Systems and methods for composite persistence units

摘要

In an EclipseLink environment, persistence units are associated with a single data source. However, in accordance with an embodiment, a user can define multiple persistence units, each with a different set of entity types (i.e., classes) stored in multiple data sources, and expose them through a single composite persistence unit which combines the entities from across the multiple data sources through a single persistence context. A plurality of different types of data sources can be used, including Java Transaction API (JTA) and non-JTA data sources as well as EclipseLink's native JDBC connection pools. Each member persistence unit continues mapping its classes to its own data source. Therefore, a composite persistence unit allows one to map different entities to different data sources. Composite persistence units can be created at runtime.

主权项

1. A server system, comprising:
a computer including one or more microprocessors; a composite persistence unit, executing on the computer, that includes a plurality of member persistence units,
wherein each of the plurality of member persistence units includes a different set of objects and is associated with a different data source,wherein states of the different set of objects are persisted to the different data source, andwherein the composite persistence unit provides a persistence context which configures queries and transactions to be performed across a combined set of objects from the plurality of member persistence units; a configuration file for the composite persistence unit, wherein the configuration file
defines properties of each of the plurality of member persistence units, including a property for determining whether a persistence unit is a member persistence unit of the composite persistence unit, andspecifies a dependency or reference relationship between one or more objects in a first member persistence unit of the composite persistence unit and one or more objects in a second member persistence unit of the composite persistence unit, wherein the one or more objects in the first member persistence unit include one or more references to, or depend on data received from, the one or more objects in the second member persistence units; and an entity manager created using the composites persistence unit, wherein the entity manager
serves as an interface to the composite persistence unit,operates to manage the member persistence units therein, andmaps a request received by the entity manager to an appropriate member persistence unit.