JPA EclipseLink orm.xml and persistence.xml

[Udayan Kumar]

All,

I am new to JPA and using Toplink (Oracle's distribution of the open-source EclipseLink) with JPA annotations . I am a bit confused with the purpose of the orm.xml and persistence.xml.

All the JPA based java classes (representative of each underlying database table) should be cataloged in the orm.xml file or persistence.xml file.

I have seen examples on the internet which have entries sometimes in the orm file and sometimes in the persistence file.

Let me know.

Thanks..

[James Sutherland]

The orm.xml file is an option to use to map your entities instead of using annotations, if you are using annotations then you do not need it.

The persistence.xml should technically list all of the persistent classes using the <class> tag, but if all of your classes are in the same jar file as your persistence.xml, then these will be discovered by default in JEE,
and in JSE if you set <exclude-unlisted-classes>false</exclude-unlisted-classes>.