Network Deployment (Distributed operating systems), v8.0 > Applications > Messaging resources > Message-driven beans - automatic message retrieval
Message-driven beans, activation specifications, and listener ports
Guidelines, related to versions of WAS, to help you choose when to configure your message-driven beans to work with listener ports rather than activation specifications.
We can configure the following resources for message-driven beans:
- Activation specifications for message-driven beans that comply with Java EE Connector Architecture (JCA) v1.5.
- The message listener service, listener ports, and listeners for any message-driven beans to deploy against listener ports.
Activation specifications are the standardized way to manage and configure the relationship between an MDB running in WAS and a destination in WebSphere MQ. They combine the configuration of connectivity, the JMS destination and the runtime characteristics of the MDB, within a single object.
Activation specifications supersede the use of listener ports, which became a stabilized feature in WAS v7.0 (for more information, see Stabilized features). There are several advantages to using activation specifications over listener ports:
- Activation specifications are simple to configure, because they only require two objects: the activation specification and a message destination. Listener ports require three objects: a connection factory, a message destination, and the message listener port itself.
- Activation specifications are not limited to the server scope. They can be defined at any administrative scope in WAS. Message listener ports must be configured at the server scope. This means that each server in a node requires its own listener port. For example, if a node is made up of three servers, three separate listener ports must be configured. Activation specifications can be configured at the node scope, so in the example only one activation specification would be needed.
- Activation specifications are part of the Java Platform, Enterprise Edition Connector Architecture 1.5 standards specification (JCA 1.5). Listener port support in WAS makes use of the application server facilities interfaces defined in the JMS specification, but is not part of any specification itself.
For WAS v7 and later, listener ports are stabilized. For more information, read the article on stabilized features. You should plan to migrate your WebSphere MQ message-driven bean deployment configurations from using listener ports to using activation specifications. However, you should not begin this migration until you are sure the application does not have to work on application servers earlier than WAS v7. For example, if we have an application server cluster with some members at v6.1 and some at v7, you should not migrate applications on that cluster to use activation specifications until after you migrate all the application servers in the cluster to v7.
To use message-driven beans with a messaging provider that does not have a JCA 1.5 resource adapter, you cannot use activation specifications and therefore 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 WAS, to help you choose when to use listener ports rather than activation specifications:
- WAS v4 does not support message-driven beans, so listener ports and activation specifications are not applicable. WAS v4 does support message beans, but these are not message-driven beans.
- WAS v5 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).
- WAS v6 continues to support message-driven beans that are deployed to use listener ports, and also supports JCA, which you can use to deploy message-driven beans that use activation specifications. This gives you the following options for deploying message-driven beans on WAS v6:
- We must deploy default messaging (service integration bus) message-driven beans to use activation specifications.
- We must deploy WebSphere MQ message-driven beans to use listener ports.
- We can deploy third-party messaging message-driven beans to use either listener ports or activation specifications, depending on the facilities available from your third-party messaging provider.
- WAS v7.0 or later continues to support the same options for message-driven bean deployment that WAS v6 supports, and adds a new option for WebSphere MQ message-driven beans. This gives you the following options for deploying message-driven beans on v7.0 or later:
- We must deploy default messaging (service integration bus) message-driven beans to use activation specifications.
- We can deploy new and existing WebSphere MQ message-driven beans to use listener ports (as on WAS v6) or to use activation specifications.
- We can deploy third-party messaging message-driven beans to use either listener ports or activation specifications, depending on the facilities available from your third-party messaging provider.
To assist in migrating listener ports to activation specifications, the WAS administrative console provides a Convert listener port to activation specification wizard on the Message listener port collection panel. This allows you to convert existing listener ports into activation specifications. However, this function only creates a new activation specification with the same configuration used by the listener port.
It does not modify application deployments to use the newly created activation specification.
Message-driven beans - automatic message retrieval
Message-driven beans - JCA components
J2C activation specification configuration and use
Message-driven beans - listener port components
Migrate a listener port to an activation specification for use with the WebSphere MQ messaging provider
Configure an activation specification for a third-party JCA resource adapter
Configure an administered object for a third-party JCA resource adapter
Manage message listener resources for message-driven beans
Configure an activation specification for the default messaging provider
Deploy an enterprise application to use message-driven beans with JCA 1.5-compliant resources
Deploy an enterprise application to use message-driven beans with listener ports
Concept topic