Re: Activation Groups for Beginners (revisited)

Richard,

Regarding the discussion on activation groups and overrides...

You might find my article (and chapter from my book) "So You Think You
Understand File Overrides" helpful. It appeared in the July 2001 issue
of iSeries NEWS. It gives you the real skinny on how overrides are
applied.

If you're a professional member of the iSeriesNetwork, you can read the
article online at:


http://www.iseriesnetwork.com/resources/artarchive/index.cfm?fuseaction=viewarticle&CO_ContentID=10447&channel=art

Some of the online figures may be difficult to read, unfortunately.

Gary Guthrie
Senior Technical Editor, iSeries NEWS


Richard B Baird wrote:
>
> Buck,
>
> I finally found the time to go back through the AGs for beginners thread.
> Again, thanks for all your (and everyone else's) help.
>
> I came across the following example you gave and have questions INLINE...
>
> ---Buck said (a long time ago):---------
> >My suggestion is to use ACTGRP('QILE')
> >My reasoning is that there's no reason to subdivide such an application
> into
> >AGs because there's no benefit.  Has anyone had bad experiences with a
> >similar arrangement?  I haven't.  Here's an example:
>
> >CLP AG(*DAG)
> >  OVRDBF MASTER MBR(MAR)
> >  CALL PRINT, AG('QILE')
> >    System activates program
> >      Allocate/init static storage
> >      Complete binding to service programs
> >    Open MASTER, mbr(JAN)
>
> why was member JAN opened?  the override was to MAR.
> if the override was SHARE(*YES), would AG QILE use it then?
>
> >    ...
> >    Close MASTER
> >    SETON LR - program still activated in AG('QILE')
> >  CALL OPMUPDATE, AG('QILE')
> >    Open MASTER, mbr(JAN)
>
> OPM override still active to member MAR.  AG QILE still active.
> still not using override?
>
> >    ...
> >    Close MASTER
> >    SETON LR
> >  CALL PRINT, AG('QILE')
> >    Program is still activated!
> >    Open MASTER, mbr(JAN)
>
> same thing?
>
> >    ...
> >    Close MASTER
> >    SETON LR - program still activated in AG('QILE')
> >ENDPGM
> >
> >/* AG('QILE') is still in existence for this job */
> >/* OVRDBF to MASTER is gone, since the CLP issuing it ended */
> >
> >CLP AG(*DAG)
> >  OVRDBF MASTER MBR(SAV)
> >  CALL PRINT, AG('QILE')
> >    Program is still activated!
> >    Open MASTER, mbr(JAN)
> >    ...
> >    Close MASTER
> >    SETON LR - program still activated in AG('QILE')
> >ENDPGM
> >
> >/* AG('QILE') is still in existence for this job */
> >/* OVRDBF to MASTER is gone, since the CLP issuing it ended */
> >
> >Job terminates, AG('QILE') for this job terminates too.
> >The override from the OPM carries into AG('QILE') so there's no real
> concern
> >on that score.  The print program doesn't use static storage so that's no
> >concern either.
>
> I guess my question is, if you mix OPM with DAG and ILE with NAG, your OPM
> overrides don't effect any ILE NAGs?  what if you used SHARE(*YES) on the
> override?
>
> another example you gave KIND OF indicates the answer...:
>
> -------Buck said in another post-------
> >Scenario 2:
> >GLCL - AG(DAG)
> >  CHTACCTS (DAG)
> >    VENMAINT (MYCOMPANY)
> >APCL - AG(DAG)
> >  VENMAINT (MYCOMPANY)
> >
> >VENDOR is opened by an OPM program and SHARE(*YES) specified, so the
> OVRDBF
> >percolates through to AG('MYCOMPANY')  The original OPM behaviour and
> >performance is maintained.  Each time VENMAINT opens VENDOR, it'll be a
> >shared open.  The expectation is that the OPM programs are already doing
> >implicit sharing among themselves, just at the job level instead of the AG
> >level.
>
> If this is true (OPM DAG file overrides do not effect subsequently called
> ILE NAG file opens), this would worry me, when converting OPM to ILE one
> program at a time.  overrides that used to work in OPM now don't work if a
> single program that used to use the override was created with a named AG.
>
> Am I missing something?