derby persistence.xml - eclipselink

Question

What should be the property statement regarding the derby client driver in the persistence.xml e.g :
<property name="javax.persistence.jdbc.driver" value=" ? " />
When tyring to update the DB from Java I keep getting the exception below.
Actually I need the client driver instead the EmbeddedDriver . Don't know how to name it.
The project has in its java Build path/libraries the Derby Client JDBC driver ( eclipse plugin has the derby plugin).
The program instruction causing the exception is :
factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
EntityManager em = factory.createEntityManager();
[EL Info]: 2012-02-02 10:48:44.805--ServerSession(1434473856)--EclipseLink, version: Eclipse Persistence Services - 2.3.2.v20111125-r10461
[EL Severe]: 2012-02-02 10:48:44.93--ServerSession(1434473856)--Exception [EclipseLink-4003] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.DatabaseException
Exception Description: Configuration error. Class [org.apache.derby.jdbc.EmbeddedDriver] not found.
Exception [EclipseLink-4003] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.DatabaseException
Exception Description: Configuration error. Class [org.apache.derby.jdbc.EmbeddedDriver] not found.

Answer 1

javax.persistence.jdbc.driver defines the protocol that shall be used to access the database.
You need to set it like this, if you want to access a remote/local derby network server:
<property name="javax.persistence.jdbc.driver" value="jdbc:derby://localhost:1527/my_schema " />
Where 1527 is the port of your NetworkServer.
And my_schema is your database schema.
If you don't have schema yet, use ;create=true to create it:
jdbc:derby://localhost:1527/my_schema;create=true
You may want to take a look at the Getting Started Guide.
Side note:
Class [org.apache.derby.jdbc.EmbeddedDriver] not found.
This tells you that not all jars needed by derby are present in the classpath(in your comment you state, that this is the case). If you get any such exception, make sure that all jars are actually in the classpath.