Configuring an EJB 2.1 Transaction Attribute

For an enterprise bean that uses container-managed transactions, you can configure how the container manages transactions when a client invokes a bean method (see "Using Deployment XML").

For more information, see the following:

• "Who Manages a Transaction?"

• "What are Container-Managed Transactions?"

• "How are Transactions Handled When a Client Invokes a Business Method?".

Using Deployment XML

To configure how the container manages transactions when a client invokes a bean method, use the ejb-jar.xml file <assembly-descriptor> subelement <container-transaction>, as Example 21-4 shows.

Example 21-4 Configuring Transaction Attribute for an EJB 2.1 Session Bean

<assembly-descriptor>
    <container-transaction>
        <method>
            <ejb-name>CreditService</ejb-name>
            <method-name>setLimit</method-name>
            <method-params>
                <method-param>int</method-param>
            </method-params>
        </method>
        <trans-attribute>Required</trans-attribute>
    </container-transaction>
...
</assembly-descriptor>

The <container-transaction> element contains one or more <method> elements and one <trans-attribute> element. The <trans-attribute> element applies to all the <method> elements. You can specify methods by name, by name and parameters (signature), or you can specify all methods of the specified enterprise bean using a wildcard <method-name>*</method-name>.

Table 21-2 lists the values for the <trans-attribute> element that you can specify and shows how the container will respond depending on whether or not a client-controlled transaction exists at the time the method is invoked

Table 21-2 Valid Values for the <trans-attribute> Element

Transaction Attribute	Client-Controlled Transaction Exists	Client-Controlled Transaction Does Not Exist
NotSupportedFoot 1	Container suspends client transaction	Use no transaction
SupportsFoot 2	Use client-controlled transaction	Use no transaction
RequiredFoot 3	Use client-controlled transaction	Container starts a new transaction
RequiresNew	Container suspends client transaction and creates a new transaction	Container starts a new transaction
Mandatory	Use client-controlled transaction	Exception raised
Never	Exception raised	Use no transaction

^Footnote 1 Default for EJB 2.1 message-driven beans.

^Footnote 2 Default for EJB 2.1 session beans and BMP entity beans.

^Footnote 3 Default for EJB 2.1 CMP entity beans.