Network fails after committing transaction

Hi,

I have a following situation and not sure how to handle.

I am exposing a web service which has Integration and processing layer as usual.(processing layer has divided in to various layer(validation layer,business logic layer, DAO layer as required for my services)

i am committing transaction in processing layer (DAO layer) after committing the transaction, if network fails ( i mean between client and my service), i have to reverse the transaction. Can you please help