Advantage TM CA-IDMS ® User Exits and Database Procedures

1. AdvantageTM CA-IDMS® User Exits and Database Procedures Data Management and Application Development DI440SN

2. Session Abstract • This session discusses the various exits available within AdvantageTM CA-IDMS® and how they can be used to monitor, modify and enhance the functionality available within AdvantageTM CA-IDMS®. Real life examples will be given. Internal conventions are also discussed.

3. Biography • Pete Charles COGITO • I have been working with AdvantageTMCA-IDMS® for more than 25 years. Six of these were with Cullinet. In this time I have given many classes and presentations at many Cullinet , Computer Associates and IUA conferences. I work for COGITO but spend the vast majority of my time at BT.

4. Agenda • AdvantageTM CA-IDMS® ’systems programming’ • DB Exits • DC/UCF Exits • Numbered Exits • Database Procedures • Miscellaneous Exits • Internal conventions

5. CA-IDMS® ’systems programming’ • Code is an extension of the AdvantageTM CA-IDMS® systems • Can have high profile on failure • Extend or modify system functions • Add system functions • Monitor system functions • Global application functionality • Written in Assembler

6. DB Exits IDMSCLCX • CALC Exit • Linked with IDMSDBMS and IDMSUTIL • Write your own CALC routine!! • Called when ever the system is calculating a CALC target page • Failure means all CALC activities fail. So system would be unusable • Can be used for tailored segmentation of large database • Only global record exit

7. DB Exits IDMSAJNX • Archive Journal exit • Linked with IDMSUAJN • Called after each journal block is offloaded • Can be used to analyses journal records • Statistics collection, Audit trails, Security Checks • Failure not too catastrophic

8. DB Exits IDMSDBIO • Four different exits available for IDMSDBIO • IDMSDPLX , IDMSIOXT , IDMSIOX2 and IDMSJN2 • All must be linked with IDMSDBIO • All I/O related • Duplicate I/O e.g. provide a duplex journal • Substitute I/O e.g. COGITO’s DB-Image, ASG’s Fast Access

9. DB Exits IDMSDBIO • I/O Error handling • IDMSIOX2 is most comprehensive • Lots of hooks for third party software • Impact of failure depends on scope • Might only affect a single file but could affect whole CV

10. DC/UCF Exits TCKREXIT • Ticker Exit • Called at every ticker interval as defined in the SYSGEN • Linked with CV startup module • Can be used to control or monitor time related events • Impact of failure. If it abends you will get SMPC every ticker interval

11. DC/UCF Exits WAITEXIT • Called at every time CV issues an operating system wait • Linked with CV startup module • Can be used to monitor ‘idle’ time

12. DC/UCF Exits WTO Exits • WTOEXIT called when ever IDMS writes to the console • Most commonly used to submit Archive Journal and Log Offload jobs • Also to submit start up, shutdown or user jobs • WTOREXIT called when ever IDMS solicits an operate reply • Both linked with CV startup module

13. Numbered Exits • Can be linked as DC program or with RHDCUXIT • Identified by number • Can use either IBM or DC calling conventions • May be user or system mode.Some system exits must be system mode • I would ALWAYS us DC Calling conventions and system mode • Abends cause system dumps

14. Numbered Exits • 0 through 255 are system exits. Currently go up to 38 • System exits defined by CA • 256 and above are user exits • Users exits called by using #XIT macro. • All defined by #DEFXIT macro

15. Numbered Exits RHDCUXIT CSECT #DEFXIT , EXIT 00 #DEFXIT MODE=SYSTEM,CALL=DC,EP=XSON,AMODE=ANY EXIT 01 #DEFXIT , EXIT 02 #DEFXIT , EXIT 03 #DEFXIT , EXIT 04 #DEFXIT MODE=SYSTEM,CALL=DC,EP=XTASK,AMODE=ANY EXIT 05 MODE=SYSTEM or USER, CALL=DC or IBM

16. Common Numbered Exits • 00 System Startup • 14 BIND RUN UNIT and READY AREA • 23 PRE BIND RUN UNIT ( Called before Exit 14 ) • 20 Resource Limit • 30 Dead Lock victim selection

17. Database Procedures • Schema Defined • Area or Record level • Linked stand alone • Called By IDMSDBMS so an extension of the database manager • Defined in SYSGEN • Write in Assembler

18. Schema Record Syntax CALL procedure-name --- BEFore -------------------------------+ +- AFTer -----------¦ +- CONnect ----¦ +- on ERRor during -+ +- DISCONnect -¦ +- ERAse ------¦ +- FINd -------¦ +- GET --------¦ +- MODify -----¦ +- STOre ------+

19. Schema Area Syntax CALL procedure-name --- BEFore ------------------------------------+ +- AFTer -----------¦ +- function-option -+ +- on ERRor during -+ Expansion of function-option >>--- REAdy ------------------------------------------------------------------>< +- for --- EXCLUSive --- UPDate --------+ +- RETrieval -+ +- PROtected --- UPDate ------ +- RETrieval -+ +- SHAred --- UPDate --------- +- RETrieval -+ +- UPDate -------------------- +- RETrieval -----------------+ - FINish ------------------------------------------¦ +- COMmit ------------------------------------------¦ +- ROLlback ----------------------------------------+

20. Compression/Decompression • CA Provide IDMSCOMP and IDMSDCOM for compression and decompresssion • Call IDMSDCOM after GET • CALL IDMSCOMP before STORE and before MODIFY • CA recommend that both are called before FINISH. Causes them to free their storage

21. DB Procedures and Security • Encrypt sensitive data • Cancel the DML Command • Can use the #SECHECK Macro

22. DB Procedures and Restructure • Use to populate new fields using application logic • Use NUPROCS parameter for restructure • Procedure called before MODIFY i.e. after record has been restructured but before it is written back to database • Very fast. Much quicker than adding field then an application to populate.

23. Miscellaneous Exits • OPTIXIT and OPTIQXIT are used in the CICS environment • Linked with IDMSINTC • Used to dynamically route transaction to different CVs • OPTIXIT is for DML and OPRQXIT is for SQL

24. Miscellaneous Exits • IDMSSVCX SVC exit • DC exits are an extension of CA-IDMS • IDMSSVCX is an extension of the operating system • It runs in key 0 supervisor state so can over write ANY location in memory • Errors in this can bring down the operating system. Yes I have seen it happen • Used to add data into ERE must commonly for accounting/charging

25. Internal Conventions • R9 always point to the TCE for the active task • R10 always points to the IDMSCSA • R13 always points to next available word in the TCE stack • R12 Normally base register • R14 Return address • R11 very often to used to point to work area

26. Internal Conventions • #MOPT Macro used to set mode to system or user ( always use system ) • #START Macro. Most import for multitasking as it defines the MP mode required by the exit • Getting MP mode wrong can have many side effects • An example is a DB procedure that was not changed to rum mode any at R1 • Caused hundreds of thousands of waits for mode DB

27. Internal Conventions • #RTN Macro just returns • #GETSTK used get a small amount of work space from TCE stack • By default address returned in R11 • If issuing any DC calls always use RGSV option on the macro being used • Can specify R2 to R8 • R9 and R10 are fixed and should never be changed

28. Internal Conventions • R11,R12, R13 and R14 are always saved • R0,R1 and R15 are overwritten by the macro so are never saved

29. Summary A Few Words to Review • Simple but powerful tools • CV administration • CV extensions • DBA tools • Application Components • Easier then they sound • Remember they are there and check if they can help you

30. Questions & Answers

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