EntityManager in JNDI - jpa

Question

I need to use different databases in the same Web application, so I can't use a persistent.xml to define the target database. The database changes with the client which is connected.
I found this :
public EntityManager getEntityManager() {
if (em == null}
try{
em = (EntityManager)(new InitialContext())
.lookup("java:comp/ejb/EntityManager");
} catch (Exception e){};
}
return em;
}
at this URL : http://wiki.eclipse.org/EclipseLink/Examples/JPA/EMAPI
My question is now : how recording a EntityManager or a Persistence Unit in the JNDI of GlassFish ?

Answer 1

Suppose that my persistence.xml is:
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="ctx-vendor" transaction-type="JTA">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
</persistence-unit>
</persistence>
We have two use case:
WAR application WEB-INF/web.xml file:
<persistence-context-ref>
<description>JNDI for lookup EntityManager</description>
<persistence-context-ref-name>persistence/ctx-vendor</persistence-context-ref-name>
<persistence-unit-name>ctx-vendor</persistence-unit-name>
<persistence-context-type>Transaction</persistence-context-type>
</persistence-context-ref>
EAR application META-INF/application.xml file:
<application xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/application_7.xsd"
version="7">
<description>My Vendor System</description>
<display-name>vendor-ear</display-name>
<module>
<web>
<web-uri>vendor-rest.war</web-uri>
<context-root>/vendor-rest</context-root>
</web>
</module>
<module>
<ejb>vendor-service.jar</ejb>
</module>
<library-directory>lib</library-directory>
<persistence-context-ref>
<description>JNDI for lookup EntityManager</description>
<persistence-context-ref-name>persistence/ctx-vendor</persistence-context-ref-name>
<persistence-unit-name>ctx-vendor</persistence-unit-name>
<persistence-context-type>Transaction</persistence-context-type>
</persistence-context-ref>
</application>
Stateless Session Bean
#PersistenceContext(name = "persistence/ctx-vendor", unitName = "ctx-vendor")
public class BaseFacade
{ }
#Stateless
#Local(CatalogFacade.class)
public class CatalogFacadeImpl extends BaseFacade implements CatalogFacade
{
}
Tested in Glassfish 4.1