WebSphere WebSphere Application Server Network Deployment, Version 6.0.x Operating Systems: AIX, HP-UX, Linux, Solaris, Windows

Data stores

Data stores enable messaging engines to preserve operating information and to persist those objects that messaging engines need for recovery in the event of a failure.

A data store consists of the set of tables that a messaging engine uses to store persistent data in a database. Refer to Data store tables for a list of the tables that comprise a data store. All the tables in a data store are held in the same database schema. You can create multiple data stores in the same database only by using a different schema for each data store.

The one-to-one relationship between a messaging engine and a data store means that every messaging engine must have 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. Figure 1 illustrates these relationships.

Figure 1. The relationship between a messaging engine and its data store.A messaging engine uses a JDBC data source to manage the interaction with a data store, which is held in a database

All the tables in the data store must be stored in the same schema. If the schema names are different, a database can hold more than one data store. Although every messaging engine uses the same table names, its relationship with the schema gives each messaging engine exclusive use of its own tables.

A messaging engine persists both volatile and durable data in its data 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. For more information, refer to Message reliability levels. Examples of the data that a messaging engine stores are: messages, transaction states, and communication channel states.

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

Data store topologies

You have several options for the relative location of a data store and its messaging engine. The topology also defines the relationship of a data store with other data stores.

The following options affect your choice of data store topology:

Related concepts
Message reliability levels
Related tasks
Selecting the data store topology

Concept topic

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Last updated: 5 Oct 2005
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