rexx for cics - university of floridanersp.osg.ufl.edu/~sfware/share110/s8335sfw.pdf · rexx for...

REXX for CICS"Get more CICS with REXX"

Steve Ware, UF

Session 8335, SHARE 110 February 28 (Thur.), 2008, 1:30 PM Disney's Coronado Springs Resort

Coronado Chttp://nersp.cns.ufl.edu/~sfware/share110/s8335sfw.pdf (Updated: 01-25-2008)

2Session 8335, SHARE 110, Orlando, FL, Steve Ware, UF.

Abstract

The use of the REXX language in CICS offers the opportunity to further exploit REXX and CICS by providing a powerful structured language for rapid application prototyping and development in the CICS transaction processing environment.

In this session, one of the early users of REXX for CICS will relate his experiences with emphasis on implementation, application development, security and performance.

This session is eligible for the SHARE REXX Certificate.


Disclaimer

Standard disclaimers apply. Any opinions expressed are the opinion of the author only. Any mentioned brand names, trademarks, registered trademarks, service marks, etc., are the exclusive property of their owners. No warranties are either expressed or implied, your mileage may vary, etc.


Agenda/Topics

• CICS the Tires (with REXX)

• Introduction

• Implementation

• Application Development

• Security

• Performance

• Summary and Q&A

• Appendix and Additional Information


CICS the Tires (with REXX)

• Sign-on to CICS (using our local sign-on application).


CICS the Tires (cont.)

• After entering the REXX transid, we try some REXX statements. The READ in the lower right means we're still in the REXX for CICS interpreter - the CICRXTRY exec.



• We end our REXX for CICS session with "exit".



• After entering the FLST (File LiST) transaction, we get a display of our personal files in the REXX File System (RFS). The RFS is a set of VSAM files.



• After a "cd" (change directory) to our PUBLICR, R/O (Read Only) directory, we get a different list of files.



• Context sensitive help is available via F1=HELP. Some FLST commands include COPY, DELETE, EDIT, EXEC, etc.



• After an F11=EDIT with the cursor anywhere on the line for file RXKY.EXEC, we're in the REXX for CICS editor. We could have also used the "EDIT" command in the CMD field next to the file.



• After an F8=FWD, we page forward in the file. The DOWN editor command is also available.



• After an F3=END, we end our editor session.



• After an ENTER, we're back in FLST.



• Let's take a look at a REXX for CICS Panel source file, used in the RXKY exec:



• We'll end our file list session, and then use the CLEAR function key to be able to enter other CICS transactions.



• We'll enter the locally defined "RXKY" transaction identifier, to run our RXKY.EXEC. The CICS PCT definition for TRANS(RXKY) specifies PROGRAM(CICREXD).



• Note that in addition to the RXKY.EXEC being in a PUBLICR (Public Read Only) RFS directory, and the PCT definition for TRANS(RXKY), the prefix.SCICEXEC(CICSTART) exec was modified with the following statement: 'DEFTRNID' RXKY RXKY

• The above statement associates the local transid RXKY with our RXKY.EXEC file, which we looked at earlier.

• The IBM supplied definitions include: 'DEFTRNID' REXX CICRXTRY 'DEFTRNID' EDIT CICEDIT 'DEFTRNID' FLST CICFLST



• After depressing PF7, our RXKY exec runs again, with updates to the "Panel", all in CICS pseudo-conversational mode - sweet!



• After entering "END" into our RXKY Panel, our RXKY exec runs again, but terminates with the message "RXKY ended.".



• The IBM supplied RDO GROUP(CICREXX) has the following definitions, for FILEs, PROGRAMs, and TRANSACTIONs :



• The IBM supplied RDO GROUP(CICREXX) also includes definitions for TDQUEUEs, DB2ENTRY, and DB2TRANs :



• We now return you to our regularly scheduled SHARE presentation...


Introduction

• UF CNS, University of Florida Computing & Networking Services (formerly known as NERDC), is the primary data center at the Gainesville, FL campus.

• Currently utilizing an IBM z9 BC 2096-Q02 with 16GB, running z/OS 1.7, CICS TS 3.2, DB2 7.1, RACF, JES2, etc.

• 3 LPARs - 1 internal "sysprog sandbox", 1 test "alternate", and 1 production or "primary".

• We have 12 CICS regions configured, and run ~1M prod. transactions/weekday, and ~2M on peak load days.

• 2 internal/test sandbox, 2 development/test, 4 test/QA, and 4 production CICS regions currently configured.


Introduction (cont.)

• Founded in 1853, became the University of Florida in 1905. (East Florida Seminary -> Florida Agricultural College -> University of Florida)

• UF is a member of the AAU, the Association of American Universities.

• UF is one of the five largest universities in the U.S., public or private.

• ~50K enrolled and ~250K alumni.



• We're considered a "Classic" CICS site. ("Legacy = It Works!")

• Web access to CICS is via the CICS Socket Interface, in use at our site since ~1997.

• ~60% of local CICS tasks utilize sockets.

• All locally developed CICS applications are Assembler and/or COBOL. We have ~8K CICS application load modules, and ~32 have CICS sockets API (for file/data transfer, email, web enablement, etc.).

• Several internal CICS applications written in C/C++ and REXX. Java has only been IVP tested, but with our new z9 zAAP, we're looking at exploiting Java in CICS in the future.



• Are we now considered a Nouveau CICS site?

• CICS Web Services in production since Sept. 2006: http://docweb.cns.ufl.edu/update/u0610cics/u0610cics.html

• CNS & UF Registrar Implement "MyStudentBody.com" Requirement using CICS Web Services.

• "On Friday, September 22nd, 2006, UF CNS CICS systems staff and UF Office of the University Registrar application staff implemented a new, secure (https) CICS Web service, with CICS acting as the service requester, for the MyStudentBody.com UF health requirement. The new capabilities introduced to support this initiative pave the way for implementation of encrypted Web services accessing real-time student data, making applications more accurate, serving the UF community better."



• REXX: REstructured eXtended eXecutor

• REXX was designed/created by IBM fellow Mike Cowlishaw, in 1979. In the "Design of the REXX language" article from IBM Systems Journal, VOL 23, No. 4, 1994, Mike said "...effective and easy to use, yet it is sufficiently general and powerful to fulfill the needs of many demanding professional applications".

• REXX might be described as a "scripting" programming language, somewhat similar to languages such as PERL.

• CICS: IBM Customer Information Control System

• There are several "flavors" of both REXX and CICS. The focus in this session is IBM REXX for CICS, in an IBM CICS TS 3.1 or 3.2 for z/OS environment.



• REXX for CICS was originally developed by members of the IBM OfficeVision for MVS team (IBM Westlake Programming Laboratory, Roanoke, TX).

• SHARE 80 (February 1993) Session I916 - "Research on REXX in the CICS Environment", presented by David Shriver of IBM.

• Personally worked with David Shriver and Roy Bowers, starting in late 1993, and participated in "First Customer Ship" (FCS), and successfully convinced them that "pseudo-conversational" REXX for CICS was a "really good thing" ;-).

• REXX for CICS/ESA was announced on 5 Apr 1994, IBM Announcement Letter, 294-201.



• Initial REXX for CICS install at UF was in a CICS/ESA 3.3 environment, in April 1994. Presented "REXX under CICS User Experience" session at SHARE 83 in August 1994 (Boston, MA).

• The IBM CICS TS 3.1 and 3.2 Installation Guides say: "The REXX Development System for CICS® and the REXX Runtime Facility for CICS--two program products collectively referred to as REXX for CICS--provide improved productivity for a wide range of CICS activities. REXX for CICS enables you to write and execute CICS programs in a CICS region. These programs have access to most EXEC CICS commands, the CICS CEDA and CEMT transactions, and DB2® databases through the EXEC SQL interface."



• Note that the IBM designated program product prefix for REXX for CICS is "CIC" - recall that it's "DFH" for CICS.

• The REXX in REXX for CICS is an "interpreted" (not "compiled") language, based upon REXX/370. Rumor has it that a REXX for CICS compiler was developed, but was never made available in REXX for CICS.

• Does IBM consider REXX for CICS "strategic"? (Remember that this session is only 60 minutes. ;-)

• Do you or does your company consider REXX for CICS "strategic"? If so, please let IBM know!



• A "default" CICS TS 3.1 or 3.2 install will include the 3 REXX for CICS FMIDs:

1. H0B5110: REXX/CICS Runtime.

2. H0B7110: REXX/CICS Development.

3. H0Z2110: REXX/CICS Common.



• A "default" install of CICS TS 3.1 or 3.2 will create 21 REXX for CICS SMP/E target and distribution libraries with names of a format similar to: prefix.CICS.REXX.**

• In the CICS TS 3.1 or 3.2 Information Center, search for "enabling rexx", without the quotes. The section, "Enabling REXX for CICS", from the CICS TS 3.1 or 3.2 Installation Guide, is probably the best starting point in getting REXX for CICS implemented at your site.

• Follow the "10 easy steps" to enable your CICS system to provide the facilities of REXX for CICS.


Implementation

• REXX for CICS is implemented in "10 easy steps":

1. Consider your customization needs for REXX for CICS.

2. Modify your RDO definitions to add required entries.

3. Create the RFS filepools.

4. Bind the CICSQL program to your DB2 plan.

5. Add DD statements to your CICS startup job.

6. Modify member CICSTART.

7. Format the RFS filepools.

8. Verify the installation.

9. Access the supplied softcopy documentation.

10. Review customization information (if you skipped step 1. ;-).


Application Development

• REXX for CICS application development is made easy with the familiar hierarchical RFS file system, the supplied REXX for CICS interpreter, full screen editor, and easy panel creation capabilities.

• REXX for CICS application developers can easily build and test REXX for CICS applications. Installation into CICS is fairly easy and straightforward.

• REXX for CICS applications can be stand-alone, subroutine calls from other CICS applications, and REXX for CICS applications can call existing or new CICS applications.

• Import and export facilities are supplied, to easily move code and/or data in and out of the RFS and OS datasets.


Security

• REXX for CICS can be considered a sophisticated "CECI" (CICS Enhanced Command Interpreter). REXX for CICS transactions can be controlled with transaction and/or resource security, as with any typical CICS application.

• REXX for CICS requires at least one "authorized" user. This "special" user is similar to a Unix "root" user. The AUTHUSER command is used to specify "authorized" user(s).

• For "authorized" execs, control by the AUTH parameter on DEFSCMD for CICAUTH DDNAME.

• For dynamically allocated datasets, control is by user replaceable security exit. The default supplied exit allows access to datasets with a high-level index matching the current terminal userid.


Security (cont.)

• RFS access security can be used to control access to execs and data.

• This RFS control may be at the CICS level and/or RFS level. At the CICS level, authorization may be given to specific users, providing a high level of security.

• At the RFS directory level, by default, only the owning user has access. The RFS AUTH command may be used to define a directory as public or secured. If secured, the RFS security exit is invoked to determine authorization.

• Command execution security may be used to control use of specific REXX for CICS commands or command keywords.


Performance

• Although REXX for CICS execs are "interpreted", the base IBM code is written in Assembler, and generally has good performance characteristics, IMHO.

• Local CICS CMF comparisons between the RXKY exec and a similar compiled COBOL version indicate a slight advantage with COBOL, but Assembler would probably be even better, with Java probably the clear "winner" in resource consumption ;-). Remember, "it depends", and "lies, damn lies, and statistics".


Performance (cont.)

• Design choices affect performance (what else is new!).

• Exec storage in a PDS vs RFS - If SVC 99 (dynamic allocation) is used in CICS, performance degradation may/will result. RFS datasets may be placed in CICS data tables for performance considerations.

• RFS vs EXECLOAD - Use EXECLOAD via start-up or profile execs for pre-loading common or heavily used execs.

• REXX for CICS execs vs assembled/compiled languages - use compiled code for performance critical applications or critical application segments.

• Server execs vs nested (in-stream) execs - consider server execs where appropriate.


Performance (cont.)

• A CICS ROR (REXX Owning Region?) for production REXX for CICS applications could be created to isolate possible REXX for CICS performance exposure.

• Tuning, design considerations, and changes in any or all of these components can affect performance - "let's be careful out there!"


Performance (cont.)

• Here's what Mike Cowlishaw's V2.1 REXXCPS (REXX Clauses Per Second) exec says in an internal CICS region on our test LPAR - nearly 300K REXX clauses per second:


Summary

• I really like things that work, and work well - like REXX, CICS and the mainframe (ok, Linux, too ;-).

• REXX for CICS provides added value to both REXX and CICS. I personally think that it's "more that just another CICS programming language" and "more than just another REXX implementation" - it's a comprehensive application development environment.

• REXX is portable and very useful for serious programming.

• Thanks! Have a great time for the remainder of the conference, and have a safe trip home.

• Questions? Comments? Random thoughts?


Appendix and Additional Information

• IBM CICS (Customer Information Control System): http://www.ibm.com/cics (which recently resolved to) http://www-306.ibm.com/software/htp/cics/

• IBM CICS SupportPacs: http://www-306.ibm.com/software/htp/cics/support/supportpacs/info.html

• IBM Software - IBM REXX Family: http://www-306.ibm.com/software/awdtools/rexx/

• The REXX Language Association: http://www.rexxla.org/

• SHARE REXX Project: http://www.share.org/volunteer_center/programs/applications_systems.cfm#rexx


Appendix (cont.)

• SHARE ("It's not an acronym, it's what we do.") http://www.share.org/

• SHARE CICS Project: http://www.share.org/cics


Appendix (cont.)

• The University of Florida (UF): http://www.ufl.edu/

• UF Computing & Networking Services (CNS): http://www.cns.ufl.edu/

• CICS at UF: http://cics.ufl.edu/


Presentation Information

• The Slackware Linux Project: http://www.slackware.com/

• OpenOffice.org 2.2.1 "Impress": http://www.openoffice.org/ (File -> Export as PDF) (Used SHARE PowerPoint template.)

• IBM (Lenovo) ThinkPad T40 2379-D5U: http://www.lenovo.com/think/us/en/

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