Spring: A Developer's Notebook

Configuring Simple Transactions

Now, you'll see the most useful type of transaction support: declarative transactions. It's time to go back and explain the configuration of the transactions on your façade. In Chapter 4, you configured the transactions without explanation. It's time to go back and fill in the holes.

Declarative transactions are perhaps the most important feature of EJB session beans. Many developers decide not to use EJB at all when they discover that you can in fact use declarative transactions without sacrificing your first-born child.

You will implement declarative transactions without ever touching the code. You only need to change the context. Just like the examples in the previous chapter, you will configure an interceptor. The interceptor defines the methods to be marked as transactional and defines their expected behavior. Some of the methods will use full transaction propagation, and some will use a lighter-weight, read-only propagation (Example 7-3).

Example 7-3. RentABike-servlet.xml

<bean name="transactionInterceptor" class="org.springframework. transaction.interceptor.TransactionInterceptor"> <property name="transactionManager"> <ref local="transactionManager"/> </property> <property name="transactionAttributeSource"> <value> com.springbook.RentABike.transferReservation= PROPAGATION_REQUIRED,-ReservationTransferException com.springbook.RentABike.save*=PROPAGATION_REQUIRED com.springbook.RentABike.*=PROPAGATION_REQUIRED,readOnly </value> </property> </bean> ...