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Message stores

Message stores are important in the operation of messaging engines. To host queue-type destinations, a messaging engine includes a message store where, if necessary, it can hold messages until consuming applications are ready to receive them, or preserve messages in case the messaging engine fails. Each messaging engine has one and only one message store. This can either be a file store or a data store.

A message store enables a messaging engine to preserve operating information and to retain those objects that messaging engines need for recovery in the event of a failure.

A messaging engine preserves both volatile and durable data in its message store. Volatile data is lost when a messaging engine stops, in either a controlled or an uncontrolled manner. Durable data is available after the server restarts. See Message reliability levels - JMS delivery mode and service integration quality of service. A messaging engine stores various types of data, including messages, transaction states, and communication channel states.

When started, a messaging engine obtains configuration information from the WCCM (WebSphere Application Server Common Configuration Model) repository. A messaging engine retrieves all other data from its own file store or data store.

Important: There are currently no facilities available for migrating from a data store to a file store.


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