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    <p>Transactions in Java EE must be explicitly controlled, either using the <code>UserTransaction</code> from JNDI or using deployment descriptor/annotations on EJBs. For a CDI component, here the <code>UserController</code>, no transaction is started by default. (<strong>EDIT</strong> Transactions for EJB methods are enabled by default, if nothing is specified.)</p> <p>So to start, your assumption:</p> <blockquote> <p>the <code>UserController.updateUser()</code> will execute <code>userService.saveUser(user);</code> and <code>logService.logEvent("Saved user " + fullName)</code>; within the same transaction</p> </blockquote> <p>is wrong! I believe that a new transaction will be created and committed on each <code>em.persist()</code>/<code>em.merge()</code> call.</p> <p>In order to wrap the calls <code>saveUser()</code> and <code>logEvent()</code> in the same transaction you can manually use the <code>UserTransaction</code>:</p> <pre><code>public void updateUser(user) { InitialContext ic = new InitialContext(); UserTransaction utx = (UserTransaction) ic.lookup("java:comp/UserTransaction"); utx.begin(); ... utx.commit(); // or rollback(), wrap them in try...finally } </code></pre> <p>Or the friendlier:</p> <pre><code>@Resource UserTransaction utx; ... public void updateUser(user) { utx.begin(); ... utx.commit(); // or rollback(), wrap them in try...finally } </code></pre> <p>Or even better the <code>@Transactional</code> annotation, either with Java EE 7 or in Java EE 6 with the <a href="http://deltaspike.apache.org/jpa.html" rel="nofollow">DeltaSpike JPA extension</a> (or any other similar interceptor).</p> <pre><code>@Transactional public void updateUser(user) { ... } </code></pre> <p>You could specify that the EJB methods are transactional using the <code>javax.ejb.TransactionAttribute</code> annotation. There would still be 2 transactions in this case. Alternatively you could move the "business" logic from the web-tier to the EJB-tier in a method annotated with <code>@TransactionAttribute</code> and achieve running the DB methods in a single transaction.</p> <p>As for further reading, check out the "Support for Transactions" chapter in the EJB 3 spec.</p>
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    1. POHow does Java EE container control transactions?
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    1. USArjan Tijms
    1. USNikos Paraskevopoulos
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    1. COYour comment that you must 'activate' EJB transactions using an XML DD is wrong. By default a DD is *optional* and EJB transaction support is active in a container managed environment and a new TX is started when an EJB method is called. There are also rules for TX propagation should that method call other methods on other EJB or on itself (via SessionContext wrapper or self injected instance). The use of the `@TransactionAttribute` annotation is optional in CMT, `@TransactionAttribute(TransactionAttribute.REQUIRED)` is assumed by default.
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    2. COIn my last comment, `@TransactionAttribute(TransactionAttribute.REQUIRED)` should have been `@TransactionAttribute(TransactionAttributeType.REQUIRED)`
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    3. COYour comment that a new TX is created with each call to .persist() or .merge is **WRONG**. You can have as many persists or merges as you want in a TX. In CMT by default the TX boundary is the EJB method, and it can have as many persists or merges as you want. Also the TX _can be_ propagated to other EJB methods and by default it is the same TX, however, this TX propagation can be controlled via the use of @TransactionAttribute annotations on the called EJB classes/methods.
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