PersistenceUnit.unitName - JPA annotation element

Annotation Element
String unitName

(Optional) The name of the persistence unit as defined in the persistence.xml file. If specified, the persistence unit for the entity manager factory that is accessible in JNDI must have the same name.
Default value:
JPA 1.0

This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink)
and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
ObjectDB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.