eg. webapp1 and webapp2 are web applications in Tomcat. How to setup Hibernate and Tomcat to make the above 2 web applications share one cache?

thanks.

What are you trying to cache? The sessionFactory? If so, The most recent version of Tomcat ships w/ read only JNDI, so you'll have to switch to a more managed environment like JBoss and role your sleaves up for JTA and HAR deployment.

thanks for your reply.
the cache i want to share is Second Level Cache and Query Cache.

See hibernate configuration properties with "hibernate.cache" prefix and you will need to configure cache provider (TreeCache for example). And do not forget stuff like materialized views, indexes and clusters ( probably you will not need to share any cache ... )

thanks.
i have managed to use cache in each one of the 2 application. but the 2 apps use one db. if i insert a record in app1, sqls that utilize cache in app2 will not get the record just inserted. how can i tell app2 that db is changed and discard the cache accordingly?