Question

I have a JSF application that makes much use of session-scoped variables. A new requirement is that the user should be able to open N numbers of the application. However, since much of the state is session-scoped, when the client opens a 2nd instance of the app, view data from the first app bleeds into the newly opened app.

At this point, changing all the session-scoped beans to request-scoped beans would be very difficult. Is there a way to solve this problem at a higher level, by perhaps mapping external (client) sessions with one or more internal (artificially created and used by JSF) session objects?

Answer 1

You can control how the session is provided to the JSF application via the FacesContextFactory (which provides the FacesContext which contains the ExternalContext). This needs to be configured in a faces-config.xml so JSF can pick it up during initialization. If you use a constructor of the form MyFacesConfigFactory(FacesConfigFactory) JSF will pass the previously configured factory, allowing you to decorate the underlying implementation.

Some issues you may encounter:

• You would need control over what it means to ‘open the application’ in order to create a sub-session. For example, a form that creates the sub-session.
• You need some mechanism to match requests with your session – probably through the ExternalContext URL encoding methods (which will need to be used religiously; well behaved components already use these).
• You need a whole layer of session management code – I’m thinking about folks creating huge HTTP sessions just by opening multiple ‘instances’ of the app.
• There are probably plenty of edge conditions and other things I didn’t think of.

This is an interesting approach to the problem, but I wouldn’t expect it to be a quick fix.