as shared assemblies.
The classes that ship with the .NET Framework are all built as shared assemblies.
If I want to build a shared assembly, does that require the overhead of signing and managing key pairs?
Building a shared assembly does involve working with cryptographic keys. Only the public key is strictly needed when the assembly is being built. Compilers targeting the .NET Framework provide command line options (or use custom attributes) for supplying the public key when building the assembly. It is common to keep a copy of a common public key in a source database and point build scripts to this key. Before the assembly is shipped, the assembly must be fully signed with the corresponding private key. This is done using an SDK tool called SN.exe (Strong Name).
Strong name signing does not involve certificates like Authenticode does. There are no third party organizations involved, no fees to pay, and no certificate chains. In addition, the overhead for verifying a strong name is much less than it is for Authenticode. However, strong names do not make any statements about trusting a particular publisher. Strong names allow you to ensure that the contents of a given assembly haven't been tampered with, and that the assembly loaded on your behalf at run time comes from the same publisher as the one you developed against. But it makes no statement about whether you can trust the identity of that publisher.
What is the difference between a namespace and an assembly name?
A namespace is a logical naming scheme for types in which a simple type name, such as MyType, is preceded with a dot-separated hierarchical name. Such a naming scheme is completely under the control of the developer. For example, types MyCompany.FileAccess.A and MyCompany.FileAccess.B might be logically expected to have functionality related to file access. The .NET Framework uses a hierarchical naming scheme for grouping types into logical categories of related functionality, such as the Microsoft® ASP.NET application framework, or remoting functionality. Design tools can make use of namespaces to make it easier for developers to browse and reference types in their code. The concept of a namespace is not related to that of an assembly. A single assembly may contain types whose hierarchical names have different namespace roots, and a logical namespace root may span multiple assemblies. In the .NET Framework, a namespace is a logical design-time naming convenience, whereas an assembly establishes the name scope for types at run time.
Application Deployment and Isolation
What options are available to deploy my .NET applications?
The .NET Framework simplifies deployment by making zero-impact install and XCOPY deployment of applications feasible. Because all requests are resolved first to the private application directory, simply copying an application's directory files to disk is all that is needed to run the application. No registration is required.
This scenario is particularly compelling for Web applications, Web Services, and self-contained desktop applications. However, there are scenarios where XCOPY is not sufficient as a distribution mechanism. An example is when the application has little private code and relies on the availability of shared assemblies, or when the application is not locally installed (but rather downloaded on demand). For these cases, the .NET Framework provides extensive code download services and integration with the Windows Installer. The code download support provided by the .NET Framework offers several advantages over current platforms, including incremental download, code access security (no more Authenticode dialogs), and application isolation (code downloaded on behalf of one application doesn't affect other applications). The Windows Installer is another powerful deployment mechanism available to .NET applications. All of the features of Windows Installer, including publishing, advertisement, and application repair will be available to .NET applications in Windows Installer 2.0.
I've written an assembly that I want to use in more than one application. Where do I deploy it?
Assemblies that are to be used by multiple applications (for example, shared assemblies) are deployed to the global assembly cache. In the prerelease and Beta builds, use the /i option to the GACUtil SDK tool to install an assembly into the cache:
gacutil /i myDll.dll
Windows Installer 2.0, which ships with Windows XP and Visual Studio .NET will be able to install assemblies into the global assembly cache.
How can I see what assemblies are installed in the global assembly cache?
The .NET Framework ships with a Windows shell extension for viewing the assembly cache. Navigating to %windir%\assembly with the Windows Explorer activates the viewer.
What is an application domain?
An application domain (often AppDomain) is a virtual process that serves to isolate an application. All objects created within the same application scope (in other words, anywhere along the sequence of object activations beginning with the application entry point) are created within the same application domain. Multiple application domains can exist in a single operating system process, making them a lightweight means of application isolation.
An OS process provides isolation by having a distinct memory address space. While this is effective, it is also expensive, and does not scale to the numbers required for large web servers. The Common Language Runtime, on the other hand, enforces application isolation by managing the memory use of code running within the application domain. This ensures that it does not access memory outside the boundaries of the domain. It is important to note that only type-safe code can be managed in this way (the runtime cannot guarantee isolation when unsafe code is loaded in an application domain).
Garbage Collection
What is garbage collection?
Garbage collection is a mechanism that allows the computer to detect when an object can no longer be accessed. It then automatically releases the memory used by that object (as well as calling a clean-up routine, called a "finalizer," which is written by the user). Some garbage collectors, like the one used by .NET, compact memory and therefore decrease your program's working set.
How does non-deterministic garbage collection affect my code?
For most programmers, having a garbage collector (and using garbage collected objects) means that you never have to worry about deallocating memory, or reference counting objects, even if you use sophisticated data structures. It does require some changes in coding style, however, if you typically deallocate system resources (file handles, locks, and so forth) in the same block of code that releases the memory for an object. With a garbage collected object you should provide a method that releases the system resources deterministically (that is, under your program control) and let the garbage collector release the memory when it compacts the working set.
Can I avoid using the garbage collected heap?
All languages that target the runtime allow you to allocate class objects from the garbage-collected heap. This brings benefits in terms of fast allocation, and avoids the need for programmers to work out when they should explicitly 'free' each object.
The CLR also provides what are called ValueTypes—these are like classes, except that ValueType objects are allocated on the runtime stack (rather than the heap), and therefore reclaimed automatically when your code exits the procedure in which they are defined. This is how "structs" in C# operate.
Managed Extensions to C++ lets you choose where class objects are allocated. If declared as managed Classes, with the __gc keyword, then they are allocated from the garbage-collected heap. If they don't include the __gc keyword, they behave like regular C++ objects, allocated from the C++ heap, and freed explicitly with the "free" method.
For additional information about Garbage Collection see:
o Garbage Collection: Automatic Memory Management in the Microsoft .NET Framework
o Garbage Collection, Part 2: Automatic Memory Management in the Microsoft .NET Framework
Remoting
How do in-process and cross-process communication work in the Common Language Runtime?
There are two aspects to in-process communication: between contexts within a single application domain, or across application domains. Between contexts in the same application domain, proxies are used as an interception mechanism. No marshaling/serialization is involved. When crossing application domains, we do marshaling/serialization using the runtime binary protocol.
Cross-process communication uses a pluggable channel and formatter protocol, each suited to a specific purpose.
o If the developer specifies an endpoint using the tool soapsuds.exe to generate a metadata proxy, HTTP channel with SOAP formatter is the default.
o If a developer is doing explicit remoting in the managed world, it is necessary to be explicit about what channel and formatter to use. This may be expressed administratively, through configuration files, or with API calls to load specific channels. Options are:
HTTP channel w/ SOAP formatter (HTTP works well on the Internet, or anytime traffic must travel through firewalls)
TCP channel w/ binary formatter (TCP is a higher performance option for local-area networks (LANs))
When making transitions between managed and unmanaged code, the COM infrastructure (specifically, DCOM) is used for remoting. In interim releases of the CLR, this applies also to serviced components (components that use COM+ services). Upon final release, it should be possible to configure any remotablecomponent.
Distributed garbage collection of objects is managed by a system called "leased based lifetime." Each object has a lease time, and when that time expires, the object is disconnected from the remoting infrastructure of the CLR. Objects have a default renew time-the lease is renewed when a successful call is made from the client to the object. The client can also explicitly renew the lease.
Interoperability
Can I use COM objects from a .NET Framework program?
Yes. Any COM component you have deployed today can be used from managed code, and in common cases the adaptation is totally automatic.
Specifically, COM components are accessed from the .NET Framework by use of a runtime callable wrapper (RCW). This wrapper turns the COM interfaces exposed by the COM component into .NET Framework-compatible interfaces. For OLE automation interfaces, the RCW can be generated automatically from a type library. For non-OLE automation interfaces, a developer may write a custom RCW and manually map the types exposed by the COM interface to .NET Framework-compatible types.
Can .NET Framework components be used from a COM program?
Yes. Managed types you build today can be made accessible from COM, and in the common case the configuration is totally automatic. There are certain new features of the managed development environment that are not accessible from COM. For example, static methods and parameterized constructors cannot be used from COM. In general, it is a good idea to decide in advance who the intended user of a given type will be. If the type is to be used from COM, you may be restricted to using those features that are COM accessible.
Depending on the language used to write the managed type, it may or may not be visible by default.
Specifically, .NET Framework components are accessed from COM by using a COM callable wrapper (CCW). This is similar to an RCW (see previous question), but works in the opposite direction. Again, if the .NET Framework development tools cannot automatically generate the wrapper, or if the automatic behavior is not what you want, a custom CCW can be developed.
Can I use the Win32 API from a .NET Framework program?
Yes. Using platform invoke, .NET Framework programs can access native code libraries by means of static DLL entry points.
Here is an example of C# calling the Win32 MessageBox function:
using System;
using System.Runtime.InteropServices;
class MainApp
{
[DllImport("user32.dll", EntryPoint="MessageBox")]
public static extern int MessageBox(int hWnd, String strMessage, String strCaption,uint uiType);
public static void Main()
{
MessageBox( 0, "Hello, this is PInvoke in operation!", ".NET", 0 );
}
}
Security
What do I have to do to make my code work with the security system?
Usually, not a thing—most applications will run safely and will not be exploitable by malicious attacks. By simply using the standard class libraries to access resources (like files) or perform protected operations (such as a reflection on private members of a type), security will be enforced by these libraries. The one simple thing application developers may want to do is include a permission request (a form of declarative security) to limit the permissions their code may receive (to only those it requires). This also ensures that if the code is allowed to run, it will do so with all the permissions it needs.
Only developers writing new base class libraries that expose new kinds of resources need to work directly with the security system. Instead of all code being a potential security risk, code access security constrains this to a very small bit of code that explicitly overrides the security system.
Why does my code get a security exception when I run it from a network shared drive?
Default security policy gives only a restricted set of permissions to code that comes from the local intranet zone. This zone is defined by the Internet Explorer security settings, and should be configured to match the local network within an enterprise. Since files named by UNC or by a mapped drive (such as with the NET USE command) are being sent over this local network, they too are in the local intranet zone.
The default is set for the worst case of an unsecured intranet. If your intranet is more secure you can modify security policy (with the .NET Framework Configuration tool or the CASPol tool) to grant more permissions to the local intranet, or to portions of it (such as specific machine share names).
How do I make it so that code runs when the security system is stopping it?
Security exceptions occur when code attempts to perform actions for which it has not been granted permission. Permissions are granted based on what is known about code; especially its location. For example, code run from the Internet is given fewer permissions than that run from the local machine because experience has proven that it is generally less reliable. So, to allow code to run that is failing due to security exceptions, you must increase the permissions granted to it. One simple way to do so is to move the code to a more trusted location (such as the local file system). But this won't work in all cases (web applications are a good example, and intranet applications on a corporate network are another). So, instead of changing the code's location, you can also change security policy to grant more permissions to that location. This is done using either the .NET Framework Configuration tool or the code access security policy utility (caspol.exe). If you are the code's developer or publisher, you may also digitally sign it and then modify security policy to grant more permissions to code bearing that signature. When taking any of these actions, however, remember that code is given fewer permissions because it is not from an identifiably trustworthy source—before you move code to your local machine or change security policy, you should be sure that you trust the code to not perform malicious or damaging actions.
How do I administer security for my machine? For an enterprise?
The .NET Framework includes the .NET Framework Configuration tool, an MMC snap-in (mscorcfg.msc), to configure several aspects of the CLR including security policy. The snap-in not only supports administering security policy on the local machine, but also creates enterprise policy deployment packages compatible with System Management Server and Group Policy. A command line utility, CASPol.exe, can also be used to script policy changes on the computer. In order to run either tool, in a command prompt, change the current directory to the installation directory of the .NET Framework (located in %windir%\Microsoft.Net\Framework\v1.0.2914.16\) and type mscorcfg.msc or caspol.exe.
How does evidence-based security work with Windows 2000 security?
Evidence-based security (which authorizes code) works together with Windows 2000 security (which is based on log on identity). For example, to access a file, managed code must have both the code access security file permission and must also be running under a log on identity that has NTFS file access rights. The managed libraries that are included with the .NET Framework also provide classes for role-based security. These allow the application to work with Windows log on identities and user groups.
What is interface and its use?- Interface is similar to a class which may contain method’s signature only but not bodies and it is a formal set of method and constant declarations that must be defined by the class that implements it. Interfaces are useful for: a)Declaring methods that one or more classes are expected to implement b)Capturing similarities between unrelated classes without forcing a class relationship. c)Determining an object’s programming interface without revealing the actual body of the class.
What is an abstract class?- An abstract class is a class designed with implementation gaps for subclasses to fill in and is deliberately incomplete.
What is a cloneable interface and how many methods does it contain?- It is not having any method because it is a TAGGED or MARKER interface.
Can you have an inner class inside a method and what variables can you access?- Yes, we can have an inner class inside a method and final variables can be accessed.
What is multithreading and what are the methods for inter-thread communication and what is the class in which these methods are defined?- Multithreading is the mechanism in which more than one thread run independent of each other within the process. wait (), notify () and notifyAll() methods can be used for inter-thread communication and these methods are in Object class. wait() : When a thread executes a call to wait() method, it surrenders the object lock and enters into a waiting state. notify() or notifyAll() : To remove a thread from the waiting state, some other thread must make a call to notify() or notifyAll() method on the same object.
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What is the class and interface in java to create thread and which is the most advantageous method?- Thread class and Runnable interface can be used to create threads and using Runnable interface is the most advantageous method to create threads because we need not extend thread class here.
What are the states associated in the thread?- Thread contains ready, running, waiting and dead states.
What is synchronization?- Synchronization is the mechanism that ensures that only one thread is accessed the resources at a time.
When you will synchronize a piece of your code?- When you expect your code will be accessed by different threads and these threads may change a particular data causing data corruption.
What is deadlock?- When two threads are waiting each other and can’t precede the program is said to be deadlock.
What is daemon thread and which method is used to create the daemon thread?- Daemon thread is a low priority thread which runs intermittently in the back ground doing the garbage collection operation for the java runtime system. setDaemon method is used to create a daemon thread.
Are there any global variables in Java, which can be accessed by other part of your program?-No, it is not the main method in which you define variables. Global variables is not possible because concept of encapsulation is eliminated here.
What is an applet?- Applet is a dynamic and interactive program that runs inside a web page displayed by a java capable browser.
How does applet recognize the height and width?- Using getParameters() method.
When do you use codebase in applet?- When the applet class file is not in the same directory, codebase is used.
What is the lifecycle of an applet?- init() method - Can be called when an applet is first loaded start() method - Can be called each time an applet is started. paint() method - Can be called when the applet is minimized or maximized. stop() method - Can be used when the browser moves off the applet’s page. destroy() method - Can be called when the browser is finished with the applet.
How do you set security in applets?- using setSecurityManager() method
What is an event and what are the models available for event handling?- An event is an event object that describes a state of change in a source. In other words, event occurs when an action is generated, like pressing button, clicking mouse, selecting a list, etc. There are two types of models for handling events and they are: a) event-inheritance model and b) event-delegation model
What are the advantages of the model over the event-inheritance model?- The event-delegation model has two advantages over the event-inheritance model. They are: a)It enables event handling by objects other than the ones that generate the events. This allows a clean separation between a component’s design and its use. b)It performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to be repeatedly process unhandled events as is the case of the event-inheritance.
What is source and listener?- source : A source is an object that generates an event. This occurs when the internal state of that object changes in some way. listener : A listener is an object that is notified when an event occurs. It has two major requirements. First, it must have been registered with one or more sources to receive notifications about specific types of events. Second, it must implement methods to receive and process these notifications.
What is adapter class?- An adapter class provides an empty implementation of all methods in an event listener interface. Adapter classes are useful when you want to receive and process only some of the events that are handled by a particular event listener interface. You can define a new class to act listener by extending one of the adapter classes and implementing only those events in which you are interested. For example, the MouseMotionAdapter class has two methods, mouseDragged()and mouseMoved(). The signatures of these empty are exactly as defined in the MouseMotionListener interface. If you are interested in only mouse drag events, then you could simply extend MouseMotionAdapter and implement mouseDragged() .
What is meant by controls and what are different types of controls in AWT?- Controls are components that allow a user to interact with your application and the AWT supports the following types of controls: Labels, Push Buttons, Check Boxes, Choice Lists, Lists, Scrollbars, Text Components. These controls are subclasses of Component.
What is a layout manager and what are different types of layout managers available in java AWT?- A layout manager is an object that is used to organize components in a container. The different layouts are available are FlowLayout, BorderLayout, CardLayout, GridLayout and GridBagLayout.
How are the elements of different layouts organized?- FlowLayout: The elements of a FlowLayout are organized in a top to bottom, left to right fashion. BorderLayout: The elements of a BorderLayout are organized at the borders (North, South, East and West) and the center of a container. CardLayout: The elements of a CardLayout are stacked, on top of the other, like a deck of cards. GridLayout: The elements of a GridLayout are of equal size and are laid out using the square of a grid. GridBagLayout: The elements of a GridBagLayout are organized according to a grid. However, the elements are of different size and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes.
Which containers use a Border layout as their default layout?- Window, Frame and Dialog classes use a BorderLayout as their layout.
GENERAL APTITUDE
A man starts his walking at 3PM from point A, he walks at the rate of 4km/hr in plains and 3km/hr in hills to reach the point B. During his return journey he walks at the rate of 6km/hr in hills and 4km/hr in plains and reaches the point A at 9PM.What is the distance between A and B?
Ans: 12km
Solution:
T1+T2=6
T1-time for forward journey,
T2-time for return journey
D1+D2=forward /return distance
D1-distance in plains
D2-distance in hills
D1/4 +D2/3=T1 (forward time)
D1/4 +D2/6=T2 (return time)
Adding we will get D1+D2=12 km
2. A boy asks his father, " what is the age of grand father?". Father replied " He is x years old in x^2 years", and also said, "we are talking about 20th century". what is the year of birth of grand father?
Ans: 1892
3. A boy travels in a scooter after covering 2/3rd of the distance the wheel got punctured he covered the remaining distance by walk. Walking time is twice that of the time the boy’s riding time. How many times the riding speed as that of the walking speed?
Ans: 4 times.
4. In a Knockout tournament 51 teams are participated, every team thrown out of the tournament if they lost twice. How many matches to be held to choose the winner?
Ans: 101 matches
5. A man sold 2 pens. Initial cost of each pen was Rs. 12. If he sell it together one at 25% profit and another 20% loss. Find the amount of loss or gain, if he sells them separately.
Ans: 60 Paise gain
6. Find the 3 digit no. whose last digit is the square root of the first digit and second digit is the sum of the other two digits.
Ans: 462
7. Meera was playing with her brother using 55 blocks. She gets bored playing and starts arranging the blocks such that the no. of blocks in each row is one less than that in the lower row. Find how many were there in the bottom most row?
Ans: 10
8. Two people are playing with a pair of dies. Instead of numbers, the dies have different colors on their sides. The first person wins if the same color appears on both the dies and the second person wins if the colors are different. The odds of their winning are equal. If the first dice has 5 red sides and 1 blue side, find the color(s) on the second one.
Ans: 3 Red, 3 Blue
9. A person travels in a car with uniform speed. He observes the milestone, which has 2 digits. After one hour he observes another milestone with same digits reversed. After another hour he observes another milestone with same 2 digits separated by 0. Find the speed of the car?
Ans : 45
10. Three persons A, B &C went for a robbery in different directions and they theft one horse, one mule and one camel. They were caught by the police and when interrogated gave the following statements
A: B has stolen the horse
B: I didn't rob anything.
C: both A & B are false and B has stolen the mule.
The person who has stolen the horse always tell the truth and
The person who has stolen the camel always tell the lie.
Find who has stolen which animal?
Ans:
A- camel
B- mule
C- horse
11. One quarter of the time till now from midnight and half of the time remaining from now up to midnightadds to the present time. What is the present time?
Ans: 9:36AM
12. After world war II three departments did as follows First department gave some tanks to 2nd &3rd departments equal to the number they are having. Then 2nd department gave some tanks to 1st & 3rd departments equal to the number they are having. Then 3rd department gave some tanks to 2nd &1st departments equal to the number they are having. Then each department has 24 tanks. Find the initial number of tanks of each department?
Ans :
A-39
B-21
C-12
13. A, B, C, D&E are having their birthdays on consecutive days of the week not necessarily in the same order. A 's birthday comes before G's as many days as B's birthday comes after E's. D is older than E by 2 days. This time G's birthday came on Wednesday. Then find the day of each of their birthdays?
Ans:
Birthday of D on SUNDAY
Birthday of B on MONDAY
Birthday of E on TUESDAY
Birthday of G on WEDNESDAY
Birthday of A on THURSDAY
14. A girl 'A' told to her friend about the size and color of a snake she has seen in the beach. It is one of the colors brown/black/green and one of the sizes 35/45/55.
If it were not green or if it were not of length 35 it is 55.
If it were not black or if it were not of length 45 it is 55.
If it were not black or if it were not of length 35 it is 55.
a) What is the color of the snake?
b) What is the length of the snake?
Ans:
a) brown
b) 55
15. There are 2 persons each having same amount of marbles in the beginning. after that 1 person gain 20 more from second person n he eventually lose two third of it during the play n the second person now have 4 times marble of what 1st person is having now. find out how much marble did each had in the beginning.
Ans - 100 each
16. A lady was out for shopping. she spent half of her money in buying A and gave 1 dollar to bagger. fathershe spent half of her remaining money and gave 2 dollar to charity. further she spent half of remaining money n gave 3 dollar to some children. now she has left with 1 dollar. how much she had in the beginning?
Ans: $42
17. There are certain diamonds in a shop.
1 thief stole half of diamonds and 2 more.
2 thief stole half of remaining and 2 more
3. same as above
4 same as above.
5 came nothing was left for that.
how many diamonds was there???
Ans: 60 diamonds
18. There are three friends A B C.
1. Either A or B is oldest
2. Either C is oldest or A is youngest.
Who is Youngest and who is Oldest?
Ans: A is youngest n B is oldest.
19. Father says my son is five times older than my daughter. my wife is 5 times older that my son. I am twice old from my wife and altogether (sum of our ages) is equal to my mother 's age and she is celebrating her 81 birthday. so what is my son's age?
Ans: 5 years.
20. Fodder, Wheat and Rice often eat dinner out.
a) each orders either coffee or tea after dinner.
b) if fodder orders coffee, then Wheat orders the drink that Rice orders
c) if Wheat orders coffee, then fodder orders the drink that Rice does not order
d) if Rice orders tea, then fodder orders the drink that Wheat orders
which person/persons always orders the same drink after dinner ?
Ans: Fodder
21. We are given 100 pieces of a puzzle. If fixing two components together is counted as 1 move ( acomponent can be one piece or an already fixed set of pieces), how many moves do we need to fix the entire puzzle.
Ans: 99
22. Two guys work at some speed...After some time one guy realizes he has done only half of the other guy completed which is equal to half of what is left !
So how much faster than the other is this guy supposed to do to finish with the first...
Ans: one and half times or 3/2
23. There is a square cabbage patch. He told his sister that i have a larger patch than last year and hence 211 more cabbages this year. Then how many cabbages I have this year.?
Ans:106*106=11236
24. There are three guesses on the color of a mule
1 says: its not black
2 says: its brown or grey
3 says: its brown
At least one of them is wrong and one of them is true.....Then what’s the color of mule?
Ans: Grey
25. There are two containers on a table. A and B . A is half full of wine, while B, which is twice A's size, is one quarter full of wine . Both containers are filled with water and the contents are poured into a third container C. What portion of container C's mixture is wine ?
Ans:33.33%
26. A man was on his way to a marriage in a car with a constant speed. After 2 hours one of the tier is punctured and it took 10 minutes to replace it. After that they traveled with a speed of 30 miles/hr and reached the marriage 30 minutes late to the scheduled time. The driver told that they would be late by 15 minutes only if the 10 minutes was not waste. Find the distance between the two towns?
Ans: 120 miles
27. Farmer Jones sold a pair of cows for Rs. 210 , On one he made a profit of ten percent and on the other he lost ten percent. Although he made a profit of five percent. How many did each cow originally cost him?
Ans:150,50
28. I spent one-sixth of my age as a boy and one-12th in youth, remarked the boss "spent one-seventh and five years in matrimony". My son born just after that period was elected as a governor 4 years back when he was half of my present age. What is the age of the boss?
Ans: 84
29. A girl had several dollars with her. she went out for shopping and spent half of them in shopping mall, being generous she had given 1 dollar to the beggar. After that she went for lunch and spent the half of the remaining and gave 2 dollars as tip to the waiter. Then she went to watch a movie and spent the half of remaining dollars and gave autorikshaw-wala 3 dollars. This left her with only 1 dollar. How many dollars did she had with her at the beginning.
Ans:$42.
30. A bargain hunter bought some plates for $ 1.30 from a sale on Saturday, where price 2cents was marked off at each article .On Monday she went to return them at regular prices, and bought some cups and saucers from that much amount of money only. The normal price of plate were equal to the price of 'one cup and one saucer'. In total she bought 16 items more than previous. saucers were only of 3 cents hence she brought 10 saucers more than the cups, How many cups and saucers she bought and at what price?
Ans: 8,18 Price: 12,3.
31. Mr. T has a wrong weighing pan. One arm is lengthier than other.1 kilogram on left balances 8 melons on right.1 kilogram on right balances 2 melons on left. If all melons are equal in weight, what is the weight of a single melon?
Ans:200 gms
32. A card board of 34 * 14 has to be attached to a wooden box and a total of 35 pins are to be used on the each side of the cardbox. Find the total number of pins used .
Ans: 210
33. Last Year my cousin came to my place and we played a game where the loosing one has to give one chocolate to the person who won the game .At the end of the vacation, i.e. the day my cousin was leaving she counted number of games that i won an she won. At last she gave me a total of 8 chocolates even though she won about 12 games. Find the number of games that we played.
Ans: 20
34. Here is a five digit number. The fifth digit is one fourth of the third digit and one half of the fourth digit. Third digit is one half of the first digit. second digit is 5 more than the fifth digit.
What is that 5 digit no.?
Ans: 86421
35. A boy goes to school from his house. On one fourth of his way to school, he crosses a
machinery station. And on one third of his way to school, he crosses a Railway station.
He crossed the machinery station at 7:30 and he crosses the Railway station at 7:35.
when does he leave the house & when does he reach the school ? (5M)
Ans: 7:15 - 8:15
36. Four persons A,B,C,D were there. All were of different weights. All Four gave a
statement. Among the four statements only the person who is lightest in weight of all
others gave a true statement.
A Says : B is heavier than D.
B Says : A is heavier than C.
C Says : I am heavier than D.
D Says : C is heavier than B.
Ans: ACDB.
37. A man was traveling to a place 30 miles away from starting point. he was speeding at 60 miles/hr. but when he came back, his car got breakdown and half an hour was wasted in repairing that. altogether he took 1 hr for return journey. Find the avg. speed of the whole journey.
Ans:60 miles/hour.
Is it possible to communicate from an applet to servlet and how many ways and how?- Yes, there are three ways to communicate from an applet to servlet and they are: a) HTTP Communication(Text-based and object-based) b) Socket Communication c) RMI Communication
What is connection pooling?- With servlets, opening a database connection is a major bottleneck because we are creating and tearing down a new connection for every page request and the time taken to create connection will be more. Creating a connection pool is an ideal approach for a complicated servlet. With a connection pool, we can duplicate only the resources we need to duplicate rather than the entire servlet. A connection pool can also intelligently manage the size of the pool and make sure each connection remains valid. A number of connection pool packages are currently available. Some like DbConnectionBroker are freely available from Java Exchange Works by creating an object that dispenses connections and connection Ids on request. The ConnectionPool class maintains a Hastable, using Connection objects as keys and Boolean values as stored values. The Boolean value indicates whether a connection is in use or not. A program calls getConnection() method of the ConnectionPool for getting Connection object it can use; it calls returnConnection() to give the connection back to the pool.
Why should we go for interservlet communication?- Servlets running together in the same server communicate with each other in several ways. The three major reasons to use interservlet communication are: a) Direct servlet manipulation - allows to gain access to the other currently loaded servlets and perform certain tasks (through the ServletContext object) b) Servlet reuse - allows the servlet to reuse the public methods of another servlet. c) Servlet collaboration - requires to communicate with each other by sharing specific information (through method invocation)
Is it possible to call servlet with parameters in the URL?- Yes. You can call a servlet with parameters in the syntax as (?Param1 = xxx || m2 = yyy).
What is Servlet chaining?- Servlet chaining is a technique in which two or more servlets can cooperate in servicing a single request. In servlet chaining, one servlet’s output is piped to the next servlet’s input. This process continues until the last servlet is reached. Its output is then sent back to the client.
www.prepareinterview.com
How do servlets handle multiple simultaneous requests?- The server has multiple threads that are available to handle requests. When a request comes in, it is assigned to a thread, which calls a service method (for example: doGet(), doPost() and service()) of the servlet. For this reason, a single servlet object can have its service methods called by many threads at once.
What is Inet address?- Every computer connected to a network has an IP address. An IP address is a number that uniquely identifies each computer on the Net. An IP address is a 32-bit number.
What is Domain Naming Service(DNS)?- It is very difficult to remember a set of numbers(IP address) to connect to the Internet. The Domain Naming Service(DNS) is used to overcome this problem. It maps one particular IP address to a string of characters. For example, www. mascom. com implies com is the domain name reserved for US commercial sites, moscom is the name of the company and www is the name of the specific computer, which is mascom’s server.
What is URL?- URL stands for Uniform Resource Locator and it points to resource files on the Internet. URL has four components: http://www. address. com:80/index.html, where http - protocol name, address - IP address or host name, 80 - port number and index.html - file path.
What is RMI and steps involved in developing an RMI object?- Remote Method Invocation (RMI) allows java object that executes on one machine and to invoke the method of a Java object to execute on another machine. The steps involved in developing an RMI object are: a) Define the interfaces b) Implementing these interfaces c) Compile the interfaces and their implementations with the java compiler d) Compile the server implementation with RMI compiler e) Run the RMI registry f) Run the application
What is RMI architecture?- RMI architecture consists of four layers and each layer performs specific functions: a) Application layer - contains the actual object definition. b) Proxy layer - consists of stub and skeleton. c) Remote Reference layer - gets the stream of bytes from the transport layer and sends it to the proxy layer. d) Transportation layer - responsible for handling the actual machine-to-machine communication.
what is UnicastRemoteObject?- All remote objects must extend UnicastRemoteObject, which provides functionality that is needed to make objects available from remote machines.
Explain the methods, rebind() and lookup() in Naming class?- rebind() of the Naming class(found in java. rmi) is used to update the RMI registry on the server machine. Naming. rebind(”AddSever”, AddServerImpl); lookup() of the Naming class accepts one argument, the rmi URL and returns a reference to an object of type AddServerImpl.
What is a Java Bean?- A Java Bean is a software component that has been designed to be reusable in a variety of different environments.
What is a Jar file?- Jar file allows to efficiently deploying a set of classes and their associated resources. The elements in a jar file are compressed, which makes downloading a Jar file much faster than separately downloading several uncompressed files. The package java. util. zip contains classes that read and write jar files.
What is BDK?- BDK, Bean Development Kit is a tool that enables to create, configure and connect a set of set of Beans and it can be used to test Beans without writing a code.
What is JSP?- JSP is a dynamic scripting capability for web pages that allows Java as well as a few special tags to be embedded into a web file (HTML/XML, etc). The suffix traditionally ends with .jsp to indicate to the web server that the file is a JSP files. JSP is a server side technology - you can’t do any client side validation with it. The advantages are: a) The JSP assists in making the HTML more functional. Servlets on the other hand allow outputting of HTML but it is a tedious process. b) It is easy to make a change and then let the JSP capability of the web server you are using deal with compiling it into a servlet and running it.
What are JSP scripting elements?- JSP scripting elements lets to insert Java code into the servlet that will be generated from the current JSP page. There are three forms: a) Expressions of the form <%= expression %> that are evaluated and inserted into the output, b) Scriptlets of the form<% code %>that are inserted into the servlet’s service method, and c) Declarations of the form <%! Code %>that are inserted into the body of the servlet class, outside of any existing methods.
What are JSP Directives?- A JSP directive affects the overall structure of the servlet class. It usually has the following form:<%@ directive attribute=”value” %> However, you can also combine multiple attribute settings for a single directive, as follows:<%@ directive attribute1=”value1? attribute 2=”value2? . . . attributeN =”valueN” %> There are two main types of directive: page, which lets to do things like import classes, customize the servlet superclass, and the like; and include, which lets to insert a file into the servlet class at the time the JSP file is translated into a servlet
What are Predefined variables or implicit objects?- To simplify code in JSP expressions and scriptlets, we can use eight automatically defined variables, sometimes called implicit objects. They are request, response, out, session, application, config, pageContext, and page.
What are JSP ACTIONS?- JSP actions use constructs in XML syntax to control the behavior of the servlet engine. You can dynamically insert a file, reuse JavaBeans components, forward the user to another page, or generate HTML for the Java plugin. Available actions include: jsp:include - Include a file at the time the page is requested. jsp:useBean - Find or instantiate a JavaBean. jsp:setProperty - Set the property of a JavaBean. jsp:getProperty - Insert the property of a JavaBean into the output. jsp:forward - Forward the requester to a newpage. Jsp: plugin - Generate browser-specific code that makes an OBJECT or EMBED
How do you pass data (including JavaBeans) to a JSP from a servlet?- (1) Request Lifetime: Using this technique to pass beans, a request dispatcher (using either “include” or forward”) can be called. This bean will disappear after processing this request has been completed. Servlet: request. setAttribute(”theBean”, myBean); RequestDispatcher rd = getServletContext(). getRequestDispatcher(”thepage. jsp”); rd. forward(request, response); JSP PAGE:
How can I set a cookie in JSP?- response. setHeader(”Set-Cookie”, “cookie string”); To give the response-object to a bean, write a method setResponse (HttpServletResponse response) - to the bean, and in jsp-file:<% bean. setResponse (response); %>
How can I delete a cookie with JSP?- Say that I have a cookie called “foo, ” that I set a while ago & I want it to go away. I simply: <% Cookie killCookie = new Cookie(”foo”, null); KillCookie. setPath(”/”); killCookie. setMaxAge(0); response. addCookie(killCookie); %>
How are Servlets and JSP Pages related?- JSP pages are focused around HTML (or XML) with Java codes and JSP tags inside them. When a web server that has JSP support is asked for a JSP page, it checks to see if it has already compiled the page into a servlet. Thus, JSP pages become servlets and are transformed into pure Java and then compiled, loaded into the server and executed.
MAINFRAME
) Name the divisions in a COBOL program ?.
A1) IDENTIFICATION DIVISION, ENVIRONMENT DIVISION, DATA DIVISION, PROCEDURE DIVISION.
Q2) What are the different data types available in COBOL?
A2) Alpha-numeric (X), alphabetic (A) and numeric (9).
Q3) What does the INITIALIZE verb do? - GS
A3) Alphabetic, Alphanumeric fields & alphanumeric edited items are set to SPACES. Numeric, Numeric edited items set to ZERO. FILLER , OCCURS DEPENDING ON items left untouched.
Q4) What is 77 level used for ?
A4) Elementary level item. Cannot be subdivisions of other items (cannot be qualified), nor can they be subdivided themselves.
Q5) What is 88 level used for ?
A5) For condition names.
Q6) What is level 66 used for ?
A6) For RENAMES clause.
Q7) What does the IS NUMERIC clause establish ?
A7) IS NUMERIC can be used on alphanumeric items, signed numeric & packed decimal items and unsigned numeric & packed decimal items. IS NUMERIC returns TRUE if the item only consists of 0-9. However, if the item being tested is a signed item, then it may contain 0-9, + and - .
Q8) How do you define a table/array in COBOL?
A8) ARRAYS.
05 ARRAY1 PIC X(9) OCCURS 10 TIMES.
05 ARRAY2 PIC X(6) OCCURS 20 TIMES INDEXED BY WS-INDEX.
Q9) Can the OCCURS clause be at the 01 level?
A9) No.
Q10) What is the difference between index and subscript? - GS
A10) Subscript refers to the array occurrence while index is the displacement (in no of bytes) from the beginning of the
array. An index can only be modified using PERFORM, SEARCH & SET. Need to have index for a table in order to
use SEARCH, SEARCH ALL.
Q11) What is the difference between SEARCH and SEARCH ALL? - GS
A11) SEARCH - is a serial search.
SEARCH ALL - is a binary search & the table must be sorted ( ASCENDING/DESCENDING KEY clause to be used & data loaded in this order) before using SEARCH ALL.
Q12) What should be the sorting order for SEARCH ALL? - GS
A12) It can be either ASCENDING or DESCENDING. ASCENDING is default. If you want the search to be done on an
array sorted in descending order, then while defining the array, you should give DESCENDING KEY clause. (You
must load the table in the specified order).
Q13) What is binary search?
A13) Search on a sorted array. Compare the item to be searched with the item at the center. If it matches, fine else repeat the process with the left half or the right half depending on where the item lies.
Q14) My program has an array defined to have 10 items. Due to a bug, I find that even if the program access the
11th item in this array, the program does not abend. What is wrong with it?
A14) Must use compiler option SSRANGE if you want array bounds checking. Default is NOSSRANGE.
Q15) How do you sort in a COBOL program? Give sort file definition, sort statement syntax and meaning. - GS
A15) Syntax: SORT file-1 ON ASCENDING/DESCENDING KEY key.... USING file-2 GIVING file-3.
USING can be substituted by INPUT PROCEDURE IS para-1 THRU para-2
GIVING can be substituted by OUTPUT PROCEDURE IS para-1 THRU para-2.
file-1 is the sort (work) file and must be described using SD entry in FILE SECTION.
file-2 is the input file for the SORT and must be described using an FD entry in FILE SECTION and SELECT
clause in FILE CONTROL.
file-3 is the out file from the SORT and must be described using an FD entry in FILE SECTION and SELECT
clause in FILE CONTROL.
file-1, file-2 & file-3 should not be opened explicitly.
INPUT PROCEDURE is executed before the sort and records must be RELEASEd to the sort work file from the input procedure.
OUTPUT PROCEDURE is executed after all records have been sorted. Records from the sort work file must be RETURNed one at a time to the output procedure.
Q16) How do you define a sort file in JCL that runs the COBOL program?
A16) Use the SORTWK01, SORTWK02,..... dd names in the step. Number of sort datasets depends on the volume of data
being sorted, but a minimum of 3 is required.
Q17) What is the difference between performing a SECTION and a PARAGRAPH? - GS
A17) Performing a SECTION will cause all the paragraphs that are part of the section, to be performed.
Performing a PARAGRAPH will cause only that paragraph to be performed.
Q18) What is the use of EVALUATE statement? - GS
A18) Evaluate is like a case statement and can be used to replace nested Ifs. The difference between EVALUATE and
case is that no 'break' is required for EVALUATE i.e. control comes out of the EVALUATE as soon as one match is
made.
Q19) What are the different forms of EVALUATE statement?
A19)
EVALUATE EVALUATE SQLCODE ALSO FILE-STATUS
WHEN A=B AND C=D WHEN 100 ALSO '00'
imperative stmt imperative stmt
WHEN (D+X)/Y = 4 WHEN -305 ALSO '32'
imperative stmt imperative stmt
WHEN OTHER WHEN OTHER
imperative stmt imperative stmt
END-EVALUATE END-EVALUATE
EVALUATE SQLCODE ALSO A=B EVALUATE SQLCODE ALSO TRUE
WHEN 100 ALSO TRUE WHEN 100 ALSO A=B
imperative stmt imperative stmt
WHEN -305 ALSO FALSE WHEN -305 ALSO (A/C=4)
imperative stmt imperative stmt
END-EVALUATE END-EVALUATE
Q20) How do you come out of an EVALUATE statement? - GS
A20) After the execution of one of the when clauses, the control is automatically passed on to the next sentence after the
EVALUATE statement. There is no need of any extra code.
Q21) In an EVALUATE statement, can I give a complex condition on a when clause?
A21) Yes.
Q22) What is a scope terminator? Give examples.
A22) Scope terminator is used to mark the end of a verb e.g. EVALUATE, END-EVALUATE; IF, END-IF.
Q23) How do you do in-line PERFORM? - GS
A23) PERFORM ...
END-PERFORM
Q24) When would you use in-line perform?
A24) When the body of the perform will not be used in other paragraphs. If the body of the perform is a generic type of code
(used from various other places in the program), it would be better to put the code in a separate Paraand use
PERFORM Para name rather than in-line perform.
Q25) What is the difference between CONTINUE & NEXT SENTENCE ?
A25) They appear to be similar, that is, the control goes to the next sentence in the paragraph. But, Next Sentence would
take the control to the sentence after it finds a full stop (.). Check out by writing the following code example, one if
sentence followed by 3 display statements (sorry they appear one line here because of formatting restrictions) If 1 > 0
then next sentence end if display 'line 1' display 'line 2'. display 'line 3'. *** Note- there is a dot (.) only at the end of
the last 2 statements, see the effect by replacing Next Sentence with Continue ***
Q26) What does EXIT do ?
A26) Does nothing ! If used, must be the only sentence within a paragraph.
Q27) Can I redefine an X(100) field with a field of X(200)?
A27) Yes. Redefines just causes both fields to start at the same location. For example:
01 WS-TOP PIC X(1)
01 WS-TOP-RED REDEFINES WS-TOP PIC X(2).
If you MOVE '12' to WS-TOP-RED,
DISPLAY WS-TOP will show 1 while
DISPLAY WS-TOP-RED will show 12.
Q28) Can I redefine an X(200) field with a field of X(100) ?
A31) Yes.
Q31) What do you do to resolve SOC-7 error? - GS
A31) Basically you need to correcting the offending data. Many times the reason for SOC7 is an un-initialized numeric item.
Examine that possibility first. Many installations provide you a dump for run time abend’s ( it can be generated also
by calling some subroutines or OS services thru assembly language). These dumps provide the offset of the last
instruction at which the abend occurred. Examine the compilation output XREF listing to get the verb and the line
number of the source code at this offset. Then you can look at the source code to find the bug. To get capture the
runtime dumps, you will have to define some datasets (SYSABOUT etc ) in the JCL. If none of these are helpful, use
judgement and DISPLAY to localize the source of error. Some installation might have batch program debugging
tools. Use them.
Q32) How is sign stored in Packed Decimal fields and Zoned Decimal fields?
A32) Packed Decimal fields: Sign is stored as a hex value in the last nibble (4 bits ) of the storage.
Zoned Decimal fields: As a default, sign is over punched with the numeric value stored in the last bite.
Q33) How is sign stored in a comp-3 field? - GS
A33) It is stored in the last nibble. For example if your number is +100, it stores hex 0C in the last byte, hex 1C if
your number is 101, hex 2C if your number is 102, hex 1D if the number is -101, hex 2D if the number is –102 etc...
Q34) How is sign stored in a COMP field ? - GS
A34) In the most significant bit. Bit is ON if -ve, OFF if +ve.
Q35) What is the difference between COMP & COMP-3 ?
A35) COMP is a binary storage format while COMP-3 is packed decimal format.
Q36) What is COMP-1? COMP-2?
A36) COMP-1 - Single precision floating point. Uses 4 bytes.
COMP-2 - Double precision floating point. Uses 8 bytes.
Q37) How do you define a variable of COMP-1? COMP-2?
A37) No picture clause to be given. Example 01 WS-VAR USAGE COMP-1.
Q38) How many bytes does a S9(7) COMP-3 field occupy ?
A38) Will take 4 bytes. Sign is stored as hex value in the last nibble. General formula is INT((n/2) + 1)), where n=7 in this
example.
Q39) How many bytes does a S9(7) SIGN TRAILING SEPARATE field occupy ?
A39) Will occupy 8 bytes (one extra byte for sign).
Q40) How many bytes will a S9(8) COMP field occupy ?
A40) 4 bytes.
Q41) What is the maximum value that can be stored in S9(8) COMP?
A41) 99999999
Q42) What is COMP SYNC?
A42) Causes the item to be aligned on natural boundaries. Can be SYNCHRONIZED LEFT or RIGHT. For binary data
items, the address resolution is faster if they are located at word boundaries in the memory. For example, on main
frame the memory word size is 4 bytes. This means that each word will start from an address divisible by 4. If my
first variable is x(3) and next one is s9(4) comp, then if you do not specify the SYNC clause, S9(4) COMP will start
from byte 3 ( assuming that it starts from 0 ). If you specify SYNC, then the binary data item will start from address 4.
You might see some wastage of memory, but the access to this computational field is faster.
Q43) What is the maximum size of a 01 level item in COBOL I? in COBOL II?
A43) In COBOL II: 16777215
Q44) How do you reference the following file formats from COBOL programs:
A44)
Fixed Block File - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS F,
BLOCK CONTAINS 0 .
Fixed Unblocked - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS F,
do not use BLOCK CONTAINS
Variable Block File - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS V, BLOCK
CONTAINS 0. Do not code the 4 bytes for record length in FD ie JCL reclength will be max rec length in pgm + 4
Variable Unblocked - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS V, do not use
BLOCK CONTAINS. Do not code 4 bytes for record length in FD ie JCL reclength will
be max rec length in pgm + 4.
ESDS VSAM file - Use ORGANISATION IS SEQUENTIAL.
KSDS VSAM file - Use ORGANISATION IS INDEXED, RECORD KEY IS, ALTERNATE RECORD KEY IS RRDS File - Use ORGANISATION IS RELATIVE, RELATIVE KEY IS
Printer File - Use ORGANISATION IS SEQUENTIAL. Use RECORDING MODE IS F, BLOCK
CONTAINS 0. (Use RECFM=FBA in JCL DCB).
Q45) What are different file OPEN modes available in COBOL?
A45) Open for INPUT, OUTPUT, I-O, EXTEND.
Q46) What is the mode in which you will OPEN a file for writing? - GS
A46) OUTPUT, EXTEND
Q47) In the JCL, how do you define the files referred to in a subroutine ?
A47) Supply the DD cards just as you would for files referred to in the main program.
Q48) Can you REWRITE a record in an ESDS file? Can you DELETE a record from it?
A48) Can rewrite (record length must be same), but not delete.
Q49) What is file status 92? - GS
A49) Logic error. e.g., a file is opened for input and an attempt is made to write to it.
Q50) What is file status 39 ?
A50) Mismatch in LRECL or BLOCKSIZE or RECFM between your COBOL pgm & the JCL (or the dataset label). You
will get file status 39 on an OPEN.
Q51) What is Static and Dynamic linking ?
A51) In static linking, the called subroutine is link-edited into the calling program , while in dynamic linking, the subroutine
& the main program will exist as separate load modules. You choose static/dynamic linking by choosing either the
DYNAM or NODYNAM link edit option. (Even if you choose NODYNAM, a CALL identifier (as opposed to a
CALL literal), will translate to a DYNAMIC call).
A statically called subroutine will not be in its initial state the next time it is called unless you explicitly use INITIAL
or you do a CANCEL. A dynamically called routine will always be in its initial state.
Q52) What is AMODE(24), AMODE(31), RMODE(24) and RMODE(ANY)? (applicable to only MVS/ESA
Enterprise Server).
A52) These are compile/link edit options. Basically AMODE stands for Addressing mode and RMODE for Residency
mode.
AMODE(24) - 24 bit addressing;
AMODE(31) - 31 bit addressing
AMODE(ANY) - Either 24 bit or 31 bit addressing depending on RMODE.
RMODE(24) - Resides in virtual storage below 16 Meg line. Use this for 31 bit programs that call 24 bit programs.
(OS/VS Cobol pgms use 24 bit addresses only).
RMODE(ANY) - Can reside above or below 16 Meg line.
Q53) What compiler option would you use for dynamic linking?
A53) DYNAM.
Q54) What is SSRANGE, NOSSRANGE ?
A54) These are compiler options with respect to subscript out of range checking. NOSSRANGE is the default and if chosen,
no run time error will be flagged if your index or subscript goes out of the permissible range.
Q55) How do you set a return code to the JCL from a COBOL program?
A55) Move a value to RETURN-CODE register. RETURN-CODE should not be declared in your program.
Q56) How can you submit a job from COBOL programs?
A56) Write JCL cards to a dataset with //xxxxxxx SYSOUT= (A,INTRDR) where 'A' is output class, and dataset should be
opened for output in the program. Define a 80 byte record layout for the file.
Q57) What are the differences between OS VS COBOL and VS COBOL II?
A57) OS/VS Cobol pgms can only run in 24 bit addressing mode, VS Cobol II pgms can run either in 24 bit or 31 bit
addressing modes.
I. Report writer is supported only in OS/VS Cobol.
II. USAGE IS POINTER is supported only in VS COBOL II.
III. Reference modification e.g.: WS-VAR(1:2) is supported only in VS COBOL II.
IV. EVALUATE is supported only in VS COBOL II.
V. Scope terminators are supported only in VS COBOL II.
VI. OS/VS Cobol follows ANSI 74 stds while VS COBOL II follows ANSI 85 stds.
VII. Under CICS Calls between VS COBOL II programs are supported.
Q58) What are the steps you go through while creating a COBOL program executable?
A58) DB2 precompiler (if embedded SQL used), CICS translator (if CICS pgm), Cobol compiler, Link editor. If DB2
program, create plan by binding the DBRMs.
Q59) Can you call an OS VS COBOL pgm from a VS COBOL II pgm ?
A59) In non-CICS environment, it is possible. In CICS, this is not possible.
Q60) What are the differences between COBOL and COBOL II?
A60) There are at least five differences:
COBOL II supports structured programming by using in line Performs and explicit scope terminators, It introduces
new features (EVALUATE, SET. TO TRUE, CALL. BY CONTEXT, etc) It permits programs to be loaded and
addressed above the 16-megabyte line It does not support many old features (READY TRACE, REPORT-WRITER,
ISAM, Etc.), and It offers enhanced CICS support.
Q61) What is an explicit scope terminator?
A61) A scope terminator brackets its preceding verb, e.g. IF .. END-IF, so that all statements between the verb and its scope terminator are grouped together. Other common COBOL II verbs are READ, PERFORM, EVALUATE, SEARCH and STRING.
Q62) What is an in line PERFORM? When would you use it? Anything else to say about it?
A62) The PERFORM and END-PERFORM statements bracket all COBOL II statements between them. The COBOL equivalent is to PERFORM or PERFORM THRU a paragraph. In line PERFORMs work as long as there are no internal GO TOs, not even to an exit. The in line PERFORM for readability should not exceed a page length - often it will reference other PERFORM paragraphs.
Q63) What is the difference between NEXT SENTENCE and CONTINUE?
A63) NEXT SENTENCE gives control to the verb following the next period. CONTINUE gives control to the next verb after the explicit scope terminator. (This is not one of COBOL II's finer implementations). It's safest to use CONTINUE rather than NEXT SENTENCE in COBOL II.
Q64) What COBOL construct is the COBOL II EVALUATE meant to replace?
A64) EVALUATE can be used in place of the nested IF THEN ELSE statements.
Q65) What is the significance of 'above the line' and 'below the line'?
A65) Before IBM introduced MVS/XA architecture in the 1980's a program's virtual storage was limited to 16 megs. Programs compiled with a 24 bit mode can only address 16 Mb of space, as though they were kept under an imaginary storage line. With COBOL II a program compiled with a 31 bit mode can be 'above the 16 Mb line. (This 'below the line', 'above the line' imagery confuses most mainframe programmers, who tend to be a literal minded group.)
Q66) What was removed from COBOL in the COBOL II implementation?
A66) Partial list: REMARKS, NOMINAL KEY, PAGE-COUNTER, CURRENT-DAY, TIME-OF-DAY, STATE, FLOW, COUNT, EXAMINE, EXHIBIT, READY TRACE and RESET TRACE.
Q67) Explain call by context by comparing it to other calls.
A67) The parameters passed in a call by context are protected from modification by the called program. In a normal call they are able to be modified.
Q68) What is the linkage section?
A68) The linkage section is part of a called program that 'links' or maps to data items in the calling program's working storage. It is the part of the called program where these share items are defined.
Q69) What is the difference between a subscript and an index in a table definition?
A69) A subscript is a working storage data definition item, typically a PIC (999) where a value must be moved to the subscript and then incremented or decrements by ADD TO and SUBTRACT FROM statements. An index is a register item that exists outside the program's working storage. You SET an index to a value and SET it UP BY value and DOWN BY value.
Q70) If you were passing a table via linkage, which is preferable - a subscript or an index?
A70) Wake up - you haven't been paying attention! It's not possible to pass an index via linkage. The index is not part of the calling programs working storage. Those of us who've made this mistake, appreciate the lesson more than others.
Q71) Explain the difference between an internal and an external sort, the pros and cons, internal sort syntax etc.
A71) An external sort is not COBOL; it is performed through JCL and PGM=SORT. It is understandable without any code reference. An internal sort can use two different syntax’s: 1.) USING, GIVING sorts are comparable to external sorts with no extra file processing; 2) INPUT PROCEDURE, OUTPUT PROCEDURE sorts allow for data manipulation before and/or after the sort.
Q72) What is the difference between comp and comp-3 usage? Explain other COBOL usage’s.
A72) Comp is a binary usage, while comp-3 indicates packed decimal. The other common usage’s are binary and display. Display is the default.
Q73) When is a scope terminator mandatory?
A73) Scope terminators are mandatory for in-line PERFORMS and EVALUATE statements. For readability, it's recommended coding practice to always make scope terminators explicit.
Q74) In a COBOL II PERFORM statement, when is the conditional tested, before or after the perform execution?
A74) In COBOL II the optional clause WITH TEST BEFORE or WITH TEST AFTER can be added to all perform statements. By default the test is performed before the perform.
Q75) In an EVALUTE statement is the order of the WHEN clauses significant?
A75) Absolutely. Evaluation of the WHEN clauses proceeds from top to bottom and their sequence can determine results.
Q76) What is the default value(s) for an INITIALIZE and what keyword allows for an override of the default.
A76) INITIALIZE moves spaces to alphabetic fields and zeros to alphanumeric fields. The REPLACING option can be used to override these defaults.
Q77) What is SET TO TRUE all about, anyway?
A77) In COBOL II the 88 levels can be set rather than moving their associated values to the related data item. (Web note: This change is not one of COBOL II's better specifications.)
Q78) What is LENGTH in COBOL II?
A78) LENGTH acts like a special register to tell the length of a group or elementary item.
Q79) What is the difference between a binary search and a sequential search? What are the pertinent COBOL
commands?
A79) In a binary search the table element key values must be in ascending or descending sequence. The table is 'halved' to search for equal to, greater than or less than conditions until the element is found. In a sequential search the table is searched from top to bottom, so (ironically) the elements do not have to be in a specific sequence. The binary search is much faster for larger tables, while sequential works well with smaller ones. SEARCH ALL is used for binary searches; SEARCH for sequential.
Q80) What is the point of the REPLACING option of a copy statement?
A80) REPLACING allows for the same copy to be used more than once in the same code by changing the replace value.
ASP,NET
1. Describe the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe in the page loading process.
inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among otherthings.When an ASP.NET request is received (usually a file with .aspx extension), the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe.
2. What’s the difference between Response.Write() andResponse.Output.Write()?
Response.Output.Write() allows you to write formatted output.
3. What methods are fired during the page load?
Init() - when the page is instantiated
Load() - when the page is loaded into server memory
PreRender() - the brief moment before the page is displayed to the user as HTML
Unload() - when page finishes loading.
4. When during the page processing cycle is ViewState available?
After the Init() and before the Page_Load(), or OnLoad() for a control.
5. What namespace does the Web page belong in the .NET Framework class hierarchy?
System.Web.UI.Page
6. Where do you store the information about the user’s locale?
System.Web.UI.Page.Culture
7. What’s the difference between Codebehind="MyCode.aspx.cs"andSrc="MyCode.aspx.cs"?
CodeBehind is relevant to Visual Studio.NET only.
8. What’s a bubbled event?
When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button, row, etc.) is quite tedious. The controls can bubble up theireventhandlers, allowing the main DataGrid event handler to take care of its constituents.
9. Suppose you want a certain ASP.NET function executed on MouseOver for a certain button. Where do you add an event handler?
Add an OnMouseOver attribute to the button. Example:btnSubmit.Attributes.Add("onmouseover","someClientCodeHere();");
10. What data types do the RangeValidator control support?
Integer, String, and Date.
11. Explain the differences between Server-side and Client-side code?
Server-side code executes on the server. Client-side code executes in the client's browser.
12. What type of code (server or client) is found in a Code-Behind class?
The answer is server-side code since code-behind is executed on the server. However, during the code-behind's execution on the server, it can render client-side code such as JavaScript to be processed in the clients browser. But just to be clear, code-behind executes on the server, thus making it server-side code.
13. Should user input data validation occur server-side or client-side? Why?
All user input data validation should occur on the server at a minimum. Additionally, client-side validation can be performed where deemed appropriate and feasable to provide a richer, more responsive experience for the user.
14. What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?
Server.Transfer transfers page processing from one page directly to the next page without making a round-trip back to the client's browser. This provides a faster response with a little less overhead on the server. Server.Transfer does not update the clients urlhistory list or current url. Response.Redirect is used to redirect the user's browser to another page or site. This performas a trip back to the client where the client's browser is redirected to the new page. The user's browser history list is updated to reflect the new address.
15. Can you explain the difference between an ADO.NET Dataset and an ADORecordset?
Valid answers are:
• A DataSet can represent an entire relational database in memory, complete with tables, relations, and views.
• A DataSet is designed to work without any continuing connection to the original data source.
• Data in a DataSet is bulk-loaded, rather than being loaded on demand.
• There's no concept of cursor types in a DataSet.
• DataSets have no current record pointer You can use For Each loops to move through the data.
• You can store many edits in a DataSet, and write them to the original data source in a single operation.
• Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.
16. What is the Global.asax used for?
The Global.asax (including the Global.asax.cs file) is used to implement application and session level events.
17. What are the Application_Start and Session_Start subroutines used for?
This is where you can set the specific variables for the Application and Session objects.
18. Can you explain what inheritance is and an example of when you might use it?
When you want to inherit (use the functionality of) another class. Example: With a base class named Employee, a Manager class could be derived from the Employee base class.
19. Whats an assembly?
Assemblies are the building blocks of the .NET framework. Overview of assemblies from MSDN
20. Describe the difference between inline and code behind.
Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.
21. Explain what a diffgram is, and a good use for one?
The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service.
22. Whats MSIL, and why should my developers need an appreciation of it if at all?
MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL. MSIL also allows the .NET Framework to JIT compile the assembly on the installed computer.
23. Which method do you invoke on the DataAdapter control to load your generated dataset with data?
The Fill() method.
24. Can you edit data in the Repeater control?
No, it just reads the information from its data source.
25. Which template must you provide, in order to display data in a Repeater control?
ItemTemplate.
26. How can you provide an alternating color scheme in a Repeater control?
Use the AlternatingItemTemplate.
27. What property must you set, and what method must you call in your code, in order to bind the data from a data source to the Repeater control?
You must set the DataSource property and call the DataBind method.
28. What base class do all Web Forms inherit from?
The Page class.
29. Name two properties common in every validation control?
ControlToValidate property and Text property.
30. Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box?
DataTextField property.
31. Which control would you use if you needed to make sure the values in two different controls matched?
CompareValidator control.
32. How many classes can a single .NET DLL contain?
It can contain many classes.
Web Service Questions
1. What is the transport protocol you use to call a Web service?
SOAP (Simple Object Access Protocol) is the preferred protocol.
2. True or False: A Web service can only be written in .NET?
False
3. What does WSDL stand for?
Web Services Description Language.
4. Where on the Internet would you look for Web services?
http://www.uddi.org
5. True or False: To test a Web service you must create a Windows application or Web application to consume this service?
False, the web service comes with a test page and it provides HTTP-GET method to test.
State Management Questions
1. What is ViewState?
ViewState allows the state of objects (serializable) to be stored in a hidden field on the page. ViewState is transported to the client and back to the server, and is not stored on the server or any other external source. ViewState is used the retain the state of server-side objects between postabacks.
2. What is the lifespan for items stored in ViewState?
Item stored in ViewState exist for the life of the current page. This includes postbacks(to the same page).
3. What does the "EnableViewState" property do? Why would I want it on or off?
It allows the page to save the users input on a form across postbacks. It saves the server-side values for a given control into ViewState, which is stored as a hidden value on the page before sending the page to the clients browser. When the page is posted back to the server the server control is recreated with the state stored in viewstate.
4. What are the different types of Session state management options available with ASP.NET?
ASP.NET provides In-Process and Out-of-Process state management. In-Process stores the session in memory on the web server. This requires the a "sticky-server" (or no load-balancing) so that the user is always reconnected to the same web server. Out-of-Process Session state management stores data in an external data source. The external data source may be either a SQL Server or a State Server service. Out-of-Process state management requires that all objects stored in session are serializable.
JAVA
What are Encapsulation, Inheritance and Polymorphism?- Encapsulation is the mechanism that binds together code and data it manipulates and keeps both safe from outside interference and misuse. Inheritance is the process by which one object acquires the properties of another object. Polymorphism is the feature that allows one interface to be used for general class actions.
What is OOPs?- Object oriented programming organizes a program around its data, i. e. , objects and a set of well defined interfaces to that data. An object-oriented program can be characterized as data controlling access to code.
What are Class, Constructor and Primitive data types?- Class is a template for multiple objects with similar features and it is a blue print for objects. It defines a type of object according to the data the object can hold and the operations the object can perform. Constructor is a special kind of method that determines how an object is initialized when created. Primitive data types are 8 types and they are: byte, short, int, long, float, double, boolean, char.
What is an Object and how do you allocate memory to it?- Object is an instance of a class and it is a software unit that combines a structured set of data with a set of operations for inspecting and manipulating that data. When an object is created using new operator, memory is allocated to it.
What are methods and how are they defined?- Methods are functions that operate on instances of classes in which they are defined. Objects can communicate with each other using methods and can call methods in other classes. Method definition has four parts. They are name of the method, type of object or primitive type the method returns, a list of parameters and the body of the method. A method’s signature is a combination of the first three parts mentioned above.
www.prepareinterview.com
What is the use of bin and lib in JDK?- Bin contains all tools such as javac, appletviewer, awt tool, etc., whereas lib contains API and all packages.
What is casting?- Casting is used to convert the value of one type to another.
How many ways can an argument be passed to a subroutine and explain them?- An argument can be passed in two ways. They are passing by value and passing by reference. Passing by value: This method copies the value of an argument into the formal parameter of the subroutine. Passing by reference: In this method, a reference to an argument (not the value of the argument) is passed to the parameter.
What are different types of access modifiers?- public: Any thing declared as public can be accessed from anywhere. private: Any thing declared as private can’t be seen outside of its class. protected: Any thing declared as protected can be accessed by classes in the same package and subclasses in the other packages. default modifier : Can be accessed only to classes in the same package.
What is final, finalize() and finally?- final : final keyword can be used for class, method and variables. A final class cannot be subclassed and it prevents other programmers from subclassing a secure class to invoke insecure methods. A final method can’t be overridden. A final variable can’t change from its initialized value. finalize() : finalize() method is used just before an object is destroyed and can be called just prior to garbage collection. finally : finally, a key word used in exception handling, creates a block of code that will be executed after a try/catch block has completed and before the code following the try/catch block. The finally block will execute whether or not an exception is thrown. For example, if a method opens a file upon exit, then you will not want the code that closes the file to be bypassed by the exception-handling mechanism. This finally keyword is designed to address this contingency.
What is UNICODE?- Unicode is used for internal representation of characters and strings and it uses 16 bits to represent each other.
What is Garbage Collection and how to call it explicitly?- When an object is no longer referred to by any variable, java automatically reclaims memory used by that object. This is known as garbage collection. System. gc() method may be used to call it explicitly.
What is finalize() method?- finalize () method is used just before an object is destroyed and can be called just prior to garbage collection.
What are Transient and Volatile Modifiers?- Transient: The transient modifier applies to variables only and it is not stored as part of its object’s Persistent state. Transient variables are not serialized. Volatile: Volatile modifier applies to variables only and it tells the compiler that the variable modified by volatile can be changed unexpectedly by other parts of the program.
What is method overloading and method overriding?- Method overloading: When a method in a class having the same method name with different arguments is said to be method overloading. Method overriding : When a method in a class having the same method name with same arguments is said to be method overriding.
What is meant by Inheritance and what are its advantages?- Inheritance is the process of inheriting all the features from a class. The advantages of inheritance are reusability of code and accessibility of variables and methods of the super class by subclasses.
What modifiers may be used with top-level class?- public, abstract and final can be used for top-level class.
What are inner class and anonymous class?- Inner class : classes defined in other classes, including those defined in methods are called inner classes. An inner class can have any accessibility including private. Anonymous class : Anonymous class is a class defined inside a method without a name and is instantiated and declared in the same place and cannot have explicit constructors.
What is a package?- A package is a collection of classes and interfaces that provides a high-level layer of access protection and name space management.
What is a reflection package?- java. lang. reflect package has the ability to analyze itself in runtime.
Software testing
. Software Testing is more Oriented to Detecting the defects or often equated to finding bugs. Testing is a process of executing a software system to determine whether it matches its specification and executes in its intended environment under controlled conditiions. The controlled conditions should include both normal and abnormal conditions. Testing should intentionally attempt to make things go wrong to determine if things happen when they shouldn't or things don't happen when they should.
SQA: - Software QA involves the entire software development PROCESS - monitoring and improving the process, making sure that any agreed-upon standards and procedures are followed, and ensuring that problems are found and dealt with. It is oriented to 'prevention'.
Stop Testing: -
Testing is potentially endless. We can not test till all the defects are unearthed and removed -- it is simply impossible. At some point, we have to stop testing and ship the software. The question is when.
Realistically, testing is a trade-off between budget, time and quality. It is driven by profit models. The pessimistic, and unfortunately most often used approach is to stop testing whenever some, or any of the allocated resources -- time, budget, or test cases -- are exhausted. The optimistic stopping rule is to stop testing when either reliability meets the requirement, or the benefit from continuing testing cannot justify the testing cost. [Yang95] This will usually require the use of reliability models to evaluate and predict reliability of the software under test. Each evaluation requires repeated running of the following cycle: failure data gathering -- modeling -- prediction. This method does not fit well for ultra-dependable systems, however, because the real field failure data will take too long to accumulate.
For Verification & Validation (V&V)
Just as topic Verification and Validation indicated, another important purpose of testing is verification and validation (V&V). Testing can serve as metrics. It is heavily used as a tool in the V&V process. Testers can make claims based on interpretations of the testing results, which either the product works under certain situations, or it does not work. We can also compare the quality among different products under the same specification, based on results from the same test.
2. What is the purpose of software testing?
The purpose of software testing is
a. To demonstrate that the product performs each function intended;
b. To demonstrate that the internal operation of the product performs according to specification and all internal components have been adequately exercised;
c. To increase our confidence in the proper functioning of the software.
d. To show the product is free from defect.
e. All of the above.
3. Types of Levels: -
COMPATIBILITY TESTING. Testing to ensure compatibility of an application or Web site with different browsers, OSs, and hardware platforms. Compatibility testing can be performed manually or can be driven by an automated functional or regression test suite.
CONFORMANCE TESTING. Verifying implementation conformance to industry standards. Producing tests for the behavior of an implementation to be sure it provides the portability, interoperability, and/or compatibility a standard defines.
FUNCTIONAL TESTING. Validating an application or Web site conforms to its specifications and correctly performs all its required functions. This entails a series of tests which perform a feature by feature validation of behavior, using a wide range of normal and erroneous input data. This can involve testing of the product's user interface, APIs, database management, security, installation, networking, etcF testing can be performed on an automated or manual basis using black box or white box methodologies.
LOAD TESTING. Load testing is a generic term covering Performance Testing and Stress Testing.
PERFORMANCE TESTING. Performance testing can be applied to understand your application or WWW site's scalability, or to benchmark the performance in an environment of third party products such as servers and middleware for potential purchase. This sort of testing is particularly useful to identify performance bottlenecks in high use applications. Performance testing generally involves an automated test suite as this allows easy simulation of a variety of normal, peak, and exceptional load conditions.
REGRESSION TESTING. Similar in scope to a functional test, a regression test allows a consistent, repeatable validation of each new release of a product or Web site. Such testing ensures reported product defects have been corrected for each new release and that no new quality problems were introduced in the maintenance process. Though regression testing can be performed manually an automated test suite is often used to reduce the time and resources needed to perform the required testing.
SMOKE TESTING. A quick-and-dirty test that the major functions of a piece of software work without bothering with finer details. Originated in the hardware testing practice of turning on a new piece of hardware for the first time and considering it a success if it does not catch on fire.
STRESS TESTING. Testing conducted to evaluate a system or component at or beyond the limits of its specified requirements to determine the load under which it fails and how. A graceful degradation under load leading to non-catastrophic failure is the desired result. Often Stress Testing is performed using the same process as Performance Testing but employing a very high level of simulated load.
UNIT TESTING. Functional and reliability testing in an Engineering environment. Producing tests for the behavior of components of a product to ensure their correct behavior prior to system integration.
Black Box Testing
Black box testing methods focus on the functional requirements of the software. Tests sets are derived that fully exercise all functional requirements. This strategy tends to be applied during the latter part of the lifecycle.
Tests are designed to answer questions such as:
1) How is functional validity tested?
2) What classes of input make good test cases?
3) Is the system particularly sensitive to certain input values?
4) How are the boundaries of data classes isolated?
5) What data rates or volumes can the system tolerate?
6) What effect will specific combinations of data have on system operation?
Equivalence Partitioning: -
This method divides the input of a program into classes of data. Test case design is based on defining an equivalent class for a particular input. An equivalence class represents a set of valid and invalid input values.
Guidelines for equivalence partitioning -
1) If an input condition specifies a range, one valid and two invalid equivalence classes are defined.
2) If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.
3) If an input condition specifies a member of a set, one valid and one invalid equivalence class are defined.
4) If an input condition is boolean, one valid and one invalid class are defined.
Boundary Value Analysis: -
Boundary value analysis is complementary to equivalence partitioning. Rather than selecting arbitrary input values to partition the equivalence class, the test case designer chooses values at the extremes of the class. Furthermore, boundary value analysis also encourages test case designers to look at output conditions and design test cases for the extreme conditions in output.
Guidelines for boundary value analysis -
1) If an input condition specifies a range bounded by values a and b, test cases should be designed with values a and b, and values just above and just below and b.
2) If an input condition specifies a number of values, test cases should be developed that exercise the minimum and maximum numbers. Values above and below the minimum and maximum are also tested.
3) Apply the above guidelines to output conditions. For example, if the requirement specifies the production of an table as output then you want to choose input conditions that produce the largest and smallest possible table.
4) For internal data structures be certain to design test cases to exercise the data structure at its boundary. For example, if the software includes the maintenance of a personnel list, then you should ensure the software is tested with conditions where the list size is 0, 1 and maximum (if constrained).
Cause-Effect Graphs
A weakness of the two methods is that do not consider potential combinations of input/output conditions. Cause-effect graphs connect input classes (causes) to output classes (effects) yielding a directed graph.
Guidelines for cause-effect graphs -
1) Causes and effects are listed for a modules and an identifier is assigned to each.
2) A cause-effect graph is developed (special symbols are required).
3) The graph is converted to a decision table.
4) Decision table rules are converted to test cases.
We can not test quality directly, but we can test related factors to make quality visible. Quality has three sets of factors -- functionality, engineering, and adaptability. These three sets of factors can be thought of as dimensions in the software quality space. Each dimension may be broken down into its component factors and considerations at successively lower levels of detail.
Performance testing
Not all software systems have specifications on performance explicitly. But every system will have implicit performance requirements. The software should not take infinite time or infinite resource to execute. "Performance bugs" sometimes are used to refer to those design problems in software that cause the system performance to degrade.
Reliability testing
Software reliability refers to the probability of failure-free operation of a system. It is related to many aspects of software, including the testing process. Directly estimating software reliability by quantifying its related factors can be difficult. Testing is an effective sampling method to measure software reliability. Guided by the operational profile, software testing (usually black-box testing) can be used to obtain failure data, and an estimation model can be further used to analyze the data to estimate the present reliability and predict future reliability. Therefore, based on the estimation, the developers can decide whether to release the software, and the users can decide whether to adopt and use the software. Risk of using software can also be assessed based on reliability information. [Hamlet94] advocates that the primary goal of testing should be to measure the dependability of tested software.
Security testing
Software quality, reliability and security are tightly coupled. Flaws in software can be exploited by intruders to open security holes. With the development of the Internet, software security problems are becoming even more severe.
Many critical software applications and services have integrated security measures against malicious attacks. The purpose of security testing of these systems include identifying and removing software flaws that may potentially lead to security violations, and validating the effectiveness of security measures. Simulated security attacks can be performed to find vulnerabilities.
TESTING means "quality control"
* QUALITY CONTROL measures the quality of a product
* QUALITY ASSURANCE measures the quality of processes used to create a quality product.
Beta testing is typically conducted by end users of a software product who are not paid a salary for their efforts.
Acceptance Testing
Testing the system with the intent of confirming readiness of the product and customer acceptance.
Ad Hoc Testing
Testing without a formal test plan or outside of a test plan. With some projects this type of testing is carried out as an adjunct to formal testing. If carried out by a skilled tester, it can often find problems that are not caught in regular testing. Sometimes, if testing occurs very late in the development cycle, this will be the only kind of testing that can be performed. Sometimes ad hoc testing is referred to as exploratory testing.
Alpha Testing
Testing after code is mostly complete or contains most of the functionality and prior to users being involved. Sometimes a select group of users are involved. More often this testing will be performed in-house or by an outside testing firm in close cooperation with the software engineering department.
Automated Testing
Software testing that utilizes a variety of tools to automate the testing process and when the importance of having a person manually testing is diminished. Automated testing still requires a skilled quality assurance professional with knowledge of the automation tool and the software being tested to set up the tests.
Beta Testing
Testing after the product is code complete. Betas are often widely distributed or even distributed to the public at large in hopes that they will buy the final product when it is released.
Black Box Testing
Testing software without any knowledge of the inner workings, structure or language of the module being tested. Black box tests, as most other kinds of tests, must be written from a definitive source document, such as a specification or requirements document..
Compatibility Testing
Testing used to determine whether other system software components such as browsers, utilities, and competing software will conflict with the software being tested.
Configuration Testing
Testing to determine how well the product works with a broad range of hardware/peripheral equipment configurations as well as on different operating systems and software.
Functional Testing
Testing two or more modules together with the intent of finding defects, demonstrating that defects are not present, verifying that the module performs its intended functions as stated in the specification and establishing confidence that a program does what it is supposed to do.
Independent Verification and Validation (IV&V)
The process of exercising software with the intent of ensuring that the software system meets its requirements and user expectations and doesn't fail in an unacceptable manner. The individual or group doing this work is not part of the group or organization that developed the software. A term often applied to government work or where the government regulates the products, as in medical devices.
Installation Testing
Testing with the intent of determining if the product will install on a variety of platforms and how easily it installs.
Integration Testing
Testing two or more modules or functions together with the intent of finding interface defects between the modules or functions. Testing completed at as a part of unit or functional testing, and sometimes, becomes its own standalone test phase. On a larger level, integration testing can involve a putting together of groups of modules and functions with the goal of completing and verifying that the system meets the system requirements. (see system testing)
Load Testing
Testing with the intent of determining how well the product handles competition for system resources. The competition may come in the form of network traffic, CPU utilization or memory allocation.
Performance Testing
Testing with the intent of determining how quickly a product handles a variety of events. Automated test tools geared specifically to test and fine-tune performance are used most often for this type of testing.
Pilot Testing
Testing that involves the users just before actual release to ensure that users become familiar with the release contents and ultimately accept it. Often is considered a Move-to-Production activity for ERP releases or a beta test for commercial products. Typically involves many users, is conducted over a short period of time and is tightly controlled. (see beta testing)
Regression Testing
Testing with the intent of determining if bug fixes have been successful and have not created any new problems. Also, this type of testing is done to ensure that no degradation of baseline functionality has occurred.
Security Testing
Testing of database and network software in order to keep company data and resources secure from mistaken/accidental users, hackers, and other malevolent attackers.
Software Testing
The process of exercising software with the intent of ensuring that the software system meets its requirements and user expectations and doesn't fail in an unacceptable manner. The organization and management of individuals or groups doing this work is not relevant. This term is often applied to commercial products such as internet applications. (contrast with independent verification and validation)
Stress Testing
Testing with the intent of determining how well a product performs when a load is placed on the system resources that nears and then exceeds capacity.
System Integration Testing
Testing a specific hardware/software installation. This is typically performed on a COTS (commerical off the shelf) system or any other system comprised of disparent parts where custom configurations and/or unique installations are the norm.
White Box Testing
Testing in which the software tester has knowledge of the inner workings, structure and language of the software, or at least its purpose.
Difference Between Verification & Validation: -
- Verification is about answering the question "Does the system function properly?" or "Have we built the system right?"
- Validation is about answering the question "Is the product what the customer wanted?" or "Have we built the right system?"
This definition indicates that Validation could be the same thing as Acceptance Test (or at least very similar).
I have often described Verification and Validation processes in the same way, ie:
1. Plan the test (output Test Plan)
2. Specify the test (output Test Specification)
3. Perform the test (output Test Log and/or Test Report
Verification & Validation
Verification typically involves reviews and meetings to evaluate documents, plans, code, requirements, and specifications. This can be done with checklists, issues lists, walkthroughs, and inspection meetings. Validation typically involves actual testing and takes place after verifications are completed. The term 'IV & V' refers to Independent Verification and Validation.
JAVA Conceptual Questions
What is the .NET Framework?
The Microsoft .NET Framework is a platform for building, deploying, and running Web Services and applications. It provides a highly productive, standards-based, multi-language environment for integrating existing investments with next-generation applications and services as well as the agility to solve the challenges of deployment and operation of Internet-scale applications. The .NET Framework consists of three main parts: the common language runtime, a hierarchical set of unified class libraries, and a componentized version of Active Server Pages called ASP.NET.
Runtime Technical Questions
Terminology
What is the common language runtime (CLR)?
The common language runtime is the execution engine for .NET Framework applications.
It provides a number of services, including the following:
o Code management (loading and execution)
o Application memory isolation
o Verification of type safety
o Conversion of IL to native code
o Access to metadata (enhanced type information)
o Managing memory for managed objects
o Enforcement of code access security
o Exception handling, including cross-language exceptions
o Interoperation between managed code, COM objects, and pre-existing DLLs (unmanaged code and data)
o Automation of object layout
o Support for developer services (profiling, debugging, and so on)
What is the common type system (CTS)?
The common type system is a rich type system, built into the common language runtime, that supports the types and operations found in most programming languages. The common type system supports the complete implementation of a wide range of programming languages.
What is the Common Language Specification (CLS)?
The Common Language Specification is a set of constructs and constraints that serves as a guide for library writers and compiler writers. It allows libraries to be fully usable from any language supporting the CLS, and for those languages to integrate with each other. The Common Language Specification is a subset of the common type system. The Common Language Specification is also important to application developers who are writing code that will be used by other developers. When developers design publicly accessible APIs following the rules of the CLS, those APIs are easily used from all other programming languages that target the common language runtime.
What is the Microsoft Intermediate Language (MSIL)?
MSIL is the CPU-independent instruction set into which .NET Framework programs are compiled. It contains instructions for loading, storing, initializing, and calling methods on objects.
Combined with metadata and the common type system, MSIL allows for true cross-language integration.
Prior to execution, MSIL is converted to machine code. It is not interpreted.
What is managed code and managed data?
Managed code is code that is written to target the services of the common language runtime (see What is the Common Language Runtime?). In order to target these services, the code must provide a minimum level of information (metadata) to the runtime. All C#, Visual Basic .NET, and JScript .NET code is managed by default. Visual Studio .NET C++ code is not managed by default, but the compiler can produce managed code by specifying a command-line switch (/CLR).
Closely related to managed code is managed data—data that is allocated and de-allocated by the common language runtime's garbage collector. C#, Visual Basic, and JScript .NET data is managed by default. C# data can, however, be marked as unmanaged through the use of special keywords. Visual Studio .NET C++ data is unmanaged by default (even when using the /CLR switch), but when using Managed Extensions for C++, a class can be marked as managed by using the __gc keyword. As the name suggests, this means that the memory for instances of the class is managed by the garbage collector. In addition, the class becomes a full participating member of the .NET Framework community, with the benefits and restrictions that brings. An example of a benefit is proper interoperability with classes written in other languages (for example, a managed C++ class can inherit from a Visual Basic class). An example of a restriction is that a managed class can only inherit from one base class.
Assemblies
What is an assembly?
An assembly is the primary building block of a .NET Framework application. It is a collection of functionality that is built, versioned, and deployed as a single implementation unit (as one or more files). All managed types and resources are marked either as accessible only within their implementation unit, or as accessible by code outside that unit.
Assemblies are self-describing by means of their manifest, which is an integral part of every assembly. The manifest:
o Establishes the assembly identity (in the form of a text name), version, culture, and digital signature (if the assembly is to be shared across applications).
o Defines what files (by name and file hash) make up the assembly implementation.
o Specifies the types and resources that make up the assembly, including which are exported from the assembly.
o Itemizes the compile-time dependencies on other assemblies.
o Specifies the set of permissions required for the assembly to run properly.
This information is used at run time to resolve references, enforce version binding policy, and validate the integrity of loaded assemblies. The runtime can determine and locate the assembly for any running object, since every type is loaded in the context of an assembly. Assemblies are also the unit at which code access security permissions are applied. The identity evidence for each assembly is considered separately when determining what permissions to grant the code it contains.
The self-describing nature of assemblies also helps makes zero-impact install and XCOPY deployment feasible.
What are private assemblies and shared assemblies?
A private assembly is used only by a single application, and is stored in that application's install directory (or a subdirectory therein). A shared assembly is one that can be referenced by more than one application. In order to share an assembly, the assembly must be explicitly built for this purpose by giving it a cryptographically strong name (referred to as a strong name). By contrast, a private assembly name need only be unique within the application that uses it.
By making a distinction between private and shared assemblies, we introduce the notion of sharing as an explicit decision. Simply by deploying private assemblies to an application directory, you can guarantee that that application will run only with the bits it was built and deployed with. References to private assemblies will only be resolved locally to the private application directory.
There are several reasons you may elect to build and use shared assemblies, such as the ability to express version policy. The fact that shared assemblies have a cryptographically strong name means that only the author of the assembly has the key to produce a new version of that assembly. Thus, if you make a policy statement that says you want to accept a new version of an assembly, you can have some confidence that version updates will be controlled and verified by the author. Otherwise, you don't have to accept them.
For locally installed applications, a shared assembly is typically explicitly installed into the global assembly cache (a local cache of assemblies maintained by the .NET Framework). Key to the version management features of the .NET Framework is that downloaded code does not affect the execution of locally installed applications. Downloaded code is put in a special download cache and is not globally available on the machine even if some of the downloaded components are built as shared assemblies.
The classes that ship with the .NET Framework are all built as shared assemblies.
If I want to build a shared assembly, does that require the overhead of signing and managing key pairs?
Building a shared assembly does involve working with cryptographic keys. Only the public key is strictly needed when the assembly is being built. Compilers targeting the .NET Framework provide command line options (or use custom attributes) for supplying the public key when building the assembly. It is common to keep a copy of a common public key in a source database and point build scripts to this key. Before the assembly is shipped, the assembly must be fully signed with the corresponding private key. This is done using an SDK tool called SN.exe (Strong Name).
Strong name signing does not involve certificates like Authenticode does. There are no third party organizations involved, no fees to pay, and no certificate chains. In addition, the overhead for verifying a strong name is much less than it is for Authenticode. However, strong names do not make any statements about trusting a particular publisher. Strong names allow you to ensure that the contents of a given assembly haven't been tampered with, and that the assembly loaded on your behalf at run time comes from the same publisher as the one you developed against. But it makes no statement about whether you can trust the identity of that publisher.
What is the difference between a namespace and an assembly name?
A namespace is a logical naming scheme for types in which a simple type name, such as MyType, is preceded with a dot-separated hierarchical name. Such a naming scheme is completely under the control of the developer. For example, types MyCompany.FileAccess.A and MyCompany.FileAccess.B might be logically expected to have functionality related to file access. The .NET Framework uses a hierarchical naming scheme for grouping types into logical categories of related functionality, such as the Microsoft® ASP.NET application framework, or remoting functionality. Design tools can make use of namespaces to make it easier for developers to browse and reference types in their code. The concept of a namespace is not related to that of an assembly. A single assembly may contain types whose hierarchical names have different namespace roots, and a logical namespace root may span multiple assemblies. In the .NET Framework, a namespace is a logical design-time naming convenience, whereas an assembly establishes the name scope for types at run time.
Application Deployment and Isolation
What options are available to deploy my .NET applications?
The .NET Framework simplifies deployment by making zero-impact install and XCOPY deployment of applications feasible. Because all requests are resolved first to the private application directory, simply copying an application's directory files to disk is all that is needed to run the application. No registration is required.
This scenario is particularly compelling for Web applications, Web Services, and self-contained desktop applications. However, there are scenarios where XCOPY is not sufficient as a distribution mechanism. An example is when the application has little private code and relies on the availability of shared assemblies, or when the application is not locally installed (but rather downloaded on demand). For these cases, the .NET Framework provides extensive code download services and integration with the Windows Installer. The code download support provided by the .NET Framework offers several advantages over current platforms, including incremental download, code access security (no more Authenticode dialogs), and application isolation (code downloaded on behalf of one application doesn't affect other applications). The Windows Installer is another powerful deployment mechanism available to .NET applications. All of the features of Windows Installer, including publishing, advertisement, and application repair will be available to .NET applications in Windows Installer 2.0.
I've written an assembly that I want to use in more than one application. Where do I deploy it?
Assemblies that are to be used by multiple applications (for example, shared assemblies) are deployed to the global assembly cache. In the prerelease and Beta builds, use the /i option to the GACUtil SDK tool to install an assembly into the cache:
gacutil /i myDll.dll
Windows Installer 2.0, which ships with Windows XP and Visual Studio .NET will be able to install assemblies into the global assembly cache.
How can I see what assemblies are installed in the global assembly cache?
The .NET Framework ships with a Windows shell extension for viewing the assembly cache. Navigating to %windir%\assembly with the Windows Explorer activates the viewer.
What is an application domain?
An application domain (often AppDomain) is a virtual process that serves to isolate an application. All objects created within the same application scope (in other words, anywhere along the sequence of object activations beginning with the application entry point) are created within the same application domain. Multiple application domains can exist in a single operating system process, making them a lightweight means of application isolation.
An OS process provides isolation by having a distinct memory address space. While this is effective, it is also expensive, and does not scale to the numbers required for large web servers. The Common Language Runtime, on the other hand, enforces application isolation by managing the memory use of code running within the application domain. This ensures that it does not access memory outside the boundaries of the domain. It is important to note that only type-safe code can be managed in this way (the runtime cannot guarantee isolation when unsafe code is loaded in an application domain).
Garbage Collection
What is garbage collection?
Garbage collection is a mechanism that allows the computer to detect when an object can no longer be accessed. It then automatically releases the memory used by that object (as well as calling a clean-up routine, called a "finalizer," which is written by the user). Some garbage collectors, like the one used by .NET, compact memory and therefore decrease your program's working set.
How does non-deterministic garbage collection affect my code?
For most programmers, having a garbage collector (and using garbage collected objects) means that you never have to worry about deallocating memory, or reference counting objects, even if you use sophisticated data structures. It does require some changes in coding style, however, if you typically deallocate system resources (file handles, locks, and so forth) in the same block of code that releases the memory for an object. With a garbage collected object you should provide a method that releases the system resources deterministically (that is, under your program control) and let the garbage collector release the memory when it compacts the working set.
Can I avoid using the garbage collected heap?
All languages that target the runtime allow you to allocate class objects from the garbage-collected heap. This brings benefits in terms of fast allocation, and avoids the need for programmers to work out when they should explicitly 'free' each object.
The CLR also provides what are called ValueTypes—these are like classes, except that ValueType objects are allocated on the runtime stack (rather than the heap), and therefore reclaimed automatically when your code exits the procedure in which they are defined. This is how "structs" in C# operate.
Managed Extensions to C++ lets you choose where class objects are allocated. If declared as managed Classes, with the __gc keyword, then they are allocated from the garbage-collected heap. If they don't include the __gc keyword, they behave like regular C++ objects, allocated from the C++ heap, and freed explicitly with the "free" method.
For additional information about Garbage Collection see:
o Garbage Collection: Automatic Memory Management in the Microsoft .NET Framework
o Garbage Collection, Part 2: Automatic Memory Management in the Microsoft .NET Framework
Remoting
How do in-process and cross-process communication work in the Common Language Runtime?
There are two aspects to in-process communication: between contexts within a single application domain, or across application domains. Between contexts in the same application domain, proxies are used as an interception mechanism. No marshaling/serialization is involved. When crossing application domains, we do marshaling/serialization using the runtime binary protocol.
Cross-process communication uses a pluggable channel and formatter protocol, each suited to a specific purpose.
o If the developer specifies an endpoint using the tool soapsuds.exe to generate a metadata proxy, HTTP channel with SOAP formatter is the default.
o If a developer is doing explicit remoting in the managed world, it is necessary to be explicit about what channel and formatter to use. This may be expressed administratively, through configuration files, or with API calls to load specific channels. Options are:
HTTP channel w/ SOAP formatter (HTTP works well on the Internet, or anytime traffic must travel through firewalls)
TCP channel w/ binary formatter (TCP is a higher performance option for local-area networks (LANs))
When making transitions between managed and unmanaged code, the COM infrastructure (specifically, DCOM) is used for remoting. In interim releases of the CLR, this applies also to serviced components (components that use COM+ services). Upon final release, it should be possible to configure any remotablecomponent.
Distributed garbage collection of objects is managed by a system called "leased based lifetime." Each object has a lease time, and when that time expires, the object is disconnected from the remoting infrastructure of the CLR. Objects have a default renew time-the lease is renewed when a successful call is made from the client to the object. The client can also explicitly renew the lease.
Interoperability
Can I use COM objects from a .NET Framework program?
Yes. Any COM component you have deployed today can be used from managed code, and in common cases the adaptation is totally automatic.
Specifically, COM components are accessed from the .NET Framework by use of a runtime callable wrapper (RCW). This wrapper turns the COM interfaces exposed by the COM component into .NET Framework-compatible interfaces. For OLE automation interfaces, the RCW can be generated automatically from a type library. For non-OLE automation interfaces, a developer may write a custom RCW and manually map the types exposed by the COM interface to .NET Framework-compatible types.
Can .NET Framework components be used from a COM program?
Yes. Managed types you build today can be made accessible from COM, and in the common case the configuration is totally automatic. There are certain new features of the managed development environment that are not accessible from COM. For example, static methods and parameterized constructors cannot be used from COM. In general, it is a good idea to decide in advance who the intended user of a given type will be. If the type is to be used from COM, you may be restricted to using those features that are COM accessible.
Depending on the language used to write the managed type, it may or may not be visible by default.
Specifically, .NET Framework components are accessed from COM by using a COM callable wrapper (CCW). This is similar to an RCW (see previous question), but works in the opposite direction. Again, if the .NET Framework development tools cannot automatically generate the wrapper, or if the automatic behavior is not what you want, a custom CCW can be developed.
Can I use the Win32 API from a .NET Framework program?
Yes. Using platform invoke, .NET Framework programs can access native code libraries by means of static DLL entry points.
Here is an example of C# calling the Win32 MessageBox function:
using System;
using System.Runtime.InteropServices;
class MainApp
{
[DllImport("user32.dll", EntryPoint="MessageBox")]
public static extern int MessageBox(int hWnd, String strMessage, String strCaption,uint uiType);
public static void Main()
{
MessageBox( 0, "Hello, this is PInvoke in operation!", ".NET", 0 );
}
}
Security
What do I have to do to make my code work with the security system?
Usually, not a thing—most applications will run safely and will not be exploitable by malicious attacks. By simply using the standard class libraries to access resources (like files) or perform protected operations (such as a reflection on private members of a type), security will be enforced by these libraries. The one simple thing application developers may want to do is include a permission request (a form of declarative security) to limit the permissions their code may receive (to only those it requires). This also ensures that if the code is allowed to run, it will do so with all the permissions it needs.
Only developers writing new base class libraries that expose new kinds of resources need to work directly with the security system. Instead of all code being a potential security risk, code access security constrains this to a very small bit of code that explicitly overrides the security system.
Why does my code get a security exception when I run it from a network shared drive?
Default security policy gives only a restricted set of permissions to code that comes from the local intranet zone. This zone is defined by the Internet Explorer security settings, and should be configured to match the local network within an enterprise. Since files named by UNC or by a mapped drive (such as with the NET USE command) are being sent over this local network, they too are in the local intranet zone.
The default is set for the worst case of an unsecured intranet. If your intranet is more secure you can modify security policy (with the .NET Framework Configuration tool or the CASPol tool) to grant more permissions to the local intranet, or to portions of it (such as specific machine share names).
How do I make it so that code runs when the security system is stopping it?
Security exceptions occur when code attempts to perform actions for which it has not been granted permission. Permissions are granted based on what is known about code; especially its location. For example, code run from the Internet is given fewer permissions than that run from the local machine because experience has proven that it is generally less reliable. So, to allow code to run that is failing due to security exceptions, you must increase the permissions granted to it. One simple way to do so is to move the code to a more trusted location (such as the local file system). But this won't work in all cases (web applications are a good example, and intranet applications on a corporate network are another). So, instead of changing the code's location, you can also change security policy to grant more permissions to that location. This is done using either the .NET Framework Configuration tool or the code access security policy utility (caspol.exe). If you are the code's developer or publisher, you may also digitally sign it and then modify security policy to grant more permissions to code bearing that signature. When taking any of these actions, however, remember that code is given fewer permissions because it is not from an identifiably trustworthy source—before you move code to your local machine or change security policy, you should be sure that you trust the code to not perform malicious or damaging actions.
How do I administer security for my machine? For an enterprise?
The .NET Framework includes the .NET Framework Configuration tool, an MMC snap-in (mscorcfg.msc), to configure several aspects of the CLR including security policy. The snap-in not only supports administering security policy on the local machine, but also creates enterprise policy deployment packages compatible with System Management Server and Group Policy. A command line utility, CASPol.exe, can also be used to script policy changes on the computer. In order to run either tool, in a command prompt, change the current directory to the installation directory of the .NET Framework (located in %windir%\Microsoft.Net\Framework\v1.0.2914.16\) and type mscorcfg.msc or caspol.exe.
How does evidence-based security work with Windows 2000 security?
Evidence-based security (which authorizes code) works together with Windows 2000 security (which is based on log on identity). For example, to access a file, managed code must have both the code access security file permission and must also be running under a log on identity that has NTFS file access rights. The managed libraries that are included with the .NET Framework also provide classes for role-based security. These allow the application to work with Windows log on identities and user groups.
What is interface and its use?- Interface is similar to a class which may contain method’s signature only but not bodies and it is a formal set of method and constant declarations that must be defined by the class that implements it. Interfaces are useful for: a)Declaring methods that one or more classes are expected to implement b)Capturing similarities between unrelated classes without forcing a class relationship. c)Determining an object’s programming interface without revealing the actual body of the class.
What is an abstract class?- An abstract class is a class designed with implementation gaps for subclasses to fill in and is deliberately incomplete.
What is a cloneable interface and how many methods does it contain?- It is not having any method because it is a TAGGED or MARKER interface.
Can you have an inner class inside a method and what variables can you access?- Yes, we can have an inner class inside a method and final variables can be accessed.
What is multithreading and what are the methods for inter-thread communication and what is the class in which these methods are defined?- Multithreading is the mechanism in which more than one thread run independent of each other within the process. wait (), notify () and notifyAll() methods can be used for inter-thread communication and these methods are in Object class. wait() : When a thread executes a call to wait() method, it surrenders the object lock and enters into a waiting state. notify() or notifyAll() : To remove a thread from the waiting state, some other thread must make a call to notify() or notifyAll() method on the same object.
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What is the class and interface in java to create thread and which is the most advantageous method?- Thread class and Runnable interface can be used to create threads and using Runnable interface is the most advantageous method to create threads because we need not extend thread class here.
What are the states associated in the thread?- Thread contains ready, running, waiting and dead states.
What is synchronization?- Synchronization is the mechanism that ensures that only one thread is accessed the resources at a time.
When you will synchronize a piece of your code?- When you expect your code will be accessed by different threads and these threads may change a particular data causing data corruption.
What is deadlock?- When two threads are waiting each other and can’t precede the program is said to be deadlock.
What is daemon thread and which method is used to create the daemon thread?- Daemon thread is a low priority thread which runs intermittently in the back ground doing the garbage collection operation for the java runtime system. setDaemon method is used to create a daemon thread.
Are there any global variables in Java, which can be accessed by other part of your program?-No, it is not the main method in which you define variables. Global variables is not possible because concept of encapsulation is eliminated here.
What is an applet?- Applet is a dynamic and interactive program that runs inside a web page displayed by a java capable browser.
How does applet recognize the height and width?- Using getParameters() method.
When do you use codebase in applet?- When the applet class file is not in the same directory, codebase is used.
What is the lifecycle of an applet?- init() method - Can be called when an applet is first loaded start() method - Can be called each time an applet is started. paint() method - Can be called when the applet is minimized or maximized. stop() method - Can be used when the browser moves off the applet’s page. destroy() method - Can be called when the browser is finished with the applet.
How do you set security in applets?- using setSecurityManager() method
What is an event and what are the models available for event handling?- An event is an event object that describes a state of change in a source. In other words, event occurs when an action is generated, like pressing button, clicking mouse, selecting a list, etc. There are two types of models for handling events and they are: a) event-inheritance model and b) event-delegation model
What are the advantages of the model over the event-inheritance model?- The event-delegation model has two advantages over the event-inheritance model. They are: a)It enables event handling by objects other than the ones that generate the events. This allows a clean separation between a component’s design and its use. b)It performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to be repeatedly process unhandled events as is the case of the event-inheritance.
What is source and listener?- source : A source is an object that generates an event. This occurs when the internal state of that object changes in some way. listener : A listener is an object that is notified when an event occurs. It has two major requirements. First, it must have been registered with one or more sources to receive notifications about specific types of events. Second, it must implement methods to receive and process these notifications.
What is adapter class?- An adapter class provides an empty implementation of all methods in an event listener interface. Adapter classes are useful when you want to receive and process only some of the events that are handled by a particular event listener interface. You can define a new class to act listener by extending one of the adapter classes and implementing only those events in which you are interested. For example, the MouseMotionAdapter class has two methods, mouseDragged()and mouseMoved(). The signatures of these empty are exactly as defined in the MouseMotionListener interface. If you are interested in only mouse drag events, then you could simply extend MouseMotionAdapter and implement mouseDragged() .
What is meant by controls and what are different types of controls in AWT?- Controls are components that allow a user to interact with your application and the AWT supports the following types of controls: Labels, Push Buttons, Check Boxes, Choice Lists, Lists, Scrollbars, Text Components. These controls are subclasses of Component.
What is a layout manager and what are different types of layout managers available in java AWT?- A layout manager is an object that is used to organize components in a container. The different layouts are available are FlowLayout, BorderLayout, CardLayout, GridLayout and GridBagLayout.
How are the elements of different layouts organized?- FlowLayout: The elements of a FlowLayout are organized in a top to bottom, left to right fashion. BorderLayout: The elements of a BorderLayout are organized at the borders (North, South, East and West) and the center of a container. CardLayout: The elements of a CardLayout are stacked, on top of the other, like a deck of cards. GridLayout: The elements of a GridLayout are of equal size and are laid out using the square of a grid. GridBagLayout: The elements of a GridBagLayout are organized according to a grid. However, the elements are of different size and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes.
Which containers use a Border layout as their default layout?- Window, Frame and Dialog classes use a BorderLayout as their layout.
GENERAL APTITUDE
A man starts his walking at 3PM from point A, he walks at the rate of 4km/hr in plains and 3km/hr in hills to reach the point B. During his return journey he walks at the rate of 6km/hr in hills and 4km/hr in plains and reaches the point A at 9PM.What is the distance between A and B?
Ans: 12km
Solution:
T1+T2=6
T1-time for forward journey,
T2-time for return journey
D1+D2=forward /return distance
D1-distance in plains
D2-distance in hills
D1/4 +D2/3=T1 (forward time)
D1/4 +D2/6=T2 (return time)
Adding we will get D1+D2=12 km
2. A boy asks his father, " what is the age of grand father?". Father replied " He is x years old in x^2 years", and also said, "we are talking about 20th century". what is the year of birth of grand father?
Ans: 1892
3. A boy travels in a scooter after covering 2/3rd of the distance the wheel got punctured he covered the remaining distance by walk. Walking time is twice that of the time the boy’s riding time. How many times the riding speed as that of the walking speed?
Ans: 4 times.
4. In a Knockout tournament 51 teams are participated, every team thrown out of the tournament if they lost twice. How many matches to be held to choose the winner?
Ans: 101 matches
5. A man sold 2 pens. Initial cost of each pen was Rs. 12. If he sell it together one at 25% profit and another 20% loss. Find the amount of loss or gain, if he sells them separately.
Ans: 60 Paise gain
6. Find the 3 digit no. whose last digit is the square root of the first digit and second digit is the sum of the other two digits.
Ans: 462
7. Meera was playing with her brother using 55 blocks. She gets bored playing and starts arranging the blocks such that the no. of blocks in each row is one less than that in the lower row. Find how many were there in the bottom most row?
Ans: 10
8. Two people are playing with a pair of dies. Instead of numbers, the dies have different colors on their sides. The first person wins if the same color appears on both the dies and the second person wins if the colors are different. The odds of their winning are equal. If the first dice has 5 red sides and 1 blue side, find the color(s) on the second one.
Ans: 3 Red, 3 Blue
9. A person travels in a car with uniform speed. He observes the milestone, which has 2 digits. After one hour he observes another milestone with same digits reversed. After another hour he observes another milestone with same 2 digits separated by 0. Find the speed of the car?
Ans : 45
10. Three persons A, B &C went for a robbery in different directions and they theft one horse, one mule and one camel. They were caught by the police and when interrogated gave the following statements
A: B has stolen the horse
B: I didn't rob anything.
C: both A & B are false and B has stolen the mule.
The person who has stolen the horse always tell the truth and
The person who has stolen the camel always tell the lie.
Find who has stolen which animal?
Ans:
A- camel
B- mule
C- horse
11. One quarter of the time till now from midnight and half of the time remaining from now up to midnightadds to the present time. What is the present time?
Ans: 9:36AM
12. After world war II three departments did as follows First department gave some tanks to 2nd &3rd departments equal to the number they are having. Then 2nd department gave some tanks to 1st & 3rd departments equal to the number they are having. Then 3rd department gave some tanks to 2nd &1st departments equal to the number they are having. Then each department has 24 tanks. Find the initial number of tanks of each department?
Ans :
A-39
B-21
C-12
13. A, B, C, D&E are having their birthdays on consecutive days of the week not necessarily in the same order. A 's birthday comes before G's as many days as B's birthday comes after E's. D is older than E by 2 days. This time G's birthday came on Wednesday. Then find the day of each of their birthdays?
Ans:
Birthday of D on SUNDAY
Birthday of B on MONDAY
Birthday of E on TUESDAY
Birthday of G on WEDNESDAY
Birthday of A on THURSDAY
14. A girl 'A' told to her friend about the size and color of a snake she has seen in the beach. It is one of the colors brown/black/green and one of the sizes 35/45/55.
If it were not green or if it were not of length 35 it is 55.
If it were not black or if it were not of length 45 it is 55.
If it were not black or if it were not of length 35 it is 55.
a) What is the color of the snake?
b) What is the length of the snake?
Ans:
a) brown
b) 55
15. There are 2 persons each having same amount of marbles in the beginning. after that 1 person gain 20 more from second person n he eventually lose two third of it during the play n the second person now have 4 times marble of what 1st person is having now. find out how much marble did each had in the beginning.
Ans - 100 each
16. A lady was out for shopping. she spent half of her money in buying A and gave 1 dollar to bagger. fathershe spent half of her remaining money and gave 2 dollar to charity. further she spent half of remaining money n gave 3 dollar to some children. now she has left with 1 dollar. how much she had in the beginning?
Ans: $42
17. There are certain diamonds in a shop.
1 thief stole half of diamonds and 2 more.
2 thief stole half of remaining and 2 more
3. same as above
4 same as above.
5 came nothing was left for that.
how many diamonds was there???
Ans: 60 diamonds
18. There are three friends A B C.
1. Either A or B is oldest
2. Either C is oldest or A is youngest.
Who is Youngest and who is Oldest?
Ans: A is youngest n B is oldest.
19. Father says my son is five times older than my daughter. my wife is 5 times older that my son. I am twice old from my wife and altogether (sum of our ages) is equal to my mother 's age and she is celebrating her 81 birthday. so what is my son's age?
Ans: 5 years.
20. Fodder, Wheat and Rice often eat dinner out.
a) each orders either coffee or tea after dinner.
b) if fodder orders coffee, then Wheat orders the drink that Rice orders
c) if Wheat orders coffee, then fodder orders the drink that Rice does not order
d) if Rice orders tea, then fodder orders the drink that Wheat orders
which person/persons always orders the same drink after dinner ?
Ans: Fodder
21. We are given 100 pieces of a puzzle. If fixing two components together is counted as 1 move ( acomponent can be one piece or an already fixed set of pieces), how many moves do we need to fix the entire puzzle.
Ans: 99
22. Two guys work at some speed...After some time one guy realizes he has done only half of the other guy completed which is equal to half of what is left !
So how much faster than the other is this guy supposed to do to finish with the first...
Ans: one and half times or 3/2
23. There is a square cabbage patch. He told his sister that i have a larger patch than last year and hence 211 more cabbages this year. Then how many cabbages I have this year.?
Ans:106*106=11236
24. There are three guesses on the color of a mule
1 says: its not black
2 says: its brown or grey
3 says: its brown
At least one of them is wrong and one of them is true.....Then what’s the color of mule?
Ans: Grey
25. There are two containers on a table. A and B . A is half full of wine, while B, which is twice A's size, is one quarter full of wine . Both containers are filled with water and the contents are poured into a third container C. What portion of container C's mixture is wine ?
Ans:33.33%
26. A man was on his way to a marriage in a car with a constant speed. After 2 hours one of the tier is punctured and it took 10 minutes to replace it. After that they traveled with a speed of 30 miles/hr and reached the marriage 30 minutes late to the scheduled time. The driver told that they would be late by 15 minutes only if the 10 minutes was not waste. Find the distance between the two towns?
Ans: 120 miles
27. Farmer Jones sold a pair of cows for Rs. 210 , On one he made a profit of ten percent and on the other he lost ten percent. Although he made a profit of five percent. How many did each cow originally cost him?
Ans:150,50
28. I spent one-sixth of my age as a boy and one-12th in youth, remarked the boss "spent one-seventh and five years in matrimony". My son born just after that period was elected as a governor 4 years back when he was half of my present age. What is the age of the boss?
Ans: 84
29. A girl had several dollars with her. she went out for shopping and spent half of them in shopping mall, being generous she had given 1 dollar to the beggar. After that she went for lunch and spent the half of the remaining and gave 2 dollars as tip to the waiter. Then she went to watch a movie and spent the half of remaining dollars and gave autorikshaw-wala 3 dollars. This left her with only 1 dollar. How many dollars did she had with her at the beginning.
Ans:$42.
30. A bargain hunter bought some plates for $ 1.30 from a sale on Saturday, where price 2cents was marked off at each article .On Monday she went to return them at regular prices, and bought some cups and saucers from that much amount of money only. The normal price of plate were equal to the price of 'one cup and one saucer'. In total she bought 16 items more than previous. saucers were only of 3 cents hence she brought 10 saucers more than the cups, How many cups and saucers she bought and at what price?
Ans: 8,18 Price: 12,3.
31. Mr. T has a wrong weighing pan. One arm is lengthier than other.1 kilogram on left balances 8 melons on right.1 kilogram on right balances 2 melons on left. If all melons are equal in weight, what is the weight of a single melon?
Ans:200 gms
32. A card board of 34 * 14 has to be attached to a wooden box and a total of 35 pins are to be used on the each side of the cardbox. Find the total number of pins used .
Ans: 210
33. Last Year my cousin came to my place and we played a game where the loosing one has to give one chocolate to the person who won the game .At the end of the vacation, i.e. the day my cousin was leaving she counted number of games that i won an she won. At last she gave me a total of 8 chocolates even though she won about 12 games. Find the number of games that we played.
Ans: 20
34. Here is a five digit number. The fifth digit is one fourth of the third digit and one half of the fourth digit. Third digit is one half of the first digit. second digit is 5 more than the fifth digit.
What is that 5 digit no.?
Ans: 86421
35. A boy goes to school from his house. On one fourth of his way to school, he crosses a
machinery station. And on one third of his way to school, he crosses a Railway station.
He crossed the machinery station at 7:30 and he crosses the Railway station at 7:35.
when does he leave the house & when does he reach the school ? (5M)
Ans: 7:15 - 8:15
36. Four persons A,B,C,D were there. All were of different weights. All Four gave a
statement. Among the four statements only the person who is lightest in weight of all
others gave a true statement.
A Says : B is heavier than D.
B Says : A is heavier than C.
C Says : I am heavier than D.
D Says : C is heavier than B.
Ans: ACDB.
37. A man was traveling to a place 30 miles away from starting point. he was speeding at 60 miles/hr. but when he came back, his car got breakdown and half an hour was wasted in repairing that. altogether he took 1 hr for return journey. Find the avg. speed of the whole journey.
Ans:60 miles/hour.
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