Liberty: How to change default JPA provider? - websphere-liberty

Question

In order to program against the JPA 2.1 API, I would like to use eclipseLink, rather than the default OpenJPA JPA provider. How can this be achieved in the WAS 8.5 Liberty profile?
I tried with not using the jpa-2.0 feature and setting up a shared library which is referenced by my webapp, but with no success.
Here's my server.xml:
<server description="new server">
<!-- Enable features -->
<featureManager>
<feature>jsp-2.2</feature>
<feature>localConnector-1.0</feature>
</featureManager>
<httpEndpoint host="localhost" httpPort="9080" httpsPort="9443"
id="defaultHttpEndpoint" />
<applicationMonitor updateTrigger="mbean" />
<webApplication id="System" location="System.war" name="System">
<classloader commonLibraryRef="mysql" />
<classloader commonLibraryRef="eclipseLink" />
</webApplication>
<library id="mysql" name="mysql-jdbc-driver">
<fileset dir="C:\Users\jacomac\.m2\repository\mysql\mysql-connector-java\5.1.26" includes="*.jar"/>
</library>
<library id="eclipseLink" name="eclipse-jpa-impl">
<fileset dir="C:\Users\jacomac\.m2\repository\org\eclipse\persistence\eclipselink\2.5.2-M1" includes="*.jar"/>
<fileset dir="C:\Users\jacomac\.m2\repository\org\eclipse\persistence\javax.persistence\2.1.0" includes="*.jar"/>
<fileset dir="C:\Users\jacomac\.m2\repository\org\eclipse\persistence\commonj.sdo\2.1.1" includes="*.jar"/>
</library>
</server>
This is the error I get:
java.lang.NoClassDefFoundError: javax/persistence/Persistence
An addition: I know it works if I supply the eclipseLink libraries in my webapp, but I would like to use it as a shared resource across multiple webapps.

Answer 1

Liberty 8.5.5.x only seems to support JPA 2.0 even if EclipseLink supports JPA 2.1.
To have Liberty use EclipseLink, in a shared library, you need to set a "parentLast" classloader. My example use an ear but you can also set a classloader for a war.
You should only include eclipselink.jar and let Liberty use its own implementation of javax.persistence.
server.xml:
<fileset dir="${shared.resource.dir}/EclipseLinkLibs" id="EclipseLinkFileset" includes="eclipselink.jar"/>
<library filesetRef="EclipseLinkFileset" id="EclipseLinkLib"/>
<enterpriseApplication id="myEAR" location="myEAR.ear" name="myEAR">
<classloader delegation="parentLast" commonLibraryRef="EclipseLinkLib"/>
</enterpriseApplication>
You also need to set EclipseLink as the provider in persistence.xml:
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
Depending on your EclipseLink version and use of JTA you may also have to consider this bug and use the suggested workaround:
WebSphereTransactionController does not handle JTA on WebSphere 8.5

Answer 2

As of WebSphere Liberty 8.5.5.6 EE7 support was introduced, which includes JPA 2.1 support. With JPA 2.1 feature (jpa-2.1), we changed the default JPA Provider to Eclipselink 2.6.
OpenJPA is still available, and is the default JPA Provider, with the jpa-2.0 feature, which itself is forward compatible with the other EE7 features to support those who do not want to move their JPA-enabled applications off of OpenJPA and do not need to take advantage of the capabilities added by JPA 2.1.
Bear in mind that only one JPA feature can be enabled at one time, so using jpa-2.0 with EE7 features requires enabling individual features rather than using the EE7 convenience feature.