It seems that most people use Hibernate within an J2EE server. In my case, I wish to use Hibernate / Sybase in a multithreaded Java server which is called by means of 1) webservices from several clients and 2) internally by the server, by several threads (i.e. when particular business events occur, etc.) Note that the WebServices server is also multithreaded.

Is Hibernate suited in this kind of setup? Is it threadsafe? What is the best way to organize Hibernate within this architecture?

Thanks for any pointers / ideas!

Hibernate is definitely thread safe. Tomcat/J2EE servers use Hibernate in a threaded manner since each HTTP request is it's own thread. The usual pattern is to have one SessionFactory shared by all threads and each thread (request in Tomcat land) to have its own Session (see ThreadLocal pattern). This pattern is well tested and works well and Hibernate has been built to handle this use case. Therefore I assume the SessionFactory is thread safe while a Session is not ...

Yes: a session factory is threadsafe!!

http://www.hibernate.org/hib_docs/reference/html/architecture.html

By the way: checkout the spring framework, it's can be used as a lightweight server to hold the hibernate session factory... It can run within a j2ee container or without

You might find it useful.