Hi everyone,
It's a quick question.

I was wondering. If I have one database, and two application servers, with one webapp on each. Let's call them webapp1 and webapp2. How will hibernate of webapp1 know that a webapp2 has modified or inserted data in the database ?

Thanks in advance

Hibernate determines this using Optimistic Concurrency Control (OCC) and Version checking/timestamp

It depends on how your entities are defined. I assume you use JPA because you talk about app severs? Well, if your entities use the @Version annotation, or the hbm equivalent, then regardless of who concurrently accesses the database (2 apps, 2 modules, 2 threads), only one of them will be able to update the entity, and the other will throw an OptimisticLockException or similar.