I have been unsuccessful finding answers/topics in this forum related to the following scenario.

Ours is a distributed high volume data driven SOA system written originally in C and now getting migrating to Java. The database schema is distributed and follows the pattern of one database per top level entity. For e.g: Customer is in CustomerDB, Account is in AccountDB, user in UserDB and so on. There may be related tables to each of these entities in the same database, for e.g: UserDB has UserProfile, etc but as the entire system, the high level domain objects are residing in their own distributed database schemas. Due to database limitations when a table in one schema grows too big, it gets split up and put into its own database, giving it the more resources. A lot of these data model decisions are due to the legacy I won't be able to answer why it has been designed this way. The C services seem to work well in this model and most of the business logic are database centric.

Now that we are moving to Java, we want to take advantage of the OO features and write code rich in OO and not Db centric. The problem now is how do I map my Java entities to DB objects that are residing in multiple databases? I want to be able to navigate through the object graph from Customer to Account to Order etc. I looked at the Hibernate Shards but it only deals with multi-tenancy and partitioning based on the data range, all the databases are still having the same schema.

Any usecase logic would involve call to multiple databases to gather its data and work on it (today it happens as discrete service calls to each of these databases). How do I accomplish mapping Java classes in my application to multiple databse schemas, thereby using all the Hibernate features? Any advise on this problem would be very helpful

Thanks
Sairam

It looks like EclipseLink has a feature called "Composite Persistence Units" to handle this scenario. Is there a Hibernate equivalent for this? Thanks

Sairam

Hibernate experts - can anyone respond??

Hi,

I want to build a multy tenant (seperate schema) application with Hinernate 4.

I cannot find any code examples,

Can you maybe post some examples of yours?

Thanks
Tomer

Sairam
I'm not sure this applies to your particular use case - but I have successfully written applications that connect to multiple disparate database using Hibernate. The solution was to write multiple hibernate.cfg.xml files : hibernate1.cfg.xml, hibernate2.cfg.xml, hibernate3.cfg.xml etc. Together with multiple HibernateUtil classes HibernateUtil1, HibernateUtil2, HibernateUtil3 etc each of which references a specific hibernate.cfg.xml file.

Using this pattern, you can map Customer, Account and User to different database.

From what you indicate though, I suspect that the data mapping is only the start of your problems.

David

David,
Correct. Mapping is not an issue but using those mappings to interpret relationships and creating an object graph, persist it across databases is a problem

Regards,
Sairam

Hi David,

Can you maybe post an example of how you work with seperate HBM files for multiple schemas?

Thank you in advanced,
Tomer