Can I assign the same entity beans to multiple Databases?

PooPooCakes · **Joined:** Wed Dec 07, 2005 2:01 pm **Posts:** 8

Need help with Hibernate? Read this first:
http://www.hibernate.org/ForumMailingli ... AskForHelp

[b]hibernate-entitymanager-3.1beta5[b]

I have a situation where I have a group of entity beans that can be assigned to multiple database instances. I would like to assign what database instance the user is using at runtime.

I've looked at the EnteyManager and Entity Factory stuff and I see no way to override any of the properties such as hibernate.default_catalog at runtime. This would fix my problem.

I also see no way of putting more than one entity manager in the same persistence.xml file. If I could do this I could load my entity manager at runtime using jndi.

The final, and least elegant solution I can think of (and I'm not sure will work) is I could put all my entity beans in a .ejb3 file and include a .par for each entity manager (no classes just persistence.xml). Then I can do the jndi lookup at runtime and get the user connected to the correct database.

Code:

Mystuff.ear
{
-> my beans.ejb
-> dbinstance1.par
     -> META-INF\persistence.xml
-> dbinstance2.par
     -> META-INF\persistence.xml
-> dbinstance3.par
     -> META-INF\persistence.xml
}

public EntityManager getEntityManager(String managerName) throws javax.naming.NamingException
{
    EntityManager entityManager;
    InitialContext jndi = new InitialContext();
    try
    {
         entityManager = (EntityManager) jndi.lookup("java:/EntityManagers/" + managerName);
    }
    finally
    {
          jndi.close();
    }
    return entityManager;
}

Is there an easier solution to my problem than my last proposal? Is there a way to override entity manager properties during session creation or something like that? Is there a way to point multiple entity managers to the same beans without having several .pars?

Thanks!

emmanuel · **Posted:** Mon Dec 19, 2005 7:35 am

you can use Ejb3Configuration to do so, but the DI will not work.
Seleral par and 1 jar can work too

PooPooCakes · **Joined:** Wed Dec 07, 2005 2:01 pm **Posts:** 8

Thanks, emmanuel. I played with the Ejb3Configuration, but I couldn't get it to do what I wanted. The multiple par thing worked so I'll go with that.