A mediation processes inflight messages between the production of a message by one application, and the consumption of a message by another application.
A mediation is associated with a destination to create a mediated destination. A mediated destination has two parts: pre-mediated and post-mediated. Applications send messages to the pre-mediated part, and receive them from the post-mediated part. A mediation receives messages from the pre-mediated part, transforms the messages in some way, and places one or more messages on the post-mediated part. In this way, the mediation controls the progress or otherwise of messages to their intended target destination.
A mediation can operate within a global unit of work to ensure transactional integrity. Several mediations can operate at the same time to improve the throughput of messages at a destination.
When you configure a mediation for use at a particular destination, the physical location is called a mediation point. The message processing provided by the mediation is started when the mediation point receives a message from the messaging runtime. The mediation operates on an instance of the message, for example transforming it, or forwarding it to other destinations.
Mediations operate on messages after the server has started. No new messages are mediated after server shutdown begins.