How can I get Websphere to find persistence.xml in a jar file rather than META-INF?

Question

I'm building a set of REST services and deploying each service to a separate WAR file. Since each of these services uses the exact same persistence configuration, I've placed my persistence.xml in a jar file (the path of the persistence.xml file in the jar is still /META-INF).

When running this using TomEE (1.7), this works just fine. However, when I try the same thing with WebSphere (8.5.5.x) my persistence units do not get loaded. In the WebSphere log, I get an error that looks like:

[4/27/16 8:54:21:653 EDT] 00000080 JPAApplInfo E CWWJP0029E: The server cannot find the MRO_PU_JTA persistence unit in the Customer_WAR.war module and the DS_APP_EAR application. [4/27/16 8:54:21:654 EDT] 00000080 InjectionBind E CWNEN0035E: The ds.services.helper.AbstractServiceHelper/em reference of type javax.persistence.EntityManager for the component in the Customer_WAR.war module of the DS_APP_EAR application cannot be resolved. [4/27/16 8:54:21:657 EDT] 00000080 ResourceInjec E CWOWB0102E: A JCDI error has occurred: The ds.services.helper.AbstractServiceHelper/em reference of type javax.persistence.EntityManager for the null component in the Customer_WAR.war module of the DS_APP_EAR application cannot be resolved.

When I copy the persistence.xml file from my jar file to the local WAR's META-INF, this error goes away and everything works fine. Since I have a ton of services to deploy this way, I don't want to have to make copies of persistence.xml for every WAR file.

Is there any way to get WebSphere to find my persistence.xml file? Maybe some setting in WebSphere that I haven't been able to find?

Thanks.

Answer 1

Ok, so it seems that this is a duplicate of the following: Sharing a persistence unit across components in a .ear file

Looking at the answer to that question from Pascal Thivent, it becomes fairly obvious what the problem is: In order to get this to work, the jar file that contains the persistence.xml must be present in the /lib directory of the EAR that is being deployed to WebSphere. Apparently, the way it works is that the EAR resolves the persistence.xml file, and when each WAR file attempts to inject the entity manager, it refers to the EAR to do so. This is in contrast to TomEE (which is deploying without an EAR file). In that case the dependency is resolved by the WAR file classloader, so just having the jar file in the classpath of the WAR is sufficient.