Diffrence b/w sync & async mode in bdc.

Question

hi all,
   wat is the diffrence b/w sync & async mode in bdc? plz explain interview point of view.
regards
deepak

Answer 1

A Asynchronous updating. In this mode, the called transaction does not wait for any updates it produces to be completed. It simply passes the updates to the SAP update service. Asynchronous processing therefore usually results in faster execution of your data transfer program.
S Synchronous updating. In this mode, the called transaction waits for any updates that it produces to be completed. Execution is slower than with asynchronous updating because called transactions wait for updating to be completed. However, the called transaction is able to return any update error message that occurs to your program. It is much easier for you to analyze and recover from errors
one simple example : You are creating sales order from file and also you want to update header text of sales order.
when you want to update sales order header text,you need to use save_text function module ,here you need to pass sales order number.
when you use call transaction update 'A', data will update transaction level and it goes to the next record,here it will not wait for database .
when you use call transaction update 'S',data will update transaction level and it will update database then it goes next record.
if you want to update header text,then you need to use sync update
database commit -
comitt work - it will update data in database sucessfully
roll back - it will not update in database.
Thanks
Seshu