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Enterprise JavaBeans in Java Create ANSI/AIM Code 39 in Java Enterprise JavaBeans

Enterprise JavaBeans using barcode maker for jsp control to generate, create code 39 image in jsp applications. QR Code Spevcification As can be seen in jsp Code-39 the example, we declare that the session bean uses bean-managed transactions by decorating the class with the @TransactionManagement annotation, and using TransactionManagementType.BEAN as the value for its value attribute (The only other valid value for this attribute is TransactionManagementType. CONTAINER, but because this is the default value, it is not necessary to specify it.

) To be able to programmatically control transactions, we inject an instance of javax. transaction.UserTransaction, which is then used in the for loop inside the getNewCustomerId() method to begin and commit a transaction in each iteration of the loop.

If we need to roll back a bean-managed transaction, we can do it by simply calling the rollback() method on the appropriate instance of javax.transaction.UserTransaction.

Before moving on, it is worth noting that even though all the examples in this section were session beans, the concepts explained apply to message-driven beans as well.. Enterprise JavaBean Life Cycles Enterprise JavaBe 3 of 9 barcode for Java ans go through different states in their life cycle. Each type of EJB has different states. States specific to each type of EJB are discussed in the next sections.

. Stateful Session Bean Life Cycle Readers experienc bar code 39 for Java ed with previous versions of J2EE may remember that in previous versions of the specification, session beans were required to implement the javax. ejb.SessionBean interface.

This interface provides methods to be executed at certain points in the session bean"s life cycle. Methods provided by the SessionBean interface include:. ejbActiva te() ejbPassivate() ejbRemove() setSessionContext(SessionContext ctx). [ 308 ]. 9 . The first three m swing Code 39 Full ASCII ethods are meant to be executed at certain points in the bean"s life cycle. In most cases, there is nothing to do in the implementation of these methods. This fact resulted in the vast majority of session beans implementing empty versions of these methods.

Thankfully, in Java EE 5, it is no longer necessary to implement the SessionBean interface; however, if necessary, we can still write methods that will get executed at certain points in the bean"s life cycle. We can achieve this by decorating methods with specific annotations. Before explaining the annotations available to implement life-cycle methods, a brief explanation of the session bean life cycle is in order.

The life cycle of a stateful session bean is different from the life cycle of a stateless session bean. A stateful session bean life cycle contains three states: Does Not Exist, Ready, and Passive, as shown in the following screenshot..

Does Not Exist Ready Passive Before a stateful jar Code39 session bean is deployed, it is in the Does Not Exist state. Upon a successful deployment, the EJB container does any required dependency injection on the bean and it goes into the Ready state. At this point, the bean is ready to have its methods called by a client application.

When a stateful session bean is in the Ready state, the EJB container may decide to passivate it, that is, to move it from main memory to secondary storage; when this happens the bean goes into Passive state.. [ 309 ]. Enterprise JavaBeans If an instance of a stateful session bean hasn"t been accessed for a period of time, the EJB container will set the bean to the Does Not Exist state. By default, a stateful session bean will be sent to the Does Not Exist state after 90 minutes of inactivity. This default can be changed by going to the GlassFish administration console, expanding the Configuration node in the tree at the left-hand side, clicking on the EJB Container node, then scrolling down towards the bottom of the page and modifying the value of the Removal Timeout text field, then clicking on the Save button at the bottom-right of the main page.

. [ 310 ]. 9 . However, this tec jboss Code39 hnique sets the timeout value for all stateful session beans. If we need to modify the timeout value for a specific session bean, we need to include a sun-ejb-jar.xml deployment descriptor in the JAR file containing the session bean.

In this deployment descriptor, we can set the timeout value as the value of the <removal-timeout-in-seconds> element.. < xml version= "1.0" encoding="UTF-8" standalone="no" > <!DOCTYPE sun-ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Application Server 9.

0 EJB 3.0//EN" "http://www.sun.

com/software/ appserver/dtds/sun-ejb-jar_3_0-0.dtd"> <sun-ejb-jar> <enterprise-beans> <ejb>.
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