JPOX supports 2 modes of operation of db4o - file-based, and client-server based. In order to do so and to fit in with the JDO/JPA APIs we have defined the following means of connection.

The following JDO connection properties will connect to a local file-based DB4O running on your local machine

javax.jdo.option.ConnectionDriverName=
javax.jdo.option.ConnectionURL=db4o:file:{my_db4o_file}
javax.jdo.option.ConnectionUserName=
javax.jdo.option.ConnectionPassword=

In JPOX 1.2.0-beta-1 the "file:" was not required. In JPOX 1.2.0-beta-2 and 1.2.0-beta-4 the "file:" was needed, BUT the filename should be absolute. In later JPOX releases the "file:" is needed and the filename can be absolute OR relative.

The following JDO connection properties will connect as a client to a DB4O server

javax.jdo.option.ConnectionDriverName=
javax.jdo.option.ConnectionURL=db4o:{db4o_host}:{db4o_port}
javax.jdo.option.ConnectionUserName=
javax.jdo.option.ConnectionPassword=

DB4O doesn't itself use such URLs so it was necessary to define this JPOX-specific way of addressing DB4O.