7 Transactions

A database transaction is a set of operations (create, read, update, or delete) that either succeed or fail as a single operation. The database discards, or rolls back, unsuccessful transactions, leaving the database in its original state.

In Oracle Application Server TopLink, transactions are encapsulated by the Unit of Work object. Using the Unit of Work, you can transactionally modify objects directly or with a Java 2 Enterprise Edition (J2EE) external transaction controller, such as the Java Transaction API (JTA).

This chapter explains how to use the OracleAS TopLink Unit of Work, including:

• Introduction to Transaction Concepts

• Understanding the Unit of Work

• Unit of Work Basics

• Advanced Unit of Work

• J2EE Integration