RE: Calling a Function from RPG Program having multiple Functions

 >Not that there are APIs for dynamically resolving the procedures in a
Service Program, this is not needed as often, but it has its uses.

Just to reinforce what Jon is saying, I find it beneficial to be able to
dynamically call a service program's sub procedure when doing web services.
PGM1 receives in a request and determines what program should be called to
process the xml based on DB2 entries. PGM1 then "activates" PGM2
SUBPROCEURE1 and "hands off" the parsing of the request and the composing of
the response.  To quote a hype phrase: "This creates separation of concern",
what happened to "modular programming"? :-)

Sure one could just stick to *PGM objects, but I find myself doing more and
more *SRVPGM's with multiple modules and sub-procedures, which then
necessitates the dynamic activation of those sub-procedures.


Aaron Bartell

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Jon Paris
Sent: Tuesday, May 09, 2006 10:12 AM
To: rpg400-l@xxxxxxxxxxxx
Subject: RE: Calling a Function from RPG Program having multiple Functions

 >> You can't do it that way.

 >> You need to place your functions into a service program. 

I agree that for most cases a Service program is the way to go - after all
that is what they were designed for.

However, your basic "You can't do it ..." statement is incorrect.  I can and
have done it several times.  In fact it is not even necessary to bind the
modules - you can treat _any_ PGM object as a service program if you wish.

The basic requirement is that you have a means to call the PGM and it
responds by supplying one or more procedure pointers to its internal
procedures.  You then make subsequent calls via those procedure pointers.

We have used the technique a number of times to get the effect of a
dynamically loaded "service program" - it also allows for semi) dynamic
swapping of the "service program".  Not that there are APIs for dynamically
resolving the procedures in a Service Program, this is not needed as often,
but it has its uses.


Jon Paris
Partner400

www.Partner400.com
www.RPGWorld.com 

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