Multiple parallel ABAP Proxy calls by multiple users

[adnanmaqbool]

Dear Experts

I have a situation where my Z-Program is calling multiple synchronous ABAP Proxies/scenarios 1 after another.

My requirement is that if second/third/fourth users are also trying to call same Z program , all Proxy calls for first user should gets completed first then call for second users start.

I know queue management is not possible in synchronous communication due to which I put a lock object in start of first proxy call and releasing it once last proxy call gets completed. Other user must not able to call first proxy until lock is released.

However above locking is not working , when multiple users are executing same program at a same time without a delay of even 1 second.

Kindly help how to stop multi processing of same proxy calls by multiple users from different sessions.

Example - 1

User - 1 - Program - A , Session - 1

Lock

Call Proxy 1 - read table - Z

Call Proxy 2

Call Proxy 3 - update table - Z

Unlock

Example - 2

User - 2  - Program - A , Session - 2

Check Object is not lock

Call Proxy 1 - read table - Z

Call Proxy 2

Call Proxy 3 - update table - Z

Unlock

In above situation user -2 should not be able to call second session of proxies until work of user - 1 gets completed but unfortunately this is not happening. User - 2 is able to view same data in table z  which user 1 reviewed before updating the table, i.e. User - 2 is able to execute Proxy 1 call before data gets saved in table Z by user -1.

[adnanmaqbool · Accepted solution]

Dear All

Issue is resolved by creating a lock over program itself instead of using tables lock.

That is program will remain lock until last proxy call gets executes successfully.

[former_member229310]

Hello,

I would suggest you to create a custom table and use  enque and deque to set the status field for each user run.

Verify if the table has the flag then provide a delay and execute the loop for 5 times and come out incase if the  first user is still executing else you can set and clear after each run.

Handle the table updates correctly else you will have issues.

Hope might be helpful.

[adnanmaqbool]

Dear Hari

Thanks for your response.

If you see , I am using same locking mechanism but its not working. Can you please confirm me lock type i.e. exclusive , shared , exclusive non cumulative.

I am using exclusive non cumulative.

[engswee]

You should probably have asked this in the space instead.

Anyway, you might need to share the code you have as well as the lock object details.

[adnanmaqbool]

Dear Swee

Issue may not be related to locking.

I guess locking is working but the Synchronous Proxy interface at PI end is not getting completed and second user is able to read same third party table which first user is writing.

Exact Scenario.

First User is writing last number of a number range in third party table.

Second User is reading last stored number to generate next numbers but second user is able to read old number instead of number which first user is writing.

Above issue is appearing , if both users are able to execute proxy at a same time other wise working fine.

[adnanmaqbool]

Code is attached..

DO.

    CLEAR: zenq, zenq[].

    SELECT SINGLE *

      FROM zp6lock

      INTO wa_lock

      WHERE proj = '1'.

    IF sy-subrc NE '0'.

      lock = space.

    ELSE.

      lock = 'X'.

    ENDIF.

    CALL FUNCTION 'ENQUEUE_READ'

      EXPORTING

        gclient               = sy-mandt

        gname                 = 'ZP6LOCK'

      TABLES

        enq                   = zenq

      EXCEPTIONS

        communication_failure = 1

        system_failure        = 2

        OTHERS                = 3.

    IF sy-subrc <> 0.

* Implement suitable error handling here

    ENDIF.

    IF zenq IS NOT INITIAL OR lock IS NOT INITIAL.

      l_index =  50.

      CALL FUNCTION 'SAPGUI_PROGRESS_INDICATOR'

        EXPORTING

          percentage = l_index

          text       = 'Please wait or Try later, P6 locked by another user'.

      wait up to 4 SECONDS.

    ELSE.

      EXIT.

    ENDIF.

  ENDDO.

      CALL FUNCTION 'ENQUEUE_EZZP6LOCK' "

        EXPORTING

*         mode_zp6lock   = 'E'

          mandt          = sy-mandt

*         PROJ           =

*         X_PROJ         = ' '

*         _SCOPE         = '2'

*         _WAIT          = ' '

*         _COLLECT       = ' '

        EXCEPTIONS

          foreign_lock   = 1

          system_failure = 2

          OTHERS         = 3.

      IF sy-subrc <> 0.

        PERFORM check_lock.

      ENDIF.

      wa_lock-mandt = sy-mandt.

      wa_lock-proj = '1'.

      MODIFY zp6lock FROM wa.

      IF sy-subrc NE '0'.

        MESSAGE 'Retry! P6 is locked by anohter user' TYPE 'S'.

        LEAVE LIST-PROCESSING.

      ENDIF.

    ENDIF.

    PERFORM get_last_wbs_id. "Proxy Call to read

    PERFORM send_new_wbs_id. "Proxy Call to write

      CALL FUNCTION 'DEQUEUE_EZZP6LOCK'

        EXPORTING

          mode_zp6lock = 'X'

          mandt        = sy-mandt.

      wa_lock-mandt = sy-mandt.

      wa_lock-proj = space.

      MODIFY zp6lock FROM wa.

    ENDIF.

[engswee]

It's very hard to analyse this issue without concrete details.

I'd suggest that you check the monitoring logs to see the timestamp of the messages. Can you verify that the proxy request message for second user happens after the response message of the first user?

[former_member229310]

Looking at code i think the exit statemnet might be kicking out of loop and not from your perform.

Coming out of loop it is straight going to PERFORM get_last_wbs  proxy call and so.

Please debug as you are checking lock first and then going to call proxy you should be making a mistake in handlng the loop.

As only when the lock is released you should be hitting Proxy Perform else your control should not hit that part of code.

1) Open 2 session of the progra ... set the lock trigger proxy

2) In the second session try to debug and veridy where there is breaking the logic.

Cheers!!