- Stateless Session Beans
- Stateful Session Beans
- Session Bean Client Interfaces
- Session Bean Configuration and Deployment
- Conclusions
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Session Bean Configuration and Deployment
In the last article, I introduced the basic top-level structure of an EJB application module deployment descriptor. The root <ejb-jar> element contained an <enterprise-beans> element, which could contain a collection of <session> elements. Each <session> element is used to describe the configuration and deployment of an individual session bean.
The <session> bean element, shown in Listing 2, defines session bean metadata, a unique name in the EJB JAR file, the bean's class and interface names, the type of session bean, configuration parameters, references to other EJBs and database connections, security semantics, and a transaction flag. The session-related elements of an example stateful session bean's ejb-jar.xml file are shown in Listing 2. You'll note that in addition to standard metadata and structural information about the EJB, it has defined <ejb-ref> elements for all the EJBs that it accesses as a client to those beans.
Listing 2 Example of EJB Session Bean Deployment Descriptor Information
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ejb-jar PUBLIC '-//Sun Microsystems, Inc.//
[ic:ccc]DTD Enterprise JavaBeans 1.1//EN'
[ic:ccc] 'http://java.sun.com/j2ee/dtds/ejb-jar_1_1.dtd'>
<ejb-jar>
<description>A wacky example</description>
<display-name>CartJar</display-name>
<enterprise-beans>
<session>
<description/>
<display-name>ShoppingCartSessionEJB</display-name>
<ejb-name>ShoppingCartSessionEJB</ejb-name>
<home>ejava.ejbch36.shoppingcart.ShoppingCartSessionHome</home>
<remote>ejava.ejbch36.shoppingcart.ShoppingCartSession</remote>
<ejb-class>
ejava.ejbch36.shoppingcart.ShoppingCartSessionEJBean
</ejb-class>
<session-type>Stateful</session-type>
<transaction-type>Container</transaction-type>
<ejb-ref>
<ejb-ref-name>ejb/tshirt</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<home>ejava.ejbch36.tshirt.TShirtHome</home>
<remote>ejava.ejbch36.tshirt.TShirt</remote>
</ejb-ref>
<ejb-ref>
...
</session>
</enterprise-beans>
...
</ejb-jar>
Vendor-specific deployment descriptor files to configure and deploy session beans are also needed. Developers most often use GUI-based deployment tools provided by vendors to develop such files.