Head First EJB

How attributes work

1. Mark a method with one of six transaction attributes:

   • Required

   • RequiresNew

   • Mandatory

   • Supports

   • NotSupported

   • Never

   

2. When the method is called, the container uses the attribute to do one of five things:

   • Run the method in the caller’s transaction.

     OR

   • Suspend the caller’s transaction and start a new transaction.

     OR

   • Suspend the caller’s transaction and run the method without a transaction.

     OR

   • Throw an exception because the caller does not have a transaction.

     OR

   • Throw an exception because the caller does have a transaction.

     void go() {
         aFooBean.setFoo();
     }

     

Know your attributes

How an attribute affects behavior depends on one thing:

Is the calling method in a transaction?

1. Method foo() is in a transaction (tx A).

   

2. Method bar() is marked with the Required transaction attribute.

   <method>
      <ejb-name>MyBean</ejb-name>
      <method-name>bar</method-name>
   </method>
   <trans-attribute>Required</trans-attribute>

   Note

   The bar() method runs in the same transaction as foo() because bar() is marked Required and foo() has a ...