DL/I Database Access
Database Language/I (DL/1) is a database access method of Information Management System (IMS), which is another popular IBM DB/DC control system similar to CICS. The DL/1 database is a hierarchical database constructed for the DL/I database access method.
DL/I Database Access by CICS
CICS provides an interface to DL/I, independent of IMS in addition to the file control functions performed by the File Control Program. Therefore, this DL/I interface all DL/I services can be used under CICS.
As shown in the above figure, within a CICS region, there is a built-in interface to DL/1. This DL/1 interface communicates with the PL/I database method software included in CICS. In this way, CICS can have a direct control over the DL/1 database, independent of IMS, which means that CICS region itself can manage the DL/1 accesses.
CICS application programs can issue a set of commands for DL/1 services. The DL/1 interface interprets the service requests by the, application program and pass control to the DL/1 access method modules, which actually access the DL/1 database.
Where function is a DL/1 service and options are the options of the DL/1 service. The CICS application programs issue the DL/1 commands as and when they are required. The CICS command translator translates these DL/1 commands into the proper COBOL statements similar to the CICS commands. Since CICS has direct control over DL/1, in order to utilize DL/1 services, CICS control tables must be defined for the directory of DL/1 Database Descriptions (DBD) and Program Specification Blocks (PSB) through the control table definition macros DFHDLDBD and DFHDLPSB. DBD defines the physical structure of the DL/1 database while the PSB defines the database elements an application is authorized to use. Once these table entries have been defined, the CICS application programs can use the EXEC DLI commands in the program for accessing the DL/1 database.
DB/2 Database Access
DB/2 is IBM's Relational Database Management System (RDBMS) and the database access method for DB/2 is SQL (Structured Query Language). CICS provides an interface to DB/2, but DB/2 requires its own region independent of the CICS region. Therefore the way of interfacing is different from that of DL/1. The way in which CICS accesses DB2 is shown in the following figure.
D62 Database Access by CICS
Both CICS and DB/2 require its own unique regions under the OS. In order to make an interface between CICS and DB/2, DB/2 has a special facility called CICS Attachment Facility, which connects DB/2 to CICS. CICS application programs can issue a set of commands for SQL services in order to access the DB/2 database.
Where 'function' is an SQL function and 'options' is the options of the SQL service. The application programs, which contain EXEC SQL statements, must be Pre-complied using the DB/2 Pre-compiler, which translates the SQL command into COBOL statements. Although CICS translator does not reject the SQL commands as syntax error, the translation time is reduced if the program is pre-compiled first. So the process is shown in the following figure.
Development of CICS-DB2-COBOL Program
The SQL commands that can be used in a CICS application programs are SELECT, FETCH, UPDATE, DELETE and INSERT.
IBM Mainframe Related Interview Questions
|IBM Lotus Notes Interview Questions||IBM-CICS Interview Questions|
|COBOL Interview Questions||Linux Interview Questions|
|IBM-JCL Interview Questions||IBM Mainframe Interview Questions|
|IBM AIX Interview Questions||IBM WAS Administration Interview Questions|
|IBM Lotus Domino Interview Questions||IBM Integration Bus Interview Questions|
|Mainframe DB2 Interview Questions||Unix Production Support Interview Questions|
Ibm Mainframe Tutorial
Introduction To Software Development
Introduction To Ibm Mainframes
Tso And Ispf
Jes2, ]es3 And Sms
Introduction To Job Control Language (jcl)
The Job Statement
The Exec Statement
The Job And Exec Statements
The Dd Statement
Procedures And Symbolic Parameters
Generation Data Groups (gdg), Compile/link-edit And Run Jcls
Access Method Services (ams)
Additional Vsam Commands
Introduction To Rexx
Overview Of Rexx
Introduction To Cics
Exception Handling In Cics
Developing A Cics Application
Cics Programming Techniques
Basic Mapping Support (bms)
Transient Data Control
Temporary Storage Control
Interval And Task Control
Cics Application Design
Recovery And Restart
System Security And Intersystem Communication
Cics Debugging Facilities And Techniques
Bms Map Definition Macros And Copylib Members
Cics Response And Abend Codes
Data, Information And Information Processing
Introduction To Database Management Systems
Introduction To Relational Database Management Systems
Database Architecture And Data Modeling
Overview Of Db2
Structured Query Language (sql)
Data Security And Access
Db2 Application Development
Qmf And Db2i
Db2 Performance Monitoring, Utilities And Recovery/restart
Overview Of Information Management System (ims)
Introduction To Vs Cobol Ii
Overview Of Application Development In Vs Cobol Ii
Overview Of The Cobol Program
Sorting And Merging Files
Coding Cobol Programs That Run Under Cics. Ims, Db2 And Ispf
Compiling The Program
Link-editing The Program
Executing The Program
Improving Program Performance
All rights reserved © 2018 Wisdom IT Services India Pvt. Ltd
Wisdomjobs.com is one of the best job search sites in India.