Hi all!

I've failed to find anyone commenting on the fact that the commonly used Hibernate Filter (called Persistance on http://www.hibernate.org/43.html) is insufficient when you're deploying several web applications within the same JVM, and they (need to) use separate SessionFactory instances.

The fix I'm looking at is to set up a static Map that maps request.getServletContext() to SessionFactory objects, instead of a single static reference to a SessionFactory object.

Any suggestions, recomendations or comments is highly appreciated.

(Using Hibernate 2.1.4 and Tomcat 4.1.30.)

It should be trivial to just put the SessionFactory into the ServletContext instead of into a static variable.

Thanks for your suggestion, but I don't see how the filter can get a hold on the ServletContext, all I see is Servlet.getServletConfig().getServletContext() and HttpServlet.getServletContext(). What am I missing? (Or did you suggest that we should skip the filter in the web applications?)

in the init method of a Filter, you can do

filterConfig.getServletContext()

Wait, shouldn't each webapp have its own classloader, therefore each static class variable should be able to point to a different SessionFactory?

Uhm, I know nothing about how the class loader works in either applications (Tomcat, Hibernate) but basic Idea is that there's two (soon more) applications that all need to use the filter approach to ensure sessions are properly set up and closed.

Calls to HibernateFilter.getSession() must not return sessions from the same SessionFactory. With the current implementation, even though there are two filters set up (one for each application/web.xml), only one factory will be used in BOTH applications since they run within the same JVM.

if it can help: we're running many hibernate's webapp in the same tomcat... it works.

anthony: I'd appreciate it greatly if you could explain how the protected static SessionFactory factory class field/variable is UNIQUE among the web applications, because I don't see how that's possible.

Did you even read Michael's response?

http://www.google.com.au/search?q=singl ... assloaders

Read the first article in the list.

Nice link, stolley, I will add it to my collection :)

You just have to make sure your HibernateUtil class or whatever is in two different classloaders. That means you can't share it in something like /common/lib which is bad practice anyways.

Of course, but I wasn't aware of the fact that you could make a "common mistake" as the article you pointed me to calls the ability to allow more than one instance to be created. I simply didn't think beyond what I already knew, my bad.

Thanks all for enlightening me :)