After two weeks I explored, googling…trial error…and almost got stuck to resolve issue regarding with the use of BAPI_TRANSACTION_COMMIT…ta da… finally in the right time I got an enlightenment for solving this problem. My problem is about how to handle two BAPI connections when tried to finish tutorial “Handling Transaction with BAPIs in Web Dynpro”. In that tutorial, beside we use BAPI to create document in SAP backend system, we also used BAPI transaction commit. Since there is no explanation in that tutorial, my apps just only can regenerate new booking number but no data can be saved in the database. When I search my booking number in SE16N, the result is zero. Thus, I found a link explain about it: http://scn.sap.com/thread/3184761.
My problem is because when accessing backend system it used two parallel session that after first BAPI is executed, another one just dropped and not longer to be continued.
Then based on above link, I try to change the model connection type.
>> Double click on Model you have.
>> In tab Setting >> Model Setting, change default connectionScope to “UC_SCOPETYPE” by delete directlt the delete one and change into “UC_SCOPETYPE” . This model setting will be used to trigger RFC parallel request connection.