Process inbound Idocs only one at a time

Question

Hi all,
I'm searching for a solution to the following problem:
We are receiving ORDERS-Idocs into our R/3 4.6C-system. These Idocs are processed by our own Z-function module. The function module's coding should assure that e.g. the first idoc of each day sent by a certain customer should create a new sales order (VA01), whereas the following idocs of that same customer should only add items to that sales order (VA02).
To make this work, we must make sure that no two idocs of the same sender are processed simultaneously, or even better that the function module is running only once at a time. I tried the following practices, which didn't satisfy our needs:
- create own ENQUEUE/DEQUEUE object and call the ENQUEUE at the beginning of my function module - didn't work!
- use GET PARAMETER ID to read a flag and SET PARAMETER ID to set the flag - didn't work, second idoc was too fast!
- write a record into own DB table and check existing entry with SELECT SINGLE FOR UPDATE - worked only sometimes, needs COMMIT WORK.
- check if there are any flags you can set in WE20 - couldn't find any!
Does anyone have a idea for my problem?
Greetings
Klaus

Answer 1

Hi Klaus,
form the mentioned options, I would give enqueue / dequeue a second try.
I would use customer (/sender) as key field for your locking object.
If you try to set the lock right in the beginning of your FM, whole customer should be locked for processing. Second test is of course, if already a sales order exists.
Maybe here the problem occurs: when you have some parts in update task, select for sales order is not successful for some (micro-)seconds.
Solution for this part: use synchronic booking / commit work and wait. Maybe make a test with a select for VBAK in the end of your FM to test existence -> if not successfull, you know you identified your problem.
If this is your problem, you should make a new enqueue after commit (because it will be deleted by commit) and wait until DB gives you new VBAK entry.
I would start with a test, why all this different locking options don't work (instead of looking for a different locking option): make a select after your sales order creation. If this is not successfull, then here is your starting point.
Regards,
Christian