I have an eCommerce system that uses multiple databases hosted on multiple machines. The Customer and User data is in one database, Inventory data is in another database, and Security related data is in a third database. There are 1:1, 1:n, n:m relationships between tables in each database (relationships between databases).
In the past I have used JPA and EclipeLink to create entity managers and controllers to manage these relationships without a ton of extra queries (such as writing my own JOINs and INSERTs), but it was not easy to figure out nor implement (not a singe reference was found on the Internet as to how to do it).
I have now switched to Hibernate and Spring and am wondering if Hibernate can support such mappings and cross-database management without having to write extra queries and JEE code. My search so far has only answered the question of mapping such relationships between tables in a single database or in multiple schemas within a single DBMS, not different databases hosted on different machines.