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Connecting to Multiple Data Stores

Enterprise Objects makes it easy to work with multiple data stores in a single application. An application often includes enterprise object instances that represent data from different repositories.

The EOObjectStoreCoordinator is the object that manages multiple repositories in a single application. When a fetch is performed, it determines which repository can service the fetch. Similarly, when changes are committed, it determines which repository to save the changes to. When a fault is fired, it determines which repository can service the fault. And, Enterprise Objects is smart enough to generate database-specific or database-optimized SQL expressions within a single application that connects to multiple repositories.

There are, however, a few limitations when using multiple data sources in an application. They include:

• Within an EOModelGroup, all entity names must be unique.

• You can’t model inheritance hierarchies across different data sources.

• You can’t flatten attributes or relationships across data sources.

• Enterprise Objects doesn’t support two-phase commit, so you have to be careful when a saving enterprise objects that are constituted from different data sources in a single invocation of EOEditingContext.saveChanges().

If you understand these limitations, connecting to multiple data stores in an Enterprise Objects application should just work.

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