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Message-Driven Bean Configuration and Deployment

In the third article in this series, 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 (new to EJB v2.0) can contain a collection of <message-driven> elements. Each <message-driven> element is used to describe the configuration and deployment of an individual message-driven bean.

The <message-driven> bean element, shown in Listing 1, defines message-driven bean metadata, a unique name of the bean, the bean's class name, configuration parameters, security semantics, transaction semantics, an optional selector statement used to select a particular bean to receive particular messages, a message-acknowledgement mode, and a description of the particular messaging model implied by the bean (topic or queue). The message-driven–related elements of an example message-driven bean's ejb-jar.xml file are shown in Listing 1.

Listing 1 Example of EJB Message-Driven Bean Deployment Descriptor Information

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise
JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd">

 <description>A Message Driven EJB</description>
 <display-name>Asynchronous Beans Example</display-name>
   <display-name>B2B Supply Chain Manager </display-name>

Vendor-specific deployment descriptor files to configure and deploy message driven beans are also needed. Developers most often use GUI-based deployment tools provided by vendors to develop such files.

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