We have an application which uses multiple databases to store the same data for different countries.
For example a Subscription
object might be associated with Germany or Spain. If it's a German subscription, it needs to be stored in a different database to the Spanish subscriptions. The databases are identical in structure, but they have different contents.
We are running on jboss 5, and have a different datasource config (*ds.xml) file for each one, generated dynamically at startup. They are stored in JNDI - so we have DataSourceDE, DataSourceES, etc.
Here's how it should work: if a request comes in saying 'fetch subscription 17 for Germany' then I calculate that the datasource should be DataSourceDE and use JPA / hibernate to go fetch that object from the correct database. There will be a subscription 17 in the Spanish database too, which I don't want in this example.
I can generate the persistence.xml automatically to create the extra persistence units for the datasources, but the Subscription
class is annotated with the following:
@PersistenceContext(unitName="core")
This is not going to work - how can I set the persistence context on the java object dynamically?
What you are trying to achieve is known as Multi-Tenancy . Here is a perfectly suitable tutorial for your question to make it work.
The main idea is to use a Stateless session bean which has a reference to both persistence units. Depending on what has to be done, this bean does a lookup to call the corresponding EntityManager
. Furthermore here:
You can change the persistence context for the EntityManager at runtime like this:
EntityManagerFactory emf =
Persistence.createEntityManagerFactory(persistenceUnitName);
EntityManager em = emf.createEntityManager();
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