11.7.3. Begin a Transaction

This procedure shows how to begin a new JTA transaction, or how to participate in a distributed transaction using the Java Transaction Service (JTS) protocol. For more information about distributed transactions, refer About Distributed Transactions section.

  1. Get an instance of UserTransaction.

    You can get the instance using JNDI, injection, or an EJB's context, if the EJB uses bean-managed transactions, by means of a @TransactionManagement(TransactionManagementType.BEAN) annotation.

    • JNDI

      new InitialContext().lookup("java:comp/UserTransaction")

    • Injection

      @Resource UserTransaction userTransaction;

    • Context

      • In a stateless/stateful bean: 
        @Resource SessionContext ctx;
ctx.getUserTransaction();
      • In a message-driven bean: 
        @Resource MessageDrivenContext ctx;
ctx.getUserTransaction()

  2. Call UserTransaction.begin() after you connect to your datasource.

    ...
try {
    System.out.println("\nCreating connection to database: "+url);
    stmt = conn.createStatement();  // non-tx statement
    try {
        System.out.println("Starting top-level transaction.");
        userTransaction.begin();
        stmtx = conn.createStatement(); // will be a tx-statement
        ...
    }
}
Participate in an existing transaction using the JTS API.

One of the benefits of EJBs is that the container manages all of the transactions. If you have set up the ORB and activated JTS transactions, the container will manage distributed transactions for you.

Result:

The transaction begins. All uses of your datasource until you commit or roll back the transaction are transactional.

Note

For a full example, see Section 11.9.3, “JTA Transaction Example”.
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