When to use activiation specification vs listener port

Guidelines, related to versions of WebSphere® Application Server, to help you choose when to configure your message-driven beans to work with listener ports rather than activation specifications.
You can configure the following resources for message-driven beans:

* Activation specifications for message-driven beans that comply with Java™ EE Connector Architecture (JCA) Version 1.5.
* The message listener service, listener ports, and listeners for any message-driven beans that you want to deploy against listener ports.

If you want to use message-driven beans with a messaging provider that does not have a JCA 1.5 resource adapter (for example the WebSphere MQ messaging provider or the V5 Default Messaging provider), you cannot use activation specifications and therefore you must configure your beans against a listener port. There are also a few scenarios in which, although you could use activation specifications, you might still choose to use listener ports. For example, for compatability with existing message-driven bean applications. Here are some guidelines, related to versions of WebSphere Application Server, to help you choose when to use listener ports rather than activation specifications:

* WebSphere Application Server Version 4 does not support message-driven beans, so listener ports and activation specifications are not applicable. WebSphere Application Server Version 4 does support message beans, but these are not message-driven beans.
* WebSphere Application Server Version 5 supports EJB 2.0 (JMS only) message-driven beans that are deployed using listener ports. This deployment technology is sometimes called application server facility (ASF).
* WebSphere Application Server Version 6 continues to support message-driven beans that are deployed using listener ports, and also supports JCA, which you can use to deploy message-driven beans using activation specifications. This gives you the following options for deploying message-driven beans on WebSphere Application Server Version 6:
o You must deploy default messaging (service integration bus) message-driven beans using activation specifications.
o You must deploy WebSphere MQ message-driven beans using listener ports.
o You can deploy third-party messaging message-driven beans using either listener ports or activation specifications, depending on the facilities available from your third-party messaging provider.

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