Could you explain a little more what you mean by using cross context dispatchers?
Re HTTPClient, do you mean interacting with JForum by issuing HTTP requests to jforum, i.e. the main web app pretends to be filling in one of the form pages in jforum, so would have to simulate login etc.?
In my test environment I already have a jforum webapp using the ROOT webapp SiteMesh decorators (i.e. cross-context). However the main webapp has a large API behind it with its own persistence (and caching). What I had in mind was that the persistence layer for the main webapp would make API calls into jforum to replicate changes to users etc.
Perhaps I should explain a little of the background: my existing site already has users who have profiles etc. There's a forum, an image gallery, store etc almost all of which is bespoke. I'm hoping to use jforum so that I can do away with the bespoke forum. However I am also trying to avoid merging the two applications and instead keep jforum in its own "jforum" web context independently of "ROOT". I would prefer to avoid merging the projects, but perhaps that would be the best approach and then I can achieve exactly what I want, admittedly at the expense of not being able to upgrade jforum easily?
If I merge jforum into my main webapp, I will end up modifying jforum so that the jforum servlet is mapped to /jforum/* and not to /*.page - doing this keeps jforum neatly separated from the rest of the application. (I'll also end up moving all its folders into a WEB-INF/jforum/ so they don't conflict or get muddled up with folders already in the application.). But it would be shame to do all that when it's probably not of interest to anyone else!
Any advice or suggestions would be most gratefully received!