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See IBM WebSphere Developer Technical Journal: Leveraging OpenJPA with WebSphere Application Server V6.1.
Also, WebSphere Application Server V6.1 can download and install the EJB3 Feature Pack, which includes OpenJPA 1.0.x.
WebSphere Application Server V7.0 includes OpenJPA 1.2.x and you can simply deploy an enterprise archive, web archive, or EJB-JAR that contains a persistence unit.
The WebSphere Application Server V7 Feature Pack for OSGi Applications and Java Persistence API 2.0 includes OpenJPA 2.0 and provides the JPA 2.0 programming model within Java EE5 and OSGi applications.
Integrating with IBM WebSphere Application Server Community Edition:
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