CICS VSAM Transparency

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Kristopher McKinney
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1 Joe Gailey Senior IT Specialists Client Technical Specialist for CICS z/os Tools 10 th May 2013 CICS VSAM Transparency

2 AGENDA Business Issue IBM s Solution How CICS VT Works (Deep Dive) Conclusions / Questions 2

3 VSAM based applications VSAM does not easily integrate with data from DB2 and other systems VSAM is not easily accessible from other platforms Maintenance and reorg tools lack the richness of DBMS VSAM is not designed to support 24x7 mixed batch and online 3

4 Typical Reasons to migrate to DB2 Integration with new applications that already are DB2 based. Web App. Server apps Multi platform applications Ease in running ad-hoc queries (On-Demand) Built in Data Integrity Ease in integrating to visual information, charts, graphs, executive dashboards 4

5 The Project is on Hold How many programs must be altered? How much application programmer time? How many separate application systems must be opened and reviewed? 5

6 Data Migration Conventional Method Conventional migration effort from VSAM to DB2 (typically measured in Months/Years) Analysis & Design Data Migration Data Testing Reprogramming Program Testing 6

7 AGENDA Business Issue IBM s Solution How CICS VT Works (Deep Dive) Conclusions / Questions 7

8 IBM s Solution CICS VSAM Transparency for z/os v2.1 A tool which allows the migration of Data from VSAM to DB2 Without the need to rewrite the Applications!! 8

9 CICS VT capabilities Tool to migrate VSAM files to DB2 without changing applications programs Single Instance of the data is maintained!! Both CICS and Batch programs containing imbedded VSAM logic can access data in DB2 using the CICS VT interface Migrated data can be accessed via SQL by new programs Legacy programs can access migrated data via SQL Lower risk migration strategy 9

10 CICS VT capabilities Completely separate from CICS and Batch application programs Transparent access to data in DB2 100% static SQL Migrate on a VSAM file by VSAM file basis Data can be re-engineered Original data format returned to programs with imbedded VSAM logic Enhanced data available using SQL 10

11 Data Migration CICS VT vs. Conventional Method Conventional migration effort from VSAM to DB2 (typically measured in months/years) Analysis & Design Data Migration Data Testing Reprogramming Program Testing VSAM to DB2 using CICS VT (often measured in months or even weeks) Analysis & Design Data Migration Data Testing Increases with number of files / tables 11

12 AGENDA Business Issue IBM s Solution How CICS VT Works (Deep Dive) Conclusions / Questions 12

13 Deployment Summary Analysis Map Migrate Skills Required Application Programmer and DBA for migration and testing Users for Testing CICS Support for defining modules DB2 Design Skills if exits are required Test Cutover 13

14 WHAT EXACTLY IS CICS VT? Before CICS VT Application Program WRITE, REWRITE READ VSAM File #1 VSAM File #2 14

15 WHAT EXACTLY IS CICS VT? V T INSERT, UPDATE SELECT DB2 Table #1 Application Program V S A M GET, READ WRITE, REWRITE VSAM File #1 VSAM File #2 Application programs unchanged 15

16 CICS VT COMPONENTS Mapping component Establishes relationship between VSAM record layout and DB2 row Data migration component Utilities to migrate data to DB2 and re-engineer if required Run time component Intercepts imbedded VSAM APIs to VSAM data sets that have been migrated to DB2 16

17 Mapping Component Defines the relationship between the VSAM record and the DB2 row One time activity for each data set and alternate index Automated method will handle most VSAM datasets Performed by the Application Programmer and the DBA 17

18 Mapping Component VSAM ISPF Mapping Data DB2 Table Run Time Drivers COBOL Copybook Usually one to one, but can be one to many CREATE TABLE TAB_KEY DEC(5,0) 18

19 Original VSAM file where ITEM_NUMBER is the Key 01 ITEM-DET. 02 ITEM-NUMBER PIC X(6). 02 ITEM-NAME PIC X(12). 03 ITEM-COLOUR PIC X(6). 03 ITEM-WEIGHT PIC X(4). 03 ITEM-COST PIC S99999V99 COMP ITEM-REORDER-QUANTITY PIC S ITEM-SUPPLIER-CODE PIC X(3). 02 ITEM-DATE-FIRST-SHIP PIC S9(9) COMP ITEM-SHELF-LIFE PIC X(2). 02 ITEM-DESCRIPTION PIC X(35). 19

20 New DB2 Table using CICS VT Mapping CREATE TABLE VID_ITEM (ITEM_NUMBER CHAR(6),ITEM_NAME CHAR(12),ITEM_COLOUR CHAR(6),ITEM_WEIGHT CHAR(4),ITEM_COST DEC(7,2),ITEM_REORDER_NO SMALLINT,ITEM_SUPP_CODE CHAR(3),ITEM_DATE_FSHIP DATE,ITEM_SHELF_LIFE CHAR(2),ITEM_DESCRIPTION CHAR(35) ) 20

21 New DB2 Table using A Single Column Approach CREATE TABLE VID_ITEM (ITEM_KEY CHAR(6),ITEM_COLUMN VCHAR(75) ) 21

22 Redefined Field Structure - Mapping VSAM with Field B redefined Key Field A Field B Field B - 1 Field B - 2 DB2 Columns Built with Field Build Exit (FBE) Index Col-Field A Col-Field B Col Field B - 1 Col Field B -2 22

23 Or Change / Re-engineer Key Field A Prod Code Widget 1 Gizmo 5 Gangley Wrench Create Meaningful Data Use DB2 Nulls 23

24 Output from the Mapping Component Data Set Information Module (DIM) Defines the relationship between the VSAM Structure and the DB2 Table Data Set Driver Module (DDM) Contains the SQL to access the DB2 Table DB2 Data Base Request Module (DBRM) Bind input for the DB2 Package 24

25 Data migration component Three Steps to Data Migration Unload existing data from VSAM file into a flat file Convert the data to DB2 format Exits are invoked to format and validate data Load DB2 data (using DB2 Load Utility) CICS VT utilities for first two steps Additional utility provided that scans VSAM files for invalid numeric fields that are mapped to DB2 numeric column types 25

26 Run time component Application programs continue to issue VSAM API calls to files CICS VT intercepts call Using a global user exit (GLUE) in CICS Using an MVS sub-system for batch programs Translates the call to an equivalent SQL call and processes in DB2 26

27 Run time component (cont) After call has been processed by CICS VT Data and RESP codes return to CICS program or Data and return and reason codes passed back to batch program 27

28 Run time component (cont) CICS CICS Changes Required Update the CICS VT Table Add PPT entries for DIM and DDM Driver Modules if not using Autoinstall Add DB2 entries to identify the Plan and Transactions Issue VT Command to refresh CICS VT Interface No requirement to recycle the CICS region 28

29 CICS Run-Time CICS Application Program CICS VT GLUE VSAM CALL No File Migrated? Yes CICS VT Driver VSAM DB2 29

30 Run time component (cont) -- Batch Replace DD Card with a SUBSYS Card Before: //ORDERFL DD DSN=ORDER.VSAM.DATASET,DISP=SHR //ORDERFL1 DD DSN=ORDER.VSAM.AIX,DISP=SHR After: //ORDERFL DD SUBSYS=(VIDS,DB2 ssid,dim-name) //ORDERFL1 DD SUBSYS=(VIDS,DB2 ssid,dim-name) 30

31 Batch Run-Time View Program VSAM I/O VSAM Program VSAM I/O CICS VT VSAM DB2 File File File Table 31

32 Performance Efficiency CICS VT uses 100% static SQL and every DB2 call uses an index CICS VT driver modules are re-entrant Concurrent batch and online programs since data is now in DB2 Online backups from DB2 Re-engineered data provides extra business value 32

33 Performance Cost Incremental View Typical CICS VT cost small % of DB2 CICS VT Native DB2 DB2 Native VSAM VSAM VSAM DB2 cost increases with # columns / row and # tables / file 33

34 AGENDA Business Issue IBM s Solution How CICS VT Works (Deep Dive) Conclusions / Questions 34

35 Conclusions CICS VT will quickly position you to exploit DB2 You Control the DB2 re-engineering You really have migrated your VSAM data to DB2, future applications can exploit the power of Relational Data via DB2 Don t spend time recoding legacy applications, rather spend time preparing your data for future multi-platform, web-enabled applications 35

36 More information VT Use the Tools pulldown 36

37 Questions 37

VSAM Access Method or DBMS?

VSAM Access Method or DBMS? TechTalk : Access method or DBMS? 11/15/04 Access Method or DBMS? Tony Skinner Transaction Processing Consultant IBM Certified System Designer tonysk@lightyr.com Business Partner Tony Skinner Lightyear