Transaction demarcation is a big topic. Handling and programming transactions can be done in many different ways. Basically, you want to identify what is a "transaction" in terms of your application. You would first need to get a good understanding of the definition of a "transaction."
Once you have identified the transaction, you then need to look at the operations of the transaction and which methods implement those operations.
Next, you need to look at how you have designed the business logic and the database logic and look at the business methods and the persistence methods.
Check out the
Java Transaction API for more info. Below is an example for study:
[ December 02, 2008: Message edited by: James Clark ]