What is DCLGEN ?
DCLGEN stands for declarations generator; it is a facility to generate DB2 sql data structures in COBOL or PL/I programs.
How do you leave the cursor open after issuing a COMMIT? (for DB2 2.3 or above only)
Use WITH HOLD option in DECLARE CURSOR statement. But, it has not effect in psuedo-conversational CICS programs.
Give the COBOL definition of a VARCHAR field.
A VARCHAR column REMARKS would be defined as follows:
... 10 REMARKS.
49 REMARKS-LEN PIC S9(4) USAGE COMP.
49 REMARKS-TEXT PIC X(1920).
What is the physical storage length of each of the following DB2 data types: DATE, TIME, TIMESTAMP?
DATE: 4bytes
TIME: 3bytes
TIMESTAMP: 10bytes
What is the COBOL picture clause of the following DB2 data types: DATE, TIME, TIMESTAMP?
DATE: PIC X(10)
TIME : PIC X(08)
TIMESTAMP: PIC X(26)
What is the COBOL picture clause for a DB2 column defined as DECIMAL(11,2)? - GS
PIC S9(9)V99 COMP-3.
Note: In DECIMAL(11,2), 11 indicates the size of the data type and 2 indicates the precision.
What is DCLGEN ? - GS
DeCLarations GENerator: used to create the host language copy books for the table definitions. Also creates the DECLARE table.
What are the contents of a DCLGEN? - GS
EXEC SQL DECLARE TABLE statement which gives the layout of the table/view in terms of DB2 datatypes.
A host language copy book that gives the host variable definitions for the column names.
Is it mandatory to use DCLGEN? If not, why would you use it at all? - GS
It is not mandatory to use DCLGEN. Using DCLGEN, helps detect wrongly spelt column names etc. during the pre-compile stage itself (because of the DECLARE TABLE ). DCLGEN being a tool, would generate accurate host variable definitions for the table reducing chances of error.
Is DECLARE TABLE in DCLGEN necessary? Why it used?
It not necessary to have DECLARE TABLE statement in DCLGEN. This is used by the pre-compiler to validate the table-name, view-name, column name etc., during pre-compile.
Will precompile of an DB2-COBOL program bomb, if DB2 is down?
No. Because the precompiler does not refer to the DB2 catalogue tables.
How is a typical DB2 batch program executed ?
There are two methods of executing a DB2-batch program
1. Use DSN utility to run a DB2 batch program from native TSO. An example is shown:
DSN SYSTEM(DSP3)
RUN PROGRAM(EDD470BD) PLAN(EDD470BD) LIB('EDGS01T.OBJ.LOADLIB')
END
2. Use IKJEFT01 utility program to run the above DSN command in a JCL. Q13) Assuming that a site's standard is that pgm name = plan name, what is the easiest way to find out which programs are affected by change in a table's structure?
Query the catalogue tables SYSPLANDEP and SYSPACKDEP.
Name some fields from SQLCA.
SQLCODE, SQLERRM, SQLERRD
How can you quickly find out the number of rows updated after an update statement?
Check the value stored in SQLERRD(3).
What is EXPLAIN? - GS
EXPLAIN is used to display the access path as determined by the optimizer for a SQL statement. It can be used in SPUFI (for single SQL statement) or in BIND step (for embedded SQL). The results of EXPLAIN is stored in U.PLAN_TABLE where U is the authorization id of the user
What do you need to do before you do EXPLAIN?
Make sure that the PLAN_TABLE is created under the AUTHID.
Where is the output of EXPLAIN stored? - GS
In USERID.PLAN_TABLE
EXPLAIN has output with MATCHCOLS = 0. What does it mean? - GS
A nonmatching index scan if ACCESSTYPE = I.
How do you do the EXPLAIN of a dynamic SQL statement?
There are two methods to achieve this:
1. Use SPUFI or QMF to EXPLAIN the dynamic SQL statement
2. Include EXPLAIN command in the embedded dynamic SQL statements
How do you simulate the EXPLAIN of an embedded SQL statement in SPUFI/QMF? Give an example with a host variable in WHERE clause)
Use a question mark in place of a host variable (or an unknown value). For instance,
SELECT EMP_NAME FROM EMP WHERE EMP_SALARY > ?
What are the isolation levels possible ? - GS
CS: Cursor Stability
RR: Repeatable Read
What is the difference between CS and RR isolation levels?
CS: Releases the lock on a page after use
RR: Retains all locks acquired till end of transaction
When do you specify the isolation level? How?
During the BIND process(ISOLATION LEVEL is a parameter for the bind process). ISOLATION ( CS/RR )...
I use CS and update a page. Will the lock be released after I am done with that page?
No.
What are the various locking levels available?
PAGE, TABLE, TABLESPACE
How does DB2 determine what lock-size to use?
There are three methods to determine the lock-size. They are:
1. Based on the lock-size given while creating the tablespace
2. Programmer can direct the DB2 what lock-size to use
3. If lock-size ANY is specified, DB2 usually choses a lock-size of PAGE
What are the disadvantages of PAGE level lock?
High resource utilization if large updates are to be done
What is lock escalation?
Promoting a PAGE lock-size to table or tablespace lock-size when a transaction has aquired more locks than specified in NUMLKTS. Locks should be taken on objects in single tablespace for escalation to occur.
What are the various locks available?
SHARE, EXCLUSIVE, UPDATE
Can I use LOCK TABLE on a view?
No. To lock a view, take lock on the underlying tables.
What is ALTER ? - GS
SQL command used to change the definition of DB2 objects.
What is a DBRM, PLAN ?
DBRM: Data Base Request Module, has the SQL statements extracted from the host language program by the pre-compiler. PLAN: A result of the BIND process. It has the executable code for the SQL statements in the DBRM.
Determine the point at which DB2 acquires or releases locks against table and tablespaces, including intent locks.
What else is there in the PLAN apart from the access path? - GS
PLAN has the executable code for the SQL statements in the host program
What happens to the PLAN if index used by it is dropped?
Plan is marked as invalid. The next time the plan is accessed, it is rebound.
What are PACKAGES ? - GS
They contain executable code for SQL statements for one DBRM.
What are the advantages of using a PACKAGE?
The advantages of using PACKAGE are:
1. Avoid having to bind a large number of DBRM members into a plan
2. Avoid cost of a large bind
3. Avoid the entire transaction being unavailable during bind and automatic rebind of a plan
4. Minimize fallback complexities if changes result in an error.
What is a collection?
A user defined name that is the anchor for packages. It has not physical existence. Main usage is to group packages.
In SPUFI suppose you want to select maximum of 1000 rows, but the select returns only 200 rows. What are the 2 SQLCODEs that are returned? - GS
+100 (for successful completion of the query), 0 (for successful COMMIT if AUTOCOMMIT is set to Yes).
How would you print the output of an SQL statement from SPUFI? - GS
Print the output dataset.
Lot of updates have been done on a table due to which indexes have gone haywire. What do you do?
Looks like index page split has occurred. DO a REORG of the indexes.
What is dynamic SQL? - GS
Dynamic SQL is a SQL statement created at program execution time.
When is the access path determined for dynamic SQL? - GS
At run time, when the PREPARE statement is issued.
Suppose I have a program which uses a dynamic SQL and it has been performing well till now. Off late, I find that the performance has deteriorated. What happened? - GS
There may be one of the following reasons:
Probably RUN STATS is not done and the program is using a wrong index due to incorrect stats.
Probably RUNSTATS is done and optimizer has chosen a wrong access path based on the latest statistics.
How does DB2 store NULL physically?
As an extra-byte prefix to the column value. Physically, the null prefix is Hx '00' if the value is present and Hex 'FF' if it is not.
How do you retrieve the data from a nullable column? - GS
Use null indicators. Syntax ... INTO :HOSTVAR:NULLIND
What is the picture clause of the null indicator variable? - GS
S9(4) COMP.
What does it mean if the null indicator has -1, 0, -2? - GS
-1 : the field is null; 0 : the field is not null; -2 : the field value is truncated
How do you insert a record with a nullable column?
To insert a NULL, move -1 to the null indicator, To insert a valid value, move 0 to the null indicator
DB2 (part-2) interview question and answers
What is DB2 (IBM Database 2)?
DB2 is a subsystem of the MVS operating system. It is a Database Management System (DBMS) for that operating system.
What is an access path?
The path that is used to get to data specified in SQL statements.
What is an alias?
It is an alternate name that can be used in SQL statements to refer to a table or view in the same or remote DB2 subsystem.
Explain what a plan is?
Plan is a DB2 object (produced during the bind process) that associates one or more database request modules with a plan name.
What is a DB2 bind?
Bind is a process that builds “access paths” to DB2 tables. A bind uses the Database Request Modules(s) (DBRM(s)) from the DB2 pre-compile step as input and produces an application plan. It also checks the user’s authority and validates the SQL statements in the DBRM(s).
What information is used as input to the bind process?
The database request module produced during the pre-compile. The SYSIBM.SYSSTMT table of the DB2 catalog.
What is meant by the attachment facility?
The attachment facility is an interface between DB2 and TSO, IMS/VS, CICS, or batch address spaces. It allows application programs to access DB2.
What is meant by AUTO COMMIT?
AUTO COMMIT is a SPUFI option that commits the effects of SQL statements automatically if they are successfully executed.
What is a base table?
A base table is a real table - a table that physically exists in that there are physical stored records.
What is the function of buffer manager?
The buffer manager is the DB2 component responsible for physically transferring data between an external medium and (virtual) storage (performs the actual I/O operations). It minimizes the amount of physical I/O actually performed with sophisticated buffering techniques(i.e., read-ahead buffering and look-aside buffering).
What is a buffer pool?
A buffer pool is main storage that is reserved to satisfy the buffering requirements for one or more tablespaces or indexes, and is made up of either 4K or 32K pages.
How many buffer pools are there in DB2?
There are four buffer pools: BP0, BP1, BP2, and BP32.
On the create tablespace, what does the CLOSE parameter do?
CLOSE physically closes the tablespace when no one is working on the object. DB2 (release 2.3) will logically close tablespaces.
What is a clustering index?
It is a type of index that (1) locates table rows and (2) determines how rows are grouped together in the tablespace.
What will the COMMIT accomplish?
COMMIT will allow data changes to be permanent. This then permits the data to be accessed by other units of work. When a COMMIT occurs, locks are freed so other applications can reference the just committed data.
What is meant by concurrency?
Concurrency is what allows more than one DB2 application process to access the same data at essentially the same time. Problems may occur, such as lost updates, access to uncommitted data, and un-repeatable reads.
What is cursor stability?
It is cursor stability that “tells” DB2 that database values read by this application are protected only while they are being used. (Changed values are protected until this application reaches the commit point). As soon as a program moves from one row to another, other programs may read or the first row.
What is the function of the Data Manager?
The Data Manager is a DB2 component that manager the physical databases. It invokes other system components, as necessary, to perform detailed functions such as locking, logging, and physical I/O operations (such as search, retrieval, update, and index maintenance).
What is a Database Request Module(DBRM)?
A DBRM is a DB2 component created by the DB2 pre-compiler containing the SQL source statements extracted from the application program. DBRMs are input to the bind process.
What is a data page?
A data page is a unit of retrievable data, either 4K or 32K (depending on how the table is defined), containing user or catalog information.
What are data types?
They are attributes of columns, literals, and host variables. The data types are SMALLINT, INTEGER, FLOAT, DECIMAL, CHAR, VARCHAR, DATE and TIME.
What is Declaration Generator(DCLGEN)?
DCLGEN is a facility that is used to generate SQL statements that describe a table or view. These table or view descriptions are then used to check the validity of other SQL statements at precompile time. The table or view declares are used by the DB2I utility DCLGEN to build a host language structure, which is used by the DB2 precompiler to verify that correct column names and data types have been specified in the SQL statement.
What does DSNDB07 database do?
DSNDB07 is where DB2 does its sorting. It includes DB2’s sort work area and external storage.
What will the FREE command do to a plan?
It will drop(delete) that existing plan.
What is a host variable?
This is a data item that is used in an SQL statement to receive a value or to supply a value. It must be preceded by a colon (:) to tell DB2 that the variable is not a column name.
What will the DB2 optimizer do?
The optimizer is a DB2 component that processes SQL statements and selects the access paths.
What is a page?
This is the unit of storage within a table space or indexspace that is accessed by DB2.
What is pagespace?
Pagespace refers to either to an unpartitioned table, to an index space, or to a single partition of a partitioned table of index space.
What is a predicate?
A predicate is an element of a search condition that expresses or implies a comparison operation.
What is a Resource Control Table(RCT)? Describe its characteristics.
The RCT is a table that is defined to a DB2/CICS region. It contains control characteristics which are assembled via the DSNCRCT macros. The RCT matches the CICS transaction ID to its associated DB2 authorization ID and plan ID(CICS attachment facility).
Where are plans stored?
Each plan is defined uniquely in the SYSIBM.SYSPLANS table to correspond to the transaction (s) that are to execute that plan.
What is meant by repeatable read?
When an application program executes with repeatable read protection, rows referenced by the program can’t be changed by other programs until the program reaches a commit point.
Describe what a storage group(STOGROUP) is?
A STOGROUP is a named collection of DASD volumes to be used by tablespaces and index spaces of databases. The volumes of STOGROUP must be of the same device type.
How would you move a tablespace (using STOGROUP) to a different DASD volume allocated to that tablespace?
If the tablespace used is only allocated to that STOGROUP:
- ALTER STOGROUP - add volume (new) delete volume(old)
- REORG TABLESPACE or RECOVER TABLESPACE
Create a new STOGROUP that points to the new volume. ALTER the tablespace and REORG or RECOVER the
tablespace.
What is the format (internal layout) of “TIMESTAMP”?
This is a seven part value that consists of a date (yymmdd) and time(hhmmss and microseconds).
What is meant by a unit of recovery?
This is a sequence of operations within a unit of work(i.e., work done between commit points).
Can DASD types assigned to storage groups be intermixed(i.e., 3350s and 3380s)?
No
What are the three types of page locks that can be held?
Exclusive, update, and share.
Can DB2 be accessed by TSO users? If yes, which command is used to invoke DB2?
DB2 can be invoked by TSO users by using the DSN RUN command.
How are write I/Os from the buffer pool executed?
Asynchronously.
What is a DB2 catalog?
The DB2 catalog is a set of tables that contain information about all of the DB2 objects(tables, views, plans etc.).
In which column of which DB2 catalog would you find the length of the rows for all tables?
In the RECLENGTH column of SYSIBM.SYSTABLES
What information is held in SYSIBM.SYSCOPY?
The SYSIBM.SYSCOPY table contains information about image copies made of the tablespaces.
What information is contained in a SYSCOPY entry?
Included is the name of the database, the table space name, and the image copy type(full or incremental etc.,) as well as the date and time each copy was made.
What information can you find in SYSIBM.SYSLINKS table?
The SYSIBM.SYSLINKS table contains information about the links between tables created by referential constraints.
Where would you find information about the type of database authority held by the user?
SYSIBM.SYSDBAUTH.
Where could you look if you had a question about whether a column has been defined as an index?
This information can be found in SYSIBM.SYSINDEXES.
Once you create a view, where would information about the view be stored?
When a view is created, system information about the view is stored in SYSIBM.SYSVIEWS.
What is the SQL Communications Area and what are some of its key fields?
It is a data structure that must be included in any host-language program using SQL. It is used to pass feedback about the sql operations to the program. Fields are return codes, error messages, handling codes and warnings.
DB2 is a subsystem of the MVS operating system. It is a Database Management System (DBMS) for that operating system.
What is an access path?
The path that is used to get to data specified in SQL statements.
What is an alias?
It is an alternate name that can be used in SQL statements to refer to a table or view in the same or remote DB2 subsystem.
Explain what a plan is?
Plan is a DB2 object (produced during the bind process) that associates one or more database request modules with a plan name.
What is a DB2 bind?
Bind is a process that builds “access paths” to DB2 tables. A bind uses the Database Request Modules(s) (DBRM(s)) from the DB2 pre-compile step as input and produces an application plan. It also checks the user’s authority and validates the SQL statements in the DBRM(s).
What information is used as input to the bind process?
The database request module produced during the pre-compile. The SYSIBM.SYSSTMT table of the DB2 catalog.
What is meant by the attachment facility?
The attachment facility is an interface between DB2 and TSO, IMS/VS, CICS, or batch address spaces. It allows application programs to access DB2.
What is meant by AUTO COMMIT?
AUTO COMMIT is a SPUFI option that commits the effects of SQL statements automatically if they are successfully executed.
What is a base table?
A base table is a real table - a table that physically exists in that there are physical stored records.
What is the function of buffer manager?
The buffer manager is the DB2 component responsible for physically transferring data between an external medium and (virtual) storage (performs the actual I/O operations). It minimizes the amount of physical I/O actually performed with sophisticated buffering techniques(i.e., read-ahead buffering and look-aside buffering).
What is a buffer pool?
A buffer pool is main storage that is reserved to satisfy the buffering requirements for one or more tablespaces or indexes, and is made up of either 4K or 32K pages.
How many buffer pools are there in DB2?
There are four buffer pools: BP0, BP1, BP2, and BP32.
On the create tablespace, what does the CLOSE parameter do?
CLOSE physically closes the tablespace when no one is working on the object. DB2 (release 2.3) will logically close tablespaces.
What is a clustering index?
It is a type of index that (1) locates table rows and (2) determines how rows are grouped together in the tablespace.
What will the COMMIT accomplish?
COMMIT will allow data changes to be permanent. This then permits the data to be accessed by other units of work. When a COMMIT occurs, locks are freed so other applications can reference the just committed data.
What is meant by concurrency?
Concurrency is what allows more than one DB2 application process to access the same data at essentially the same time. Problems may occur, such as lost updates, access to uncommitted data, and un-repeatable reads.
What is cursor stability?
It is cursor stability that “tells” DB2 that database values read by this application are protected only while they are being used. (Changed values are protected until this application reaches the commit point). As soon as a program moves from one row to another, other programs may read or the first row.
What is the function of the Data Manager?
The Data Manager is a DB2 component that manager the physical databases. It invokes other system components, as necessary, to perform detailed functions such as locking, logging, and physical I/O operations (such as search, retrieval, update, and index maintenance).
What is a Database Request Module(DBRM)?
A DBRM is a DB2 component created by the DB2 pre-compiler containing the SQL source statements extracted from the application program. DBRMs are input to the bind process.
What is a data page?
A data page is a unit of retrievable data, either 4K or 32K (depending on how the table is defined), containing user or catalog information.
What are data types?
They are attributes of columns, literals, and host variables. The data types are SMALLINT, INTEGER, FLOAT, DECIMAL, CHAR, VARCHAR, DATE and TIME.
What is Declaration Generator(DCLGEN)?
DCLGEN is a facility that is used to generate SQL statements that describe a table or view. These table or view descriptions are then used to check the validity of other SQL statements at precompile time. The table or view declares are used by the DB2I utility DCLGEN to build a host language structure, which is used by the DB2 precompiler to verify that correct column names and data types have been specified in the SQL statement.
What does DSNDB07 database do?
DSNDB07 is where DB2 does its sorting. It includes DB2’s sort work area and external storage.
What will the FREE command do to a plan?
It will drop(delete) that existing plan.
What is a host variable?
This is a data item that is used in an SQL statement to receive a value or to supply a value. It must be preceded by a colon (:) to tell DB2 that the variable is not a column name.
What will the DB2 optimizer do?
The optimizer is a DB2 component that processes SQL statements and selects the access paths.
What is a page?
This is the unit of storage within a table space or indexspace that is accessed by DB2.
What is pagespace?
Pagespace refers to either to an unpartitioned table, to an index space, or to a single partition of a partitioned table of index space.
What is a predicate?
A predicate is an element of a search condition that expresses or implies a comparison operation.
What is a Resource Control Table(RCT)? Describe its characteristics.
The RCT is a table that is defined to a DB2/CICS region. It contains control characteristics which are assembled via the DSNCRCT macros. The RCT matches the CICS transaction ID to its associated DB2 authorization ID and plan ID(CICS attachment facility).
Where are plans stored?
Each plan is defined uniquely in the SYSIBM.SYSPLANS table to correspond to the transaction (s) that are to execute that plan.
What is meant by repeatable read?
When an application program executes with repeatable read protection, rows referenced by the program can’t be changed by other programs until the program reaches a commit point.
Describe what a storage group(STOGROUP) is?
A STOGROUP is a named collection of DASD volumes to be used by tablespaces and index spaces of databases. The volumes of STOGROUP must be of the same device type.
How would you move a tablespace (using STOGROUP) to a different DASD volume allocated to that tablespace?
If the tablespace used is only allocated to that STOGROUP:
- ALTER STOGROUP - add volume (new) delete volume(old)
- REORG TABLESPACE or RECOVER TABLESPACE
Create a new STOGROUP that points to the new volume. ALTER the tablespace and REORG or RECOVER the
tablespace.
What is the format (internal layout) of “TIMESTAMP”?
This is a seven part value that consists of a date (yymmdd) and time(hhmmss and microseconds).
What is meant by a unit of recovery?
This is a sequence of operations within a unit of work(i.e., work done between commit points).
Can DASD types assigned to storage groups be intermixed(i.e., 3350s and 3380s)?
No
What are the three types of page locks that can be held?
Exclusive, update, and share.
Can DB2 be accessed by TSO users? If yes, which command is used to invoke DB2?
DB2 can be invoked by TSO users by using the DSN RUN command.
How are write I/Os from the buffer pool executed?
Asynchronously.
What is a DB2 catalog?
The DB2 catalog is a set of tables that contain information about all of the DB2 objects(tables, views, plans etc.).
In which column of which DB2 catalog would you find the length of the rows for all tables?
In the RECLENGTH column of SYSIBM.SYSTABLES
What information is held in SYSIBM.SYSCOPY?
The SYSIBM.SYSCOPY table contains information about image copies made of the tablespaces.
What information is contained in a SYSCOPY entry?
Included is the name of the database, the table space name, and the image copy type(full or incremental etc.,) as well as the date and time each copy was made.
What information can you find in SYSIBM.SYSLINKS table?
The SYSIBM.SYSLINKS table contains information about the links between tables created by referential constraints.
Where would you find information about the type of database authority held by the user?
SYSIBM.SYSDBAUTH.
Where could you look if you had a question about whether a column has been defined as an index?
This information can be found in SYSIBM.SYSINDEXES.
Once you create a view, where would information about the view be stored?
When a view is created, system information about the view is stored in SYSIBM.SYSVIEWS.
What is the SQL Communications Area and what are some of its key fields?
It is a data structure that must be included in any host-language program using SQL. It is used to pass feedback about the sql operations to the program. Fields are return codes, error messages, handling codes and warnings.
Cobal and Cobal II interview question and answers
Name the divisions in a COBOL program ?.
IDENTIFICATION DIVISION, ENVIRONMENT DIVISION, DATA DIVISION, PROCEDURE DIVISION.
What are the different data types available in COBOL?
Alpha-numeric (X), alphabetic (A) and numeric (9).
What does the INITIALIZE verb do? - GS
Alphabetic, Alphanumeric fields & alphanumeric edited items are set to SPACES. Numeric, Numeric edited items set to ZERO. FILLER , OCCURS DEPENDING ON items left untouched.
What is 77 level used for ?
Elementary level item. Cannot be subdivisions of other items (cannot be qualified), nor can they be subdivided themselves.
What is 88 level used for ?
For condition names.
What is level 66 used for ?
For RENAMES clause.
What does the IS NUMERIC clause establish ?
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 - .
How do you define a table/array in COBOL?
ARRAYS.
05 ARRAY1 PIC X(9) OCCURS 10 TIMES.
05 ARRAY2 PIC X(6) OCCURS 20 TIMES INDEXED BY WS-INDEX.
Can the OCCURS clause be at the 01 level?
No.
What is the difference between index and subscript? - GS
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.
What is the difference between SEARCH and SEARCH ALL? - GS
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.
What should be the sorting order for SEARCH ALL? - GS
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).
What is binary search?
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.
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?
Must use compiler option SSRANGE if you want array bounds checking. Default is NOSSRANGE.
How do you sort in a COBOL program? Give sort file definition, sort statement syntax and meaning. - GS
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.
How do you define a sort file in JCL that runs the COBOL program?
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.
What is the difference between performing a SECTION and a PARAGRAPH? - GS
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.
What is the use of EVALUATE statement? - GS
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.
What are the different forms of EVALUATE statement?
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
How do you come out of an EVALUATE statement? - GS
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.
In an EVALUATE statement, can I give a complex condition on a when clause?
Yes.
What is a scope terminator? Give examples.
Scope terminator is used to mark the end of a verb e.g. EVALUATE, END-EVALUATE; IF, END-IF.
How do you do in-line PERFORM? - GS
PERFORM ......
END-PERFORM
When would you use in-line perform?
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 Para and use
PERFORM Para name rather than in-line perform.
What is the difference between CONTINUE & NEXT SENTENCE ?
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 ***
IDENTIFICATION DIVISION, ENVIRONMENT DIVISION, DATA DIVISION, PROCEDURE DIVISION.
What are the different data types available in COBOL?
Alpha-numeric (X), alphabetic (A) and numeric (9).
What does the INITIALIZE verb do? - GS
Alphabetic, Alphanumeric fields & alphanumeric edited items are set to SPACES. Numeric, Numeric edited items set to ZERO. FILLER , OCCURS DEPENDING ON items left untouched.
What is 77 level used for ?
Elementary level item. Cannot be subdivisions of other items (cannot be qualified), nor can they be subdivided themselves.
What is 88 level used for ?
For condition names.
What is level 66 used for ?
For RENAMES clause.
What does the IS NUMERIC clause establish ?
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 - .
How do you define a table/array in COBOL?
ARRAYS.
05 ARRAY1 PIC X(9) OCCURS 10 TIMES.
05 ARRAY2 PIC X(6) OCCURS 20 TIMES INDEXED BY WS-INDEX.
Can the OCCURS clause be at the 01 level?
No.
What is the difference between index and subscript? - GS
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.
What is the difference between SEARCH and SEARCH ALL? - GS
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.
What should be the sorting order for SEARCH ALL? - GS
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).
What is binary search?
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.
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?
Must use compiler option SSRANGE if you want array bounds checking. Default is NOSSRANGE.
How do you sort in a COBOL program? Give sort file definition, sort statement syntax and meaning. - GS
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.
How do you define a sort file in JCL that runs the COBOL program?
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.
What is the difference between performing a SECTION and a PARAGRAPH? - GS
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.
What is the use of EVALUATE statement? - GS
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.
What are the different forms of EVALUATE statement?
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
How do you come out of an EVALUATE statement? - GS
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.
In an EVALUATE statement, can I give a complex condition on a when clause?
Yes.
What is a scope terminator? Give examples.
Scope terminator is used to mark the end of a verb e.g. EVALUATE, END-EVALUATE; IF, END-IF.
How do you do in-line PERFORM? - GS
PERFORM ...
END-PERFORM
When would you use in-line perform?
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 Para and use
PERFORM Para name rather than in-line perform.
What is the difference between CONTINUE & NEXT SENTENCE ?
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 ***
Manual testing interview question and answers
What makes a good test engineer?
A good test engineer has a 'test to break' attitude, an ability to take the point of view of the customer, a strong desire for quality, and an attention to detail. Tact and diplomacy are useful in maintaining a cooperative relationship with developers, and an ability to communicate with both technical (developers) and non-technical (customers, management) people is useful. Previous software development experience can be helpful as it provides a deeper understanding of the software development process, gives the tester an appreciation for the developers' point of view, and reduce the learning curve in automated test tool programming. Judgement skills are needed to assess high-risk areas of an application on which to focus testing efforts when time is limited.
What makes a good Software QA engineer?
The same qualities a good tester has are useful for a QA engineer. Additionally, they must be able to understand the entire software development process and how it can fit into the business approach and goals of the organization. Communication skills and the ability to understand various sides of issues are important. In organizations in the early stages of implementing QA processes, patience and diplomacy are especially needed. An ability to find problems as well as to see 'what's missing' is important for inspections and reviews.
What makes a good QA or Test manager?
A good QA, test, or QA/Test(combined) manager should:
• be familiar with the software development process
• be able to maintain enthusiasm of their team and promote a positive atmosphere, despite
• what is a somewhat 'negative' process (e.g., looking for or preventing problems)
• be able to promote teamwork to increase productivity
• be able to promote cooperation between software, test, and QA engineers
• have the diplomatic skills needed to promote improvements in QA processes
• have the ability to withstand pressures and say 'no' to other managers when quality is insufficient or QA processes are not being adhered to
• have people judgement skills for hiring and keeping skilled personnel
• be able to communicate with technical and non-technical people, engineers, managers, and customers.
• be able to run meetings and keep them focused
What's the role of documentation in QA?
Critical. (Note that documentation can be electronic, not necessarily paper.) QA practices should be documented such that they are repeatable. Specifications, designs, business rules, inspection reports, configurations, code changes, test plans, test cases, bug reports, user manuals, etc. should all be documented. There should ideally be a system for easily finding and obtaining documents and determining what documentation will have a particular piece of information. Change management for documentation should be used if possible.
What's the big deal about 'requirements'?
One of the most reliable methods of insuring problems, or failure, in a complex software project is to have poorly documented requirements specifications. Requirements are the details describing an application's externally-perceived functionality and properties. Requirements should be clear, complete, reasonably detailed, cohesive, attainable, and testable. A non-testable requirement would be, for example, 'user-friendly' (too subjective). A testable requirement would be something like 'the user must enter their previously-assigned password to access the application'. Determining and organizing requirements details in a useful and efficient way can be a difficult effort; different methods are available depending on the particular project. Many books are available that describe various approaches to this task. (See the Bookstore section's 'Software Requirements Engineering' category for books on Software Requirements.)
Care should be taken to involve ALL of a project's significant 'customers' in the requirements process. 'Customers' could be in-house personnel or out, and could include end-users, customer acceptance testers, customer contract officers, customer management, future software maintenance engineers, salespeople, etc. Anyone who could later derail the project if their expectations aren't met should be included if possible.
Organizations vary considerably in their handling of requirements specifications. Ideally, the requirements are spelled out in a document with statements such as 'The product shall.....'. 'Design' specifications should not be confused with 'requirements'; design specifications should be traceable back to the requirements.
In some organizations requirements may end up in high level project plans, functional specification documents, in design documents, or in other documents at various levels of detail. No matter what they are called, some type of documentation with detailed requirements will be needed by testers in order to properly plan and execute tests. Without such documentation, there will be no clear-cut way to determine if a software application is performing correctly.
'Agile' methods such as XP use methods requiring close interaction and cooperation between programmers and customers/end-users to iteratively develop requirements. The programmer uses 'Test first' development to first create automated unit testing code, which essentially embodies the requirements.
What steps are needed to develop and run software tests?
The following are some of the steps to consider:
• Obtain requirements, functional design, and internal design specifications and other necessary documents
• Obtain budget and schedule requirements
• Determine project-related personnel and their responsibilities, reporting requirements, required standards and processes (such as release processes, change processes, etc.)
• Identify application's higher-risk aspects, set priorities, and determine scope and limitations of tests
• Determine test approaches and methods - unit, integration, functional, system, load, usability tests, etc.
• Determine test environment requirements (hardware, software, communications, etc.)
• Determine testware requirements (record/playback tools, coverage analyzers, test tracking, problem/bug tracking, etc.)
• Determine test input data requirements
• Identify tasks, those responsible for tasks, and labor requirements
• Set schedule estimates, timelines, milestones
• Determine input equivalence classes, boundary value analyses, error classes
• Prepare test plan document and have needed reviews/approvals
• Write test cases
• Have needed reviews/inspections/approvals of test cases
• Prepare test environment and testware, obtain needed user manuals/reference documents/configuration guides/installation guides, set up test tracking processes, set up logging and archiving processes, set up or obtain test input data
• Obtain and install software releases
• Perform tests
• Evaluate and report results
• Track problems/bugs and fixes
• Retest as needed
• Maintain and update test plans, test cases, test environment, and testware through life cycle
What's a 'test plan'?
A software project test plan is a document that describes the objectives, scope, approach, and focus of a software testing effort. The process of preparing a test plan is a useful way to think through the efforts needed to validate the acceptability of a software product. The completed document will help people outside the test group understand the 'why' and 'how' of product validation. It should be thorough enough to be useful but not so thorough that no one outside the test group will read it. The following are some of the items that might be included in a test plan, depending on the particular project:
• Title
• Identification of software including version/release numbers
• Revision history of document including authors, dates, approvals
• Table of Contents
• Purpose of document, intended audience
• Objective of testing effort
• Software product overview
• Relevant related document list, such as requirements, design documents, other test plans, etc.
• Relevant standards or legal requirements
• Traceability requirements
• Relevant naming conventions and identifier conventions
• Overall software project organization and personnel/contact-info/responsibilties
• Test organization and personnel/contact-info/responsibilities
• Assumptions and dependencies
• Project risk analysis
• Testing priorities and focus
• Scope and limitations of testing
• Test outline - a decomposition of the test approach by test type, feature, functionality, process, system, module, etc. as applicable
• Outline of data input equivalence classes, boundary value analysis, error classes
• Test environment - hardware, operating systems, other required software, data configurations, interfaces to other systems
• Test environment validity analysis - differences between the test and production systems and their impact on test validity.
• Test environment setup and configuration issues
• Software migration processes
• Software CM processes
• Test data setup requirements
• Database setup requirements
• Outline of system-logging/error-logging/other capabilities, and tools such as screen capture software, that will be used to help describe and report bugs
• Discussion of any specialized software or hardware tools that will be used by testers to help track the cause or source of bugs
• Test automation - justification and overview
• Test tools to be used, including versions, patches, etc.
• Test script/test code maintenance processes and version control
• Problem tracking and resolution - tools and processes
• Project test metrics to be used
• Reporting requirements and testing deliverables
• Software entrance and exit criteria
• Initial sanity testing period and criteria
• Test suspension and restart criteria
• Personnel allocation
• Personnel pre-training needs
• Test site/location
• Outside test organizations to be utilized and their purpose, responsibilties, deliverables, contact persons, and coordination issues
• Relevant proprietary, classified, security, and licensing issues.
• Open issues
• Appendix - glossary, acronyms, etc.
(See the Bookstore section's 'Software Testing' and 'Software QA' categories for useful books with more information.)
What's a 'test case'?
• A test case is a document that describes an input, action, or event and an expected response, to determine if a feature of an application is working correctly. A test case should contain particulars such as test case identifier, test case name, objective, test conditions/setup, input data requirements, steps, and expected results.
• Note that the process of developing test cases can help find problems in the requirements or design of an application, since it requires completely thinking through the operation of the application. For this reason, it's useful to prepare test cases early in the development cycle if possible.
What should be done after a bug is found?
The bug needs to be communicated and assigned to developers that can fix it. After the problem is resolved, fixes should be re-tested, and determinations made regarding requirements for regression testing to check that fixes didn't create problems elsewhere. If a problem-tracking system is in place, it should encapsulate these processes. A variety of commercial problem-tracking/management software tools are available (see the 'Tools' section for web resources with listings of such tools). The following are items to consider in the tracking process:
• Complete information such that developers can understand the bug, get an idea of it's severity, and reproduce it if necessary.
• Bug identifier (number, ID, etc.)
• Current bug status (e.g., 'Released for Retest', 'New', etc.)
• The application name or identifier and version
• The function, module, feature, object, screen, etc. where the bug occurred
• Environment specifics, system, platform, relevant hardware specifics
• Test case name/number/identifier
• One-line bug description
• Full bug description
• Description of steps needed to reproduce the bug if not covered by a test case or if the developer doesn't have easy access to the test case/test script/test tool
• Names and/or descriptions of file/data/messages/etc. used in test
• File excerpts/error messages/log file excerpts/screen shots/test tool logs that would be helpful in finding the cause of the problem
• Severity estimate (a 5-level range such as 1-5 or 'critical'-to-'low' is common)
• Was the bug reproducible?
• Tester name
• Test date
• Bug reporting date
• Name of developer/group/organization the problem is assigned to
• Description of problem cause
• Description of fix
• Code section/file/module/class/method that was fixed
• Date of fix
• Application version that contains the fix
• Tester responsible for retest
• Retest date
• Retest results
• Regression testing requirements
• Tester responsible for regression tests
• Regression testing results
A reporting or tracking process should enable notification of appropriate personnel at various stages. For instance, testers need to know when retesting is needed, developers need to know when bugs are found and how to get the needed information, and reporting/summary capabilities are needed for managers.
What is 'configuration management'?
Configuration management covers the processes used to control, coordinate, and track: code, requirements, documentation, problems, change requests, designs, tools/compilers/libraries/patches, changes made to them, and who makes the changes. (See the 'Tools' section for web resources with listings of configuration management tools. Also see the Bookstore section's 'Configuration Management' category for useful books with more information.)
What if the software is so buggy it can't really be tested at all?
The best bet in this situation is for the testers to go through the process of reporting whatever bugs or blocking-type problems initially show up, with the focus being on critical bugs. Since this type of problem can severely affect schedules, and indicates deeper problems in the software development process (such as insufficient unit testing or insufficient integration testing, poor design, improper build or release procedures, etc.) managers should be notified, and provided with some documentation as evidence of the problem.
How can it be known when to stop testing?
This can be difficult to determine. Many modern software applications are so complex, and run in such an interdependent environment, that complete testing can never be done. Common factors in deciding when to stop are:
• Deadlines (release deadlines, testing deadlines, etc.)
• Test cases completed with certain percentage passed
• Test budget depleted
• Coverage of code/functionality/requirements reaches a specified point
• Bug rate falls below a certain level
• Beta or alpha testing period ends
What if there isn't enough time for thorough testing?
Use risk analysis to determine where testing should be focused.
Since it's rarely possible to test every possible aspect of an application, every possible combination of events, every dependency, or everything that could go wrong, risk analysis is appropriate to most software development projects. This requires judgement skills, common sense, and experience. (If warranted, formal methods are also available.) Considerations can include:
• Which functionality is most important to the project's intended purpose?
• Which functionality is most visible to the user?
• Which functionality has the largest safety impact?
• Which functionality has the largest financial impact on users?
• Which aspects of the application are most important to the customer?
• Which aspects of the application can be tested early in the development cycle?
• Which parts of the code are most complex, and thus most subject to errors?
• Which parts of the application were developed in rush or panic mode?
• Which aspects of similar/related previous projects caused problems?
• Which aspects of similar/related previous projects had large maintenance expenses?
• Which parts of the requirements and design are unclear or poorly thought out?
• What do the developers think are the highest-risk aspects of the application?
• What kinds of problems would cause the worst publicity?
• What kinds of problems would cause the most customer service complaints?
• What kinds of tests could easily cover multiple functionalities?
• Which tests will have the best high-risk-coverage to time-required ratio?
What if the project isn't big enough to justify extensive testing?
Consider the impact of project errors, not the size of the project. However, if extensive testing is still not justified, risk analysis is again needed and the same considerations as described previously in 'What if there isn't enough time for thorough testing?' apply. The tester might then do ad hoc testing, or write up a limited test plan based on the risk analysis.
What can be done if requirements are changing continuously?
A common problem and a major headache.
• Work with the project's stakeholders early on to understand how requirements might change so that alternate test plans and strategies can be worked out in advance, if possible.
• It's helpful if the application's initial design allows for some adaptability so that later changes do not require redoing the application from scratch.
• If the code is well-commented and well-documented this makes changes easier for the developers.
• Use rapid prototyping whenever possible to help customers feel sure of their requirements and minimize changes.
• The project's initial schedule should allow for some extra time commensurate with the possibility of changes.
• Try to move new requirements to a 'Phase 2' version of an application, while using the original requirements for the 'Phase 1' version.
• Negotiate to allow only easily-implemented new requirements into the project, while moving more difficult new requirements into future versions of the application.
• Be sure that customers and management understand the scheduling impacts, inherent risks, and costs of significant requirements changes. Then let management or the customers (not the developers or testers) decide if the changes are warranted - after all, that's their job.
• Balance the effort put into setting up automated testing with the expected effort required to re-do them to deal with changes.
• Try to design some flexibility into automated test scripts.
• Focus initial automated testing on application aspects that are most likely to remain unchanged.
• Devote appropriate effort to risk analysis of changes to minimize regression testing needs.
• Design some flexibility into test cases (this is not easily done; the best bet might be to minimize the detail in the test cases, or set up only higher-level generic-type test plans)
• Focus less on detailed test plans and test cases and more on ad hoc testing (with an understanding of the added risk that this entails).
What if the application has functionality that wasn't in the requirements?
It may take serious effort to determine if an application has significant unexpected or hidden functionality, and it would indicate deeper problems in the software development process. If the functionality isn't necessary to the purpose of the application, it should be removed, as it may have unknown impacts or dependencies that were not taken into account by the designer or the customer. If not removed, design information will be needed to determine added testing needs or regression testing needs. Management should be made aware of any significant added risks as a result of the unexpected functionality. If the functionality only effects areas such as minor improvements in the user interface, for example, it may not be a significant risk.
How can Software QA processes be implemented without stifling productivity?
By implementing QA processes slowly over time, using consensus to reach agreement on processes, and adjusting and experimenting as an organization grows and matures, productivity will be improved instead of stifled. Problem prevention will lessen the need for problem detection, panics and burn-out will decrease, and there will be improved focus and less wasted effort. At the same time, attempts should be made to keep processes simple and efficient, minimize paperwork, promote computer-based processes and automated tracking and reporting, minimize time required in meetings, and promote training as part of the QA process. However, no one - especially talented technical types - likes rules or bureacracy, and in the short run things may slow down a bit. A typical scenario would be that more days of planning and development will be needed, but less time will be required for late-night bug-fixing and calming of irate customers.
What if an organization is growing so fast that fixed QA processes are impossible?
This is a common problem in the software industry, especially in new technology areas. There is no easy solution in this situation, other than:
• Hire good people
• Management should 'ruthlessly prioritize' quality issues and maintain focus on the customer
• Everyone in the organization should be clear on what 'quality' means to the customer
How does a client/server environment affect testing?
Client/server applications can be quite complex due to the multiple dependencies among clients, data communications, hardware, and servers. Thus testing requirements can be extensive. When time is limited (as it usually is) the focus should be on integration and system testing. Additionally, load/stress/performance testing may be useful in determining client/server application limitations and capabilities. There are commercial tools to assist with such testing. (See the 'Tools' section for web resources with listings that include these kinds of test tools.)
How can World Wide Web sites be tested?
Web sites are essentially client/server applications - with web servers and 'browser' clients. Consideration should be given to the interactions between html pages, TCP/IP communications, Internet connections, firewalls, applications that run in web pages (such as applets, javascript, plug-in applications), and applications that run on the server side (such as cgi scripts, database interfaces, logging applications, dynamic page generators, asp, etc.). Additionally, there are a wide variety of servers and browsers, various versions of each, small but sometimes significant differences between them, variations in connection speeds, rapidly changing technologies, and multiple standards and protocols. The end result is that testing for web sites can become a major ongoing effort. Other considerations might include:
• What are the expected loads on the server (e.g., number of hits per unit time?), and what kind of performance is required under such loads (such as web server response time, database query response times). What kinds of tools will be needed for performance testing (such as web load testing tools, other tools already in house that can be adapted, web robot downloading tools, etc.)?
• Who is the target audience? What kind of browsers will they be using? What kind of connection speeds will they by using? Are they intra- organization (thus with likely high connection speeds and similar browsers) or Internet-wide (thus with a wide variety of connection speeds and browser types)?
• What kind of performance is expected on the client side (e.g., how fast should pages appear, how fast should animations, applets, etc. load and run)?
• Will down time for server and content maintenance/upgrades be allowed? how much?
• What kinds of security (firewalls, encryptions, passwords, etc.) will be required and what is it expected to do? How can it be tested?
• How reliable are the site's Internet connections required to be? And how does that affect backup system or redundant connection requirements and testing?
• What processes will be required to manage updates to the web site's content, and what are the requirements for maintaining, tracking, and controlling page content, graphics, links, etc.?
• Which HTML specification will be adhered to? How strictly? What variations will be allowed for targeted browsers?
• Will there be any standards or requirements for page appearance and/or graphics throughout a site or parts of a site??
• How will internal and external links be validated and updated? how often?
• Can testing be done on the production system, or will a separate test system be required? How are browser caching, variations in browser option settings, dial-up connection variabilities, and real-world internet 'traffic congestion' problems to be accounted for in testing?
• How extensive or customized are the server logging and reporting requirements; are they considered an integral part of the system and do they require testing?
• How are cgi programs, applets, javascripts, ActiveX components, etc. to be maintained, tracked, controlled, and tested?
Some sources of site security information include the Usenet newsgroup 'comp.security.announce' and links concerning web site security in the 'Other Resources' section.
Some usability guidelines to consider - these are subjective and may or may not apply to a given situation (Note: more information on usability testing issues can be found in articles about web site usability in the 'Other Resources' section):
• Pages should be 3-5 screens max unless content is tightly focused on a single topic. If larger, provide internal links within the page.
• The page layouts and design elements should be consistent throughout a site, so that it's clear to the user that they're still within a site.
• Pages should be as browser-independent as possible, or pages should be provided or generated based on the browser-type.
• All pages should have links external to the page; there should be no dead-end pages.
• The page owner, revision date, and a link to a contact person or organization should be included on each page.
Many new web site test tools have appeared in the recent years and more than 280 of them are listed in the 'Web Test Tools' section.
A good test engineer has a 'test to break' attitude, an ability to take the point of view of the customer, a strong desire for quality, and an attention to detail. Tact and diplomacy are useful in maintaining a cooperative relationship with developers, and an ability to communicate with both technical (developers) and non-technical (customers, management) people is useful. Previous software development experience can be helpful as it provides a deeper understanding of the software development process, gives the tester an appreciation for the developers' point of view, and reduce the learning curve in automated test tool programming. Judgement skills are needed to assess high-risk areas of an application on which to focus testing efforts when time is limited.
What makes a good Software QA engineer?
The same qualities a good tester has are useful for a QA engineer. Additionally, they must be able to understand the entire software development process and how it can fit into the business approach and goals of the organization. Communication skills and the ability to understand various sides of issues are important. In organizations in the early stages of implementing QA processes, patience and diplomacy are especially needed. An ability to find problems as well as to see 'what's missing' is important for inspections and reviews.
What makes a good QA or Test manager?
A good QA, test, or QA/Test(combined) manager should:
• be familiar with the software development process
• be able to maintain enthusiasm of their team and promote a positive atmosphere, despite
• what is a somewhat 'negative' process (e.g., looking for or preventing problems)
• be able to promote teamwork to increase productivity
• be able to promote cooperation between software, test, and QA engineers
• have the diplomatic skills needed to promote improvements in QA processes
• have the ability to withstand pressures and say 'no' to other managers when quality is insufficient or QA processes are not being adhered to
• have people judgement skills for hiring and keeping skilled personnel
• be able to communicate with technical and non-technical people, engineers, managers, and customers.
• be able to run meetings and keep them focused
What's the role of documentation in QA?
Critical. (Note that documentation can be electronic, not necessarily paper.) QA practices should be documented such that they are repeatable. Specifications, designs, business rules, inspection reports, configurations, code changes, test plans, test cases, bug reports, user manuals, etc. should all be documented. There should ideally be a system for easily finding and obtaining documents and determining what documentation will have a particular piece of information. Change management for documentation should be used if possible.
What's the big deal about 'requirements'?
One of the most reliable methods of insuring problems, or failure, in a complex software project is to have poorly documented requirements specifications. Requirements are the details describing an application's externally-perceived functionality and properties. Requirements should be clear, complete, reasonably detailed, cohesive, attainable, and testable. A non-testable requirement would be, for example, 'user-friendly' (too subjective). A testable requirement would be something like 'the user must enter their previously-assigned password to access the application'. Determining and organizing requirements details in a useful and efficient way can be a difficult effort; different methods are available depending on the particular project. Many books are available that describe various approaches to this task. (See the Bookstore section's 'Software Requirements Engineering' category for books on Software Requirements.)
Care should be taken to involve ALL of a project's significant 'customers' in the requirements process. 'Customers' could be in-house personnel or out, and could include end-users, customer acceptance testers, customer contract officers, customer management, future software maintenance engineers, salespeople, etc. Anyone who could later derail the project if their expectations aren't met should be included if possible.
Organizations vary considerably in their handling of requirements specifications. Ideally, the requirements are spelled out in a document with statements such as 'The product shall.....'. 'Design' specifications should not be confused with 'requirements'; design specifications should be traceable back to the requirements.
In some organizations requirements may end up in high level project plans, functional specification documents, in design documents, or in other documents at various levels of detail. No matter what they are called, some type of documentation with detailed requirements will be needed by testers in order to properly plan and execute tests. Without such documentation, there will be no clear-cut way to determine if a software application is performing correctly.
'Agile' methods such as XP use methods requiring close interaction and cooperation between programmers and customers/end-users to iteratively develop requirements. The programmer uses 'Test first' development to first create automated unit testing code, which essentially embodies the requirements.
What steps are needed to develop and run software tests?
The following are some of the steps to consider:
• Obtain requirements, functional design, and internal design specifications and other necessary documents
• Obtain budget and schedule requirements
• Determine project-related personnel and their responsibilities, reporting requirements, required standards and processes (such as release processes, change processes, etc.)
• Identify application's higher-risk aspects, set priorities, and determine scope and limitations of tests
• Determine test approaches and methods - unit, integration, functional, system, load, usability tests, etc.
• Determine test environment requirements (hardware, software, communications, etc.)
• Determine testware requirements (record/playback tools, coverage analyzers, test tracking, problem/bug tracking, etc.)
• Determine test input data requirements
• Identify tasks, those responsible for tasks, and labor requirements
• Set schedule estimates, timelines, milestones
• Determine input equivalence classes, boundary value analyses, error classes
• Prepare test plan document and have needed reviews/approvals
• Write test cases
• Have needed reviews/inspections/approvals of test cases
• Prepare test environment and testware, obtain needed user manuals/reference documents/configuration guides/installation guides, set up test tracking processes, set up logging and archiving processes, set up or obtain test input data
• Obtain and install software releases
• Perform tests
• Evaluate and report results
• Track problems/bugs and fixes
• Retest as needed
• Maintain and update test plans, test cases, test environment, and testware through life cycle
What's a 'test plan'?
A software project test plan is a document that describes the objectives, scope, approach, and focus of a software testing effort. The process of preparing a test plan is a useful way to think through the efforts needed to validate the acceptability of a software product. The completed document will help people outside the test group understand the 'why' and 'how' of product validation. It should be thorough enough to be useful but not so thorough that no one outside the test group will read it. The following are some of the items that might be included in a test plan, depending on the particular project:
• Title
• Identification of software including version/release numbers
• Revision history of document including authors, dates, approvals
• Table of Contents
• Purpose of document, intended audience
• Objective of testing effort
• Software product overview
• Relevant related document list, such as requirements, design documents, other test plans, etc.
• Relevant standards or legal requirements
• Traceability requirements
• Relevant naming conventions and identifier conventions
• Overall software project organization and personnel/contact-info/responsibilties
• Test organization and personnel/contact-info/responsibilities
• Assumptions and dependencies
• Project risk analysis
• Testing priorities and focus
• Scope and limitations of testing
• Test outline - a decomposition of the test approach by test type, feature, functionality, process, system, module, etc. as applicable
• Outline of data input equivalence classes, boundary value analysis, error classes
• Test environment - hardware, operating systems, other required software, data configurations, interfaces to other systems
• Test environment validity analysis - differences between the test and production systems and their impact on test validity.
• Test environment setup and configuration issues
• Software migration processes
• Software CM processes
• Test data setup requirements
• Database setup requirements
• Outline of system-logging/error-logging/other capabilities, and tools such as screen capture software, that will be used to help describe and report bugs
• Discussion of any specialized software or hardware tools that will be used by testers to help track the cause or source of bugs
• Test automation - justification and overview
• Test tools to be used, including versions, patches, etc.
• Test script/test code maintenance processes and version control
• Problem tracking and resolution - tools and processes
• Project test metrics to be used
• Reporting requirements and testing deliverables
• Software entrance and exit criteria
• Initial sanity testing period and criteria
• Test suspension and restart criteria
• Personnel allocation
• Personnel pre-training needs
• Test site/location
• Outside test organizations to be utilized and their purpose, responsibilties, deliverables, contact persons, and coordination issues
• Relevant proprietary, classified, security, and licensing issues.
• Open issues
• Appendix - glossary, acronyms, etc.
(See the Bookstore section's 'Software Testing' and 'Software QA' categories for useful books with more information.)
What's a 'test case'?
• A test case is a document that describes an input, action, or event and an expected response, to determine if a feature of an application is working correctly. A test case should contain particulars such as test case identifier, test case name, objective, test conditions/setup, input data requirements, steps, and expected results.
• Note that the process of developing test cases can help find problems in the requirements or design of an application, since it requires completely thinking through the operation of the application. For this reason, it's useful to prepare test cases early in the development cycle if possible.
What should be done after a bug is found?
The bug needs to be communicated and assigned to developers that can fix it. After the problem is resolved, fixes should be re-tested, and determinations made regarding requirements for regression testing to check that fixes didn't create problems elsewhere. If a problem-tracking system is in place, it should encapsulate these processes. A variety of commercial problem-tracking/management software tools are available (see the 'Tools' section for web resources with listings of such tools). The following are items to consider in the tracking process:
• Complete information such that developers can understand the bug, get an idea of it's severity, and reproduce it if necessary.
• Bug identifier (number, ID, etc.)
• Current bug status (e.g., 'Released for Retest', 'New', etc.)
• The application name or identifier and version
• The function, module, feature, object, screen, etc. where the bug occurred
• Environment specifics, system, platform, relevant hardware specifics
• Test case name/number/identifier
• One-line bug description
• Full bug description
• Description of steps needed to reproduce the bug if not covered by a test case or if the developer doesn't have easy access to the test case/test script/test tool
• Names and/or descriptions of file/data/messages/etc. used in test
• File excerpts/error messages/log file excerpts/screen shots/test tool logs that would be helpful in finding the cause of the problem
• Severity estimate (a 5-level range such as 1-5 or 'critical'-to-'low' is common)
• Was the bug reproducible?
• Tester name
• Test date
• Bug reporting date
• Name of developer/group/organization the problem is assigned to
• Description of problem cause
• Description of fix
• Code section/file/module/class/method that was fixed
• Date of fix
• Application version that contains the fix
• Tester responsible for retest
• Retest date
• Retest results
• Regression testing requirements
• Tester responsible for regression tests
• Regression testing results
A reporting or tracking process should enable notification of appropriate personnel at various stages. For instance, testers need to know when retesting is needed, developers need to know when bugs are found and how to get the needed information, and reporting/summary capabilities are needed for managers.
What is 'configuration management'?
Configuration management covers the processes used to control, coordinate, and track: code, requirements, documentation, problems, change requests, designs, tools/compilers/libraries/patches, changes made to them, and who makes the changes. (See the 'Tools' section for web resources with listings of configuration management tools. Also see the Bookstore section's 'Configuration Management' category for useful books with more information.)
What if the software is so buggy it can't really be tested at all?
The best bet in this situation is for the testers to go through the process of reporting whatever bugs or blocking-type problems initially show up, with the focus being on critical bugs. Since this type of problem can severely affect schedules, and indicates deeper problems in the software development process (such as insufficient unit testing or insufficient integration testing, poor design, improper build or release procedures, etc.) managers should be notified, and provided with some documentation as evidence of the problem.
How can it be known when to stop testing?
This can be difficult to determine. Many modern software applications are so complex, and run in such an interdependent environment, that complete testing can never be done. Common factors in deciding when to stop are:
• Deadlines (release deadlines, testing deadlines, etc.)
• Test cases completed with certain percentage passed
• Test budget depleted
• Coverage of code/functionality/requirements reaches a specified point
• Bug rate falls below a certain level
• Beta or alpha testing period ends
What if there isn't enough time for thorough testing?
Use risk analysis to determine where testing should be focused.
Since it's rarely possible to test every possible aspect of an application, every possible combination of events, every dependency, or everything that could go wrong, risk analysis is appropriate to most software development projects. This requires judgement skills, common sense, and experience. (If warranted, formal methods are also available.) Considerations can include:
• Which functionality is most important to the project's intended purpose?
• Which functionality is most visible to the user?
• Which functionality has the largest safety impact?
• Which functionality has the largest financial impact on users?
• Which aspects of the application are most important to the customer?
• Which aspects of the application can be tested early in the development cycle?
• Which parts of the code are most complex, and thus most subject to errors?
• Which parts of the application were developed in rush or panic mode?
• Which aspects of similar/related previous projects caused problems?
• Which aspects of similar/related previous projects had large maintenance expenses?
• Which parts of the requirements and design are unclear or poorly thought out?
• What do the developers think are the highest-risk aspects of the application?
• What kinds of problems would cause the worst publicity?
• What kinds of problems would cause the most customer service complaints?
• What kinds of tests could easily cover multiple functionalities?
• Which tests will have the best high-risk-coverage to time-required ratio?
What if the project isn't big enough to justify extensive testing?
Consider the impact of project errors, not the size of the project. However, if extensive testing is still not justified, risk analysis is again needed and the same considerations as described previously in 'What if there isn't enough time for thorough testing?' apply. The tester might then do ad hoc testing, or write up a limited test plan based on the risk analysis.
What can be done if requirements are changing continuously?
A common problem and a major headache.
• Work with the project's stakeholders early on to understand how requirements might change so that alternate test plans and strategies can be worked out in advance, if possible.
• It's helpful if the application's initial design allows for some adaptability so that later changes do not require redoing the application from scratch.
• If the code is well-commented and well-documented this makes changes easier for the developers.
• Use rapid prototyping whenever possible to help customers feel sure of their requirements and minimize changes.
• The project's initial schedule should allow for some extra time commensurate with the possibility of changes.
• Try to move new requirements to a 'Phase 2' version of an application, while using the original requirements for the 'Phase 1' version.
• Negotiate to allow only easily-implemented new requirements into the project, while moving more difficult new requirements into future versions of the application.
• Be sure that customers and management understand the scheduling impacts, inherent risks, and costs of significant requirements changes. Then let management or the customers (not the developers or testers) decide if the changes are warranted - after all, that's their job.
• Balance the effort put into setting up automated testing with the expected effort required to re-do them to deal with changes.
• Try to design some flexibility into automated test scripts.
• Focus initial automated testing on application aspects that are most likely to remain unchanged.
• Devote appropriate effort to risk analysis of changes to minimize regression testing needs.
• Design some flexibility into test cases (this is not easily done; the best bet might be to minimize the detail in the test cases, or set up only higher-level generic-type test plans)
• Focus less on detailed test plans and test cases and more on ad hoc testing (with an understanding of the added risk that this entails).
What if the application has functionality that wasn't in the requirements?
It may take serious effort to determine if an application has significant unexpected or hidden functionality, and it would indicate deeper problems in the software development process. If the functionality isn't necessary to the purpose of the application, it should be removed, as it may have unknown impacts or dependencies that were not taken into account by the designer or the customer. If not removed, design information will be needed to determine added testing needs or regression testing needs. Management should be made aware of any significant added risks as a result of the unexpected functionality. If the functionality only effects areas such as minor improvements in the user interface, for example, it may not be a significant risk.
How can Software QA processes be implemented without stifling productivity?
By implementing QA processes slowly over time, using consensus to reach agreement on processes, and adjusting and experimenting as an organization grows and matures, productivity will be improved instead of stifled. Problem prevention will lessen the need for problem detection, panics and burn-out will decrease, and there will be improved focus and less wasted effort. At the same time, attempts should be made to keep processes simple and efficient, minimize paperwork, promote computer-based processes and automated tracking and reporting, minimize time required in meetings, and promote training as part of the QA process. However, no one - especially talented technical types - likes rules or bureacracy, and in the short run things may slow down a bit. A typical scenario would be that more days of planning and development will be needed, but less time will be required for late-night bug-fixing and calming of irate customers.
What if an organization is growing so fast that fixed QA processes are impossible?
This is a common problem in the software industry, especially in new technology areas. There is no easy solution in this situation, other than:
• Hire good people
• Management should 'ruthlessly prioritize' quality issues and maintain focus on the customer
• Everyone in the organization should be clear on what 'quality' means to the customer
How does a client/server environment affect testing?
Client/server applications can be quite complex due to the multiple dependencies among clients, data communications, hardware, and servers. Thus testing requirements can be extensive. When time is limited (as it usually is) the focus should be on integration and system testing. Additionally, load/stress/performance testing may be useful in determining client/server application limitations and capabilities. There are commercial tools to assist with such testing. (See the 'Tools' section for web resources with listings that include these kinds of test tools.)
How can World Wide Web sites be tested?
Web sites are essentially client/server applications - with web servers and 'browser' clients. Consideration should be given to the interactions between html pages, TCP/IP communications, Internet connections, firewalls, applications that run in web pages (such as applets, javascript, plug-in applications), and applications that run on the server side (such as cgi scripts, database interfaces, logging applications, dynamic page generators, asp, etc.). Additionally, there are a wide variety of servers and browsers, various versions of each, small but sometimes significant differences between them, variations in connection speeds, rapidly changing technologies, and multiple standards and protocols. The end result is that testing for web sites can become a major ongoing effort. Other considerations might include:
• What are the expected loads on the server (e.g., number of hits per unit time?), and what kind of performance is required under such loads (such as web server response time, database query response times). What kinds of tools will be needed for performance testing (such as web load testing tools, other tools already in house that can be adapted, web robot downloading tools, etc.)?
• Who is the target audience? What kind of browsers will they be using? What kind of connection speeds will they by using? Are they intra- organization (thus with likely high connection speeds and similar browsers) or Internet-wide (thus with a wide variety of connection speeds and browser types)?
• What kind of performance is expected on the client side (e.g., how fast should pages appear, how fast should animations, applets, etc. load and run)?
• Will down time for server and content maintenance/upgrades be allowed? how much?
• What kinds of security (firewalls, encryptions, passwords, etc.) will be required and what is it expected to do? How can it be tested?
• How reliable are the site's Internet connections required to be? And how does that affect backup system or redundant connection requirements and testing?
• What processes will be required to manage updates to the web site's content, and what are the requirements for maintaining, tracking, and controlling page content, graphics, links, etc.?
• Which HTML specification will be adhered to? How strictly? What variations will be allowed for targeted browsers?
• Will there be any standards or requirements for page appearance and/or graphics throughout a site or parts of a site??
• How will internal and external links be validated and updated? how often?
• Can testing be done on the production system, or will a separate test system be required? How are browser caching, variations in browser option settings, dial-up connection variabilities, and real-world internet 'traffic congestion' problems to be accounted for in testing?
• How extensive or customized are the server logging and reporting requirements; are they considered an integral part of the system and do they require testing?
• How are cgi programs, applets, javascripts, ActiveX components, etc. to be maintained, tracked, controlled, and tested?
Some sources of site security information include the Usenet newsgroup 'comp.security.announce' and links concerning web site security in the 'Other Resources' section.
Some usability guidelines to consider - these are subjective and may or may not apply to a given situation (Note: more information on usability testing issues can be found in articles about web site usability in the 'Other Resources' section):
• Pages should be 3-5 screens max unless content is tightly focused on a single topic. If larger, provide internal links within the page.
• The page layouts and design elements should be consistent throughout a site, so that it's clear to the user that they're still within a site.
• Pages should be as browser-independent as possible, or pages should be provided or generated based on the browser-type.
• All pages should have links external to the page; there should be no dead-end pages.
• The page owner, revision date, and a link to a contact person or organization should be included on each page.
Many new web site test tools have appeared in the recent years and more than 280 of them are listed in the 'Web Test Tools' section.
Dot net framework interview question and answers
When do you use virutal keyword?.
When we need to override a method of the base class in the sub class, then we give the virtual keyword in the base class method. This makes the method in the base class to be overridable. Methods, properties, and indexers can be virtual, which means that their implementation can be overridden in derived classes.
What are class access modifiers ?
Access modifiers are keywords used to specify the declared accessibility of a member or a type. This section introduces the four access modifiers:
· Public - Access is not restricted.
· Protected - Access is limited to the containing class or types derived from the containing class.
· Internal - Access is limited to the current assembly.
· Protected inertnal - Access is limited to the current assembly or types derived · from the containing class.
· Private - Access is limited to the containing type.
What Is Boxing And Unboxing?
Boxing :- Boxing is an implicit conversion of a value type to the type object type
Eg:-
Consider the following declaration of a value-type variable:
int i = 123;
object o = (object) i;
Boxing Conversion
UnBoxing :- Unboxing is an explicit conversion from the type object to a value type
Eg:
int i = 123; // A value type
object box = i; // Boxing
int j = (int)box; // Unboxing
What is Value type and refernce type in .Net?.
Value Type : A variable of a value type always contains a value of that type. The assignment to a variable of a value type creates a copy of the assigned value, while the assignment to a variable of a reference type creates a copy of the reference but not of the referenced object.
The value types consist of two main categories:
* Stuct Type
* Enumeration Type
Reference Type :Variables of reference types, referred to as objects, store references to the actual data. This section introduces the following keywords used to declare reference types:
* Class
* Interface
* Delegate
This section also introduces the following built-in reference types:
* object
* string
What is the difference between structures and enumeration?.
Unlike classes, structs are value types and do not require heap allocation. A variable of a struct type directly contains the data of the struct, whereas a variable of a class type contains a reference to the data. They are derived from System.ValueType class.
Enum->An enum type is a distinct type that declares a set of named constants.They are strongly typed constants. They are unique types that allow to declare symbolic names to integral values. Enums are value types, which means they contain their own value, can't inherit or be inherited from and assignment copies the value of one enum to another.
public enum Grade
{
A,
B,
C
}
What is namespaces?.
Namespace is a logical naming scheme for group related types.Some class types that logically belong together they can be put into a common namespace. They prevent namespace collisions and they provide scoping. They are imported as "using" in C# or "Imports" in Visual Basic. It seems as if these directives specify a particular assembly, but they don't. A namespace can span multiple assemblies, and an assembly can define multiple namespaces. When the compiler needs the definition for a class type, it tracks through each of the different imported namespaces to the type name and searches each referenced assembly until it is found.
Namespaces can be nested. This is very similar to packages in Java as far as scoping is concerned.
How do you create shared assemblies?.
Just look through the definition of Assemblies..
* An Assembly is a logical unit of code
* Assembly physically exist as DLLs or EXEs
* One assembly can contain one or more files
* The constituent files can include any file types like image files, text files etc. along with DLLs or EXEs
* When you compile your source code by default the exe/dll generated is actually an assembly
* Unless your code is bundled as assembly it can not be used in any other application
* When you talk about version of a component you are actually talking about version of the assembly to which the component belongs.
* Every assembly file contains information about itself. This information is called as Assembly Manifest.
Following steps are involved in creating shared assemblies :
* Create your DLL/EXE source code
* Generate unique assembly name using SN utility
* Sign your DLL/EXE with the private key by modifying AssemblyInfo file
* Compile your DLL/EXE
* Place the resultant DLL/EXE in global assembly cache using AL utility
What is global assembly cache?
Each computer where the common language runtime is installed has a machine-wide code cache called the global assembly cache. The global assembly cache stores assemblies specifically designated to be shared by several applications on the computer. There are several ways to deploy an assembly into the global assembly cache: · Use an installer designed to work with the global assembly cache. This is the preferred option for installing assemblies into the global assembly cache. Use a developer tool called the Global Assembly Cache tool (Gacutil.exe), provided by the .NET Framework SDK.
· Use Windows Explorer to drag assemblies into the cache.
What is MSIL?
When compiling to managed code, the compiler translates your source code into Microsoft intermediate language (MSIL), which is a CPU-independent set of instructions that can be efficiently converted to native code. MSIL includes instructions for loading, storing, initializing, and calling methods on objects, as well as instructions for arithmetic and logical operations, control flow, direct memory access, exception handling, and other operations. Before code can be run, MSIL must be converted to CPU-specific code, usually by a just-in-time (JIT) compiler. Because the common language runtime supplies one or more JIT compilers for each computer architecture it supports, the same set of MSIL can be JIT-compiled and run on any supported architecture.
When a compiler produces MSIL, it also produces metadata. Metadata describes the types in your code, including the definition of each type, the signatures of each type's members, the members that your code references, and other data that the runtime uses at execution time. The MSIL and metadata are contained in a portable executable (PE) file that is based on and extends the published Microsoft PE and common object file format (COFF) used historically for executable content. This file format, which accommodates MSIL or native code as well as metadata, enables the operating system to recognize common language runtime images. The presence of metadata in the file along with the MSIL enables your code to describe itself, which means that there is no need for type libraries or Interface Definition Language (IDL). The runtime locates and extracts the metadata from the file as needed during execution.
What is Jit compilers?.how many are available in clr?
Just-In-Time compiler- it converts the language that you write in .Net into machine language that a computer can understand. there are tqo types of JITs one is memory optimized & other is performace optimized.
What is tracing?Where it used.Explain few methods available
Tracing refers to collecting information about the application while it is running. You use tracing information to troubleshoot an application.
Tracing allows us to observe and correct programming errors. Tracing enables you to record information in various log files about the errors that might occur at run time. You can analyze these log files to find the cause of the errors.
In .NET we have objects called Trace Listeners. A listener is an object that receives the trace output and outputs it somewhere; that somewhere could be a window in your development environment, a file on your hard drive, a Windows Event log, a SQL Server or Oracle database, or any other customized data store.
The System.Diagnostics namespace provides the interfaces, classes, enumerations and structures that are used for tracing The System.Diagnostics namespace provides two classes named Trace and Debug that are used for writing errors and application execution information in logs.
All Trace Listeners have the following functions. Functionality of these functions is same except that the target media for the tracing output is determined by the Trace Listener.
Method Name Result Fail Outputs the specified text with the Call Stack.
Write Outputs the specified text.
WriteLine Outputs the specified text and a carriage return.
Flush Flushes the output buffer to the target media.
Close Closes the output stream in order to not receive the tracing/debugging output.
When we need to override a method of the base class in the sub class, then we give the virtual keyword in the base class method. This makes the method in the base class to be overridable. Methods, properties, and indexers can be virtual, which means that their implementation can be overridden in derived classes.
What are class access modifiers ?
Access modifiers are keywords used to specify the declared accessibility of a member or a type. This section introduces the four access modifiers:
· Public - Access is not restricted.
· Protected - Access is limited to the containing class or types derived from the containing class.
· Internal - Access is limited to the current assembly.
· Protected inertnal - Access is limited to the current assembly or types derived · from the containing class.
· Private - Access is limited to the containing type.
What Is Boxing And Unboxing?
Boxing :- Boxing is an implicit conversion of a value type to the type object type
Eg:-
Consider the following declaration of a value-type variable:
int i = 123;
object o = (object) i;
Boxing Conversion
UnBoxing :- Unboxing is an explicit conversion from the type object to a value type
Eg:
int i = 123; // A value type
object box = i; // Boxing
int j = (int)box; // Unboxing
What is Value type and refernce type in .Net?.
Value Type : A variable of a value type always contains a value of that type. The assignment to a variable of a value type creates a copy of the assigned value, while the assignment to a variable of a reference type creates a copy of the reference but not of the referenced object.
The value types consist of two main categories:
* Stuct Type
* Enumeration Type
Reference Type :Variables of reference types, referred to as objects, store references to the actual data. This section introduces the following keywords used to declare reference types:
* Class
* Interface
* Delegate
This section also introduces the following built-in reference types:
* object
* string
What is the difference between structures and enumeration?.
Unlike classes, structs are value types and do not require heap allocation. A variable of a struct type directly contains the data of the struct, whereas a variable of a class type contains a reference to the data. They are derived from System.ValueType class.
Enum->An enum type is a distinct type that declares a set of named constants.They are strongly typed constants. They are unique types that allow to declare symbolic names to integral values. Enums are value types, which means they contain their own value, can't inherit or be inherited from and assignment copies the value of one enum to another.
public enum Grade
{
A,
B,
C
}
What is namespaces?.
Namespace is a logical naming scheme for group related types.Some class types that logically belong together they can be put into a common namespace. They prevent namespace collisions and they provide scoping. They are imported as "using" in C# or "Imports" in Visual Basic. It seems as if these directives specify a particular assembly, but they don't. A namespace can span multiple assemblies, and an assembly can define multiple namespaces. When the compiler needs the definition for a class type, it tracks through each of the different imported namespaces to the type name and searches each referenced assembly until it is found.
Namespaces can be nested. This is very similar to packages in Java as far as scoping is concerned.
How do you create shared assemblies?.
Just look through the definition of Assemblies..
* An Assembly is a logical unit of code
* Assembly physically exist as DLLs or EXEs
* One assembly can contain one or more files
* The constituent files can include any file types like image files, text files etc. along with DLLs or EXEs
* When you compile your source code by default the exe/dll generated is actually an assembly
* Unless your code is bundled as assembly it can not be used in any other application
* When you talk about version of a component you are actually talking about version of the assembly to which the component belongs.
* Every assembly file contains information about itself. This information is called as Assembly Manifest.
Following steps are involved in creating shared assemblies :
* Create your DLL/EXE source code
* Generate unique assembly name using SN utility
* Sign your DLL/EXE with the private key by modifying AssemblyInfo file
* Compile your DLL/EXE
* Place the resultant DLL/EXE in global assembly cache using AL utility
What is global assembly cache?
Each computer where the common language runtime is installed has a machine-wide code cache called the global assembly cache. The global assembly cache stores assemblies specifically designated to be shared by several applications on the computer. There are several ways to deploy an assembly into the global assembly cache: · Use an installer designed to work with the global assembly cache. This is the preferred option for installing assemblies into the global assembly cache. Use a developer tool called the Global Assembly Cache tool (Gacutil.exe), provided by the .NET Framework SDK.
· Use Windows Explorer to drag assemblies into the cache.
What is MSIL?
When compiling to managed code, the compiler translates your source code into Microsoft intermediate language (MSIL), which is a CPU-independent set of instructions that can be efficiently converted to native code. MSIL includes instructions for loading, storing, initializing, and calling methods on objects, as well as instructions for arithmetic and logical operations, control flow, direct memory access, exception handling, and other operations. Before code can be run, MSIL must be converted to CPU-specific code, usually by a just-in-time (JIT) compiler. Because the common language runtime supplies one or more JIT compilers for each computer architecture it supports, the same set of MSIL can be JIT-compiled and run on any supported architecture.
When a compiler produces MSIL, it also produces metadata. Metadata describes the types in your code, including the definition of each type, the signatures of each type's members, the members that your code references, and other data that the runtime uses at execution time. The MSIL and metadata are contained in a portable executable (PE) file that is based on and extends the published Microsoft PE and common object file format (COFF) used historically for executable content. This file format, which accommodates MSIL or native code as well as metadata, enables the operating system to recognize common language runtime images. The presence of metadata in the file along with the MSIL enables your code to describe itself, which means that there is no need for type libraries or Interface Definition Language (IDL). The runtime locates and extracts the metadata from the file as needed during execution.
What is Jit compilers?.how many are available in clr?
Just-In-Time compiler- it converts the language that you write in .Net into machine language that a computer can understand. there are tqo types of JITs one is memory optimized & other is performace optimized.
What is tracing?Where it used.Explain few methods available
Tracing refers to collecting information about the application while it is running. You use tracing information to troubleshoot an application.
Tracing allows us to observe and correct programming errors. Tracing enables you to record information in various log files about the errors that might occur at run time. You can analyze these log files to find the cause of the errors.
In .NET we have objects called Trace Listeners. A listener is an object that receives the trace output and outputs it somewhere; that somewhere could be a window in your development environment, a file on your hard drive, a Windows Event log, a SQL Server or Oracle database, or any other customized data store.
The System.Diagnostics namespace provides the interfaces, classes, enumerations and structures that are used for tracing The System.Diagnostics namespace provides two classes named Trace and Debug that are used for writing errors and application execution information in logs.
All Trace Listeners have the following functions. Functionality of these functions is same except that the target media for the tracing output is determined by the Trace Listener.
Method Name Result Fail Outputs the specified text with the Call Stack.
Write Outputs the specified text.
WriteLine Outputs the specified text and a carriage return.
Flush Flushes the output buffer to the target media.
Close Closes the output stream in order to not receive the tracing/debugging output.
SAP-BW interview question and answers
What are the extractor types?
Application Specific
o BW Content FI, HR, CO, SAP CRM, LO Cockpit
o Customer-Generated Extractors
LIS, FI-SL, CO-PA
Cross Application (Generic Extractors)
o DB View, InfoSet, Function Module
What are the steps involved in LO Extraction?
The steps are:
o RSA5 Select the DataSources
o LBWE Maintain DataSources and Activate Extract Structures
o LBWG Delete Setup Tables
o 0LI*BW Setup tables
o RSA3 Check extraction and the data in Setup tables
o LBWQ Check the extraction queue
o LBWF Log for LO Extract Structures
o RSA7 BW Delta Queue Monitor
How to create a connection with LIS InfoStructures?
LBW0 Connecting LIS InfoStructures to BW
What is the difference between ODS and InfoCube and MultiProvider?
ODS: Provides granular data, allows overwrite and data is in transparent tables, ideal for drilldown and RRI.
CUBE: Follows the star schema, we can only append data, ideal for primary reporting.
MultiProvider: Does not have physical data. It allows to access data from different InfoProviders (Cube, ODS, InfoObject). It is also preferred for reporting.
What are Start routines, Transfer routines and Update routines?
Start Routines: The start routine is run for each DataPackage after the data has been written to the PSA and before the transfer rules have been executed. It allows complex computations for a key figure or a characteristic. It has no return value. Its purpose is to execute preliminary calculations and to store them in global DataStructures. This structure or table can be accessed in the other routines. The entire DataPackage in the transfer structure format is used as a parameter for the routine.
Transfer / Update Routines: They are defined at the InfoObject level. It is like the Start Routine. It is independent of the DataSource. We can use this to define Global Data and Global Checks.
What is the difference between start routine and update routine, when, how and why are they called?
Start routine can be used to access InfoPackage while update routines are used while updating the Data Targets.
What is the table that is used in start routines?
Always the table structure will be the structure of an ODS or InfoCube. For example if it is an ODS then active table structure will be the table.
Explain how you used Start routines in your project?
Start routines are used for mass processing of records. In start routine all the records of DataPackage is available for processing. So we can process all these records together in start routine. In one of scenario, we wanted to apply size % to the forecast data. For example if material M1 is forecasted to say 100 in May. Then after applying size %(Small 20%, Medium 40%, Large 20%, Extra Large 20%), we wanted to have 4 records against one single record that is coming in the info package. This is achieved in start routine.
What are Return Tables?
When we want to return multiple records, instead of single value, we use the return table in the Update Routine. Example: If we have total telephone expense for a Cost Center, using a return table we can get expense per employee.
How do start routine and return table synchronize with each other?
Return table is used to return the Value following the execution of start routine
Application Specific
o BW Content FI, HR, CO, SAP CRM, LO Cockpit
o Customer-Generated Extractors
LIS, FI-SL, CO-PA
Cross Application (Generic Extractors)
o DB View, InfoSet, Function Module
What are the steps involved in LO Extraction?
The steps are:
o RSA5 Select the DataSources
o LBWE Maintain DataSources and Activate Extract Structures
o LBWG Delete Setup Tables
o 0LI*BW Setup tables
o RSA3 Check extraction and the data in Setup tables
o LBWQ Check the extraction queue
o LBWF Log for LO Extract Structures
o RSA7 BW Delta Queue Monitor
How to create a connection with LIS InfoStructures?
LBW0 Connecting LIS InfoStructures to BW
What is the difference between ODS and InfoCube and MultiProvider?
ODS: Provides granular data, allows overwrite and data is in transparent tables, ideal for drilldown and RRI.
CUBE: Follows the star schema, we can only append data, ideal for primary reporting.
MultiProvider: Does not have physical data. It allows to access data from different InfoProviders (Cube, ODS, InfoObject). It is also preferred for reporting.
What are Start routines, Transfer routines and Update routines?
Start Routines: The start routine is run for each DataPackage after the data has been written to the PSA and before the transfer rules have been executed. It allows complex computations for a key figure or a characteristic. It has no return value. Its purpose is to execute preliminary calculations and to store them in global DataStructures. This structure or table can be accessed in the other routines. The entire DataPackage in the transfer structure format is used as a parameter for the routine.
Transfer / Update Routines: They are defined at the InfoObject level. It is like the Start Routine. It is independent of the DataSource. We can use this to define Global Data and Global Checks.
What is the difference between start routine and update routine, when, how and why are they called?
Start routine can be used to access InfoPackage while update routines are used while updating the Data Targets.
What is the table that is used in start routines?
Always the table structure will be the structure of an ODS or InfoCube. For example if it is an ODS then active table structure will be the table.
Explain how you used Start routines in your project?
Start routines are used for mass processing of records. In start routine all the records of DataPackage is available for processing. So we can process all these records together in start routine. In one of scenario, we wanted to apply size % to the forecast data. For example if material M1 is forecasted to say 100 in May. Then after applying size %(Small 20%, Medium 40%, Large 20%, Extra Large 20%), we wanted to have 4 records against one single record that is coming in the info package. This is achieved in start routine.
What are Return Tables?
When we want to return multiple records, instead of single value, we use the return table in the Update Routine. Example: If we have total telephone expense for a Cost Center, using a return table we can get expense per employee.
How do start routine and return table synchronize with each other?
Return table is used to return the Value following the execution of start routine
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