Since your database jar is inside your same EJB ear package, I think it is supposed to be "in the classpath", so you should try following the "in the classpath" section of the docs at http://db.apache.org/derby/docs/10.6/devguide/cdevdvlp24155.html#cdevdvlp24155.
That is, I don't think you want to use the "jar" sub-protocol.
Alternatively, if you are going to use the "jar" sub-protocol, then I think that the part inside the parentheses should be the full filesystem path of your ejb ear file.
Bryan Pendleton
2010-09-30 03:10:56