Message Driven Bean EJB Glassfish Netbeans
Using Converters, Listeners, and Validators. Developing with JavaServer Faces Technology.
Composite Components: Advanced Topics and Example. Configuring JavaServer Faces Applications. Uploading Files with Java Servlet Technology.
Internationalizing and Localizing Web Applications. Getting Started with Enterprise Beans. Using the Embedded Enterprise Bean Container. Getting Started Securing Web Applications. Getting Started Securing Enterprise Applications.
A message-driven bean is an enterprise bean that allows Java EE applications to process messages asynchronously. This type of bean normally acts as a JMS message listener, which is similar to an event listener but receives JMS messages instead of events.
The messages can be sent by any Java EE component an application client, another enterprise bean, or a web component or by a JMS application or system that does not use Java EE technology.
Message-driven beans can process JMS messages or other kinds of messages. The most visible difference between message-driven beans and session beans is that clients do not access message-driven beans through interfaces.
EJB - Message Driven Beans
Interfaces are described in the section Accessing Enterprise Beans. Unlike a session bean, a message-driven bean has only a bean class. All instances of a message-driven bean are equivalent, allowing the EJB container to assign a message to any message-driven bean instance.
The container can pool these instances to allow streams of messages to be processed concurrently. The instance variables of the message-driven bean instance can contain some state across the handling of client messages, such as a JMS API connection, an open database connection, or an object reference to an enterprise bean object.
Client components do not locate message-driven beans and invoke methods directly on them. Instead, a client accesses a message-driven bean through, for example, JMS by sending messages to the message destination for which the message-driven bean class is the MessageListener.
Chapter 17 A Message-Driven Bean Example
They do not represent directly shared data in the database, but they can access and update this data. The onMessage method can call helper methods or can invoke a session bean to process the information in the message or to store it in a database.
A message can be delivered to a message-driven bean within a transaction context, so all operations within the onMessage method are part of a single transaction. If message processing is rolled back, the message will be redelivered.
Message Driven Bean Example
Session beans allow you to send JMS messages and to receive them synchronously but not asynchronously. To avoid tying up server resources, do not to use blocking synchronous receives in a server-side component; in general, JMS messages should not be sent or received synchronously.
To receive messages asynchronously, use a message-driven bean.
All rights reserved. Legal Notices. What Is a Message-Driven Bean? When to Use Message-Driven Beans.
Create Message Driven Bean
The Java EE 6 Tutorial. In several respects, a message-driven bean resembles a stateless session bean. A single message-driven bean can process messages from multiple clients.
Message-driven beans have the following characteristics. They execute upon receipt of a single client message. They are invoked asynchronously.
What Is a Message-Driven Bean?
They are relatively short-lived. They can be transaction-aware. They are stateless. Overview 2.
Sample Message-Driven Bean XML Files
Getting Started with Web Applications 4. JavaServer Faces Technology 5. Introduction to Facelets 6. Expression Language 7. Using Converters, Listeners, and Validators 9. Developing with JavaServer Faces Technology Composite Components: Advanced Topics and Example Configuring JavaServer Faces Applications Java Servlet Technology Uploading Files with Java Servlet Technology Introduction to Web Services Getting Started with Enterprise Beans Running the Enterprise Bean Examples A Message-Driven Bean Example Using the Embedded Enterprise Bean Container Running the Persistence Examples The Java Persistence Query Language Getting Started Securing Web Applications Getting Started Securing Enterprise Applications Transactions Resources and Resource Adapters The Resource Adapter Example Java Message Service Concepts Java Message Service Examples Bean Validation: Advanced Topics Duke's Bookstore Case Study Example Duke's Tutoring Case Study Example