A messaging engine is a server component that provides the core messaging functionality of a service integration bus. A messaging engine manages bus resources and provides a connection point for applications.
Each messaging engine is associated with a server that has been added as a member of a bus. When you add an application server as a bus member, a messaging engine is automatically created for this new member. If you add the same server as a member of multiple buses, the server is associated with multiple messaging engines (one messaging engine for each bus). However, in its simplest form a bus can be realized by a single engine.
Messaging engines are given a name, which is based on the name of the bus member. Each messaging engine also has a universal unique identifier (UUID) which provides a unique identity for the messaging engine. If you delete and recreate a messaging engine, it will have a different UUID and will not be recognized by the bus as the same engine, even though it may have the same name. For example, the recreated messaging engine will not be able to access the data store that the earlier instance used. If you accidentally delete a messaging engine configuration, and save the updated incorrect configuration, you must restore the configuration from a previous configuration backup.
Each messaging engine has its own data store. A messaging engine uses an instance of a JDBC data source to interact with the database that contains the data store for that messaging engine. For further information, see Data stores.
For additional information on stopping messaging engines, refer to the following subtopic.