Asynchronous transactions that are exchanged using either publish channels or enterprise services, use Java Message Service (JMS) queues to exchange data with an external system.
For inbound processing, when an enterprise service message is received, the message is immediately written to a JMS queue and the caller of the service is released from the transaction. The message is processed from the inbound JMS queue, through the application business objects, and saved to the database. Messages remain in an inbound queue until they are successfully processed or until they are deleted from the queue. A common strategy for inbound queue implementation is to isolate the queues and the queue consumers to a separate server, or server cluster. This strategy ensures that inbound message-processing does not have a performance impact on application users.
For outbound processing, messages sent out using a publish channel are written to a JMS queue and the user who initiated the message is released from the transaction. The message is processed from the outbound JMS queue using the configured endpoint, and is delivered to the external application. Messages remain in the outbound queue until they are successfully delivered to the external application or are deleted from the queue.
There are three default message queues:
A JMS queue implementation can operate on a single application server or across a cluster of application servers.