topic Re: problem with dequeue and enqueue in Application Development and Automation Discussions

problem with dequeue and enqueue

Former Member — Thu, 11 Dec 2014 14:25:49 GMT

Hi guys,

i have an issue with OL (Local Object - transaction REBDRO):

I want modify document also if another user is in modify of document.

so I implemented this:

    READ TABLE room_oaol INDEX 1.
    wa_part1 = 'IM'.
    wa_part2 = room_oaol-bukrs.
    wa_part3 = room_oaol-swenr.

    CONCATENATE room_oaol-bukrs wa_part3 room_oaol-smenr

    INTO result RESPECTING BLANKS.

    MOVE result TO wa_part4.

    CALL FUNCTION 'DEQUEUE_EVICAGENERIC'
      EXPORTING
        mode_reca_enqueue_data = 'X'
*        mandt                  = sy-mandt
        part1                  = wa_part1
        part2                  = wa_part2
        part3                  = wa_part3
        part4                  = wa_part4
        x_part1                = abap_true
        x_part2                = abap_true
        x_part3                = abap_true
        x_part4                = abap_true
        _scope                 = '3'
        _synchron              = abap_false
        _collect              = abap_false

        .

....

      CALL FUNCTION 'BAPI_RE_RO_CHANGE'

        EXPORTING
          compcode             = wa_room_oaol-bukrs
          businessentitynumber = wa_room_oaol-swenr
          rentalobjectnumber   = wa_room_oaol-smenr
        TABLES
          arch_rel             = tb_arch_relc
          return               = tb_return.

....

    CALL FUNCTION 'ENQUEUE_EVICAGENERIC'
      EXPORTING
        mode_reca_enqueue_data = 'X'
*        mandt                  = sy-mandt
        part1                  = wa_part1
        part2                  = wa_part2
        part3                  = wa_part3
        part4                  = wa_part4
        x_part1                = abap_true
        x_part2                = abap_false
        x_part3                = abap_false
        x_part4                = abap_false
        _scope                 = '2'
        _wait                  = abap_false
        _collect               = abap_false

      EXCEPTIONS
        foreign_lock           = 1
        system_failure         = 2
        OTHERS                 = 3.

but the 'BAPI_RE_RO_CHANGE' say me that the document is lock!

why? I used dequeue function!

Re: problem with dequeue and enqueue

RaymondGiuseppi — Thu, 11 Dec 2014 14:38:07 GMT

Well, using DEQUEUE FM you revoked your own lock, not the locks of other users (they wouldn't be very happy you know)

Read some document as

The SAP Lock Concept (BC-CST-EQ), SAP Lock Concept, Example: Using the Check Lock Modes and Frequently Asked Questions: Lock Concept. For more information, see: Lock Owners and Function Modules for Lock Requests.

Then change your code

Call the ENQUEUE FM, exit if error
Change the data
Execute a COMMIT WORK or call BAPI_TRANSACTION_COMMIT, it will commit data to database, and also release current locks.


I want modify document also if another user is in modify of document.

Is against rules to preserve database consistencies and is not a legitimate solution, and is not an actual requirement.

Regards,

Raymond

Re: problem with dequeue and enqueue

PeterJonker — Thu, 11 Dec 2014 14:45:50 GMT

You are implementing the lock concept in the wrong way.

You should use ENQUEUE first and when your finished updating you use the DEQUEUE FM.

Now when you leave the BAPI you are locking the database table. Why would you want to lock a database AFTER updates ? Study the lock concept in SAP Help because this is a very very very important part of ABAP programming.

When another user has locked the table (entries) the enqueue FM will give you this message. You can then either leave the program with a message or you can call the ENQUEUE in a WHILE LOOP.

pseudocode:

data: lv_subrc type sysubrc,

counter type i.

lv_subrc = 4.

while lv_subrc <> 0.

call FM enqueue

lv_subrc = sy-subrc.

if lv_subrc <> 0.

counter = counter + 1.

wait for X second. "X can be any amount of seconds, you decide how long this should be

endif.

if counter > 10. "try a maximum of 10 times

exit. "leave the while loop

endif.

endwhile.

* check if the queueing was succesfull

if lv_subrc <> 0.

message something

exit. or stop. or return. "depending on your programm structure

endif.

Re: problem with dequeue and enqueue

Former Member — Thu, 11 Dec 2014 15:03:38 GMT

excuse I explained bad

I want to edit the document while I am in editing the document (not another user).

So, document is locked by me (transaction REBDRO) AND my report can be modify the document.

So, the document is enqueued.

1. dequeued (unlock)

2. modify

3. enqueued (re-lock)

no?i'm worng?

Re: problem with dequeue and enqueue

RaymondGiuseppi — Thu, 11 Dec 2014 15:04:45 GMT

Or remove the WAIT statement, and use the _WAIT parameter of the ENQUEUE FM. Else someone else can successfully lock the object during the wait time.

Regards,

Raymond

Re: problem with dequeue and enqueue

PeterJonker — Thu, 11 Dec 2014 15:11:43 GMT

Yes you are wrong. The lock concept is meant to prevent database inconsistencies NOT to delete a lock because you are using the same data in another program. Why you want to do that anyway is a complete mystery to me, but that is besides the case.

It ALWAYS is:

1. ENQUEUE

2. CHANGE DATA

3. DEQUEUE.

Again read the documentation and learn this properly because this is one of the most important parts you need to know as ABAP developer.

The links have been provided by Raymond.

Re: problem with dequeue and enqueue

Former Member — Thu, 11 Dec 2014 15:23:23 GMT

I want modify the document with 'BAPI_RE_RO_CHANGE' WHILE I am in in editing the document.

So, I know that the document is enqueued! I don't need that if the document is enqueued.

I need to modify the document while I am in editing.

if I click on button "associa OA ad OL" I want modify document through bapi...but the bapi say me that the document is locked.

So, I Dequeued document and after change document ! but it is wrong .

Re: problem with dequeue and enqueue

Former Member — Thu, 11 Dec 2014 15:24:45 GMT

I want modify the document with 'BAPI_RE_RO_CHANGE' WHILE I am in in editing the document.

So, I know that the document is enqueued! I don't need that if the document is enqueued.

I need to modify the document while I am in editing.

if I do enqueued it say me : document is locked ! I know that it is locked.

Re: problem with dequeue and enqueue

PeterJonker — Thu, 11 Dec 2014 15:33:27 GMT

I don't think you can use the BAPI for that, you will need to use a user exit where the data to be changed is available to you, so you can adjust the instance that is already opened in the program. The BAPI wants to open the same instance again but since this is locked it gives an error.

Which user exit are you using now to call the BAPI ?

Re: problem with dequeue and enqueue

RaymondGiuseppi — Thu, 11 Dec 2014 15:47:20 GMT

Did you analyze BAdI BADI_RE_BD_RO (If I did correctly identify the transaction?)

If no useful method in the BAdI interface, then analyze where the transaction stores the currently modified data, and if you find a “safe” solution to modify it.

Or if you don't need to keep the transaction running, just call a RFC enabled FM in BACKGROUND MODE (can be thru a PERFORM ON COMMIT)

So when user save the data, the transaction will execute a COMMIT WORK, update tasks will update the database and then your wrapper FM will execute when locks are released, so you can call BAPI and COMMIT in this FM executed in a new LUW.

NB: Using the BAPI during the transaction call will surely mess the data -> don’t (BAPI may/will reload data from database then update database and refresh some buffer, also commit may/will trigger some partial update prepared by trnasaction, don't even care to imagine the status of the calling transaction at this step...

Regards;

Raymond

Re: problem with dequeue and enqueue

Former Member — Thu, 11 Dec 2014 15:47:33 GMT

when you click on the button "associa OA ad OL" it open a browser.

through the browser you can access to another sistem (for example sistem SREMAP).

SAP --CALL--> SREMAP

On SREMAP You can see other information with OL in object.

When you stay on SREMAP you can modify the document.

So , when you modify the document FROM SREMAP it call web service (function on sap) where there is my bapi_change.

SREMAP --CALL--> SAP

but my bapi_change say me "the document is locked" , because I am in edit of the document.

I know that it is locked.

Now, I need to edit the document by SREMAP while I editing the document.

help me please , thanks

Re: problem with dequeue and enqueue

Former Member — Thu, 11 Dec 2014 16:18:08 GMT

I can't call my fm after save because i need update the data in real time.

Re: problem with dequeue and enqueue

Former Member — Fri, 12 Dec 2014 09:16:13 GMT

I solved the issue with:

    CALL FUNCTION 'ENQUEUE_READ'
      EXPORTING
        gclient               = sy-mandt
        guname                = sy-uname
        gname                 = 'RECA_ENQUEUE_DATA'
        garg                  = garg

      IMPORTING
        subrc                 = subrc

      TABLES
        enq                   = enq

      EXCEPTIONS
        communication_failure = 2
        OTHERS                = 1.

    IF sy-subrc = 0.

      CALL FUNCTION 'ENQUE_DELETE'
        EXPORTING
          check_upd_requests = 1
        IMPORTING
          subrc              = subrc
        TABLES
          enq                = enq.

      REFRESH enq.
      CLEAR enq.

    ELSEIF sy-subrc = 2.
      MESSAGE w116.
    ENDIF.

Re: problem with dequeue and enqueue

PeterJonker — Fri, 12 Dec 2014 10:30:56 GMT

And which data is now going to be saved to the database, the changes you made in the screen or the changes made by the BAPI ?

Did you try a test where you change something in the document FIRST and then click the button which calls this BAPI to see what happens ?

I would not feel comfortable with a solution that you have presented. It goes against the rules of safe programming. You should at least do lots of testing where you make changes in all possible ways to see if your solution can cause any confilcts when updating the database.