Use of Adaptive RFC and locking

Question

Hello,
I am using an adaptive RFC model inside a Web Dynpro Application to maintain data residing on a SAP Enterprise system.
This RFC also sets a lock in order to make sure nobody else tries to change the same data.
I use pessimistic locking which means:
1. Web Dynpro calls a RFC
2. The RFC first locks the data then reads the data and returns the result back to Web Dynpro
3. The user changes the data and presses a save button
4. Web Dynpro calls the RFC to write and unlock the data
The problem i have is the fact that after locking and reading of the data the RFC is ended and the data is received by the Web Dynpro App. But at the same moment the lock is automatically unlocked because the RFC has ended succesfully.
How can i achieve that the lock is still there at the moment i want to change the data or is this procedure of pessimistic locking not possible?
Bertil

Answer 1

Hi,
Whether possible or not : Don't know. Probably not with RFCs.
More importantly, shall you do it? If it is transactional data you are updating , you may wish to consider concurrency issues (what if you locked and came to web dynpro, and user is thinking whether he shall take a coffee break first before pressing the 'Save'. Would you like to keep this record(s) locked and unavailable for the entire duration?)
Normally, you would read the data in the first call, let the user update it on the second screen, and then, when the user presses save, execute in sequence :-
- try locking the record,
- if locking is successful, Verify whether the record you read has changed in the meanwhile or not (verify what you have in your workarea(before changes done by user) is the same as in DB, by reading again from the DB)
- If above check is successful, go ahead with the update else throw an error message to the user to redo the txn
- unlock, exit
hope this helps,
cheers,
Ajay