RE: Only one instance of program.

Hi,

The program that generates the number is a CL program that uses a
combination of Julian date, time and some alphabets to generate a
alphanumeric combination.

I guess as you have suggested the best idea will be to have a lock on some
AS400 object as soon the CL program is called and place a lock on the AS400
object. As soon as I am finished with generating the number release the
lock. If the program is called simultaneously by some other application it
will wait till the lock gets released. So there will be a time gap and we
can ensure that the combination generated is unique.

Thanks for the suggestion.

Regards,
Venky

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of HauserSSS
Sent: Thursday, November 10, 2005 11:45 AM
To: RPG programming on the AS400 / iSeries
Subject: AW: Only one instance of program.

Hi,

do you use access to a file to generate the number?
If yes, is the file only used in this program?
If yes, you can allocacte the file at the beginning of the program, before
opening it.
And deallocate it at the end of the program.

We solved such problems with 2 small CL-Programs.
In the first program we simply try to allocate a data area for exclusive
access.
In the second program we deallocate the data area.

In the program (that only can run once), we first send a scope message
(QMHSNDSM) to make sure that the "END"-program will be executed at normal or
abnormal program end.
After we call the allocate program. We loop around this call until the
program will not fail anymore.

Here an example (sorry it's old RPGIII):
IP$SCOP     IDS
I I            '*CSE'                    1  10 P$ART
I I            'LL0400CE  *LIBL'        11  30 P$QPGM
I                                       31  32 P$DATA
I                                    B  33  360P$SCDT
I                                       37  40 P$MKEY
I                                       41  50 P$ERR
 *---------------------------------------------------------
C                     Z-ADD1         P$SCDT
C                     CALL 'QMHSNDSM'
C                     PARM           P$ART
C                     PARM           P$QPGM
C                     PARM *BLANKS   P$DATA
C                     PARM           P$SCDT
C                     PARM *BLANKS   P$MKEY
C                     PARM *BLANKS   P$ERR
 *
 * ALLOCATE DATA AREA FOR UNIQUE ACCESS
C           *IN99     DOUEQ*OFF
C                     CALL 'LL0400CA'             99
C                     ENDDO

Birgitta
-----Ursprungliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]Im Auftrag von Venkateshwar
Gesendet: Mittwoch, 9. November 2005 12:37
An: rpg400-l@xxxxxxxxxxxx
Betreff: Only one instance of program.



Hi,



Is there anyway by which I can ensure that only one instance of a program is
running? This program generates a number and there is chance that it can be
called by 2 programs to generate number and there is a chance both can get
same number.



Regards,

Venky.





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