Hi - I have a web application which has the following:
Web (Struts) + EJB 2.0 (Stateless, Stateful and Entity) + Custom DAO

What are the factors i should consider or plan before I cluster the application.

I hope we should consider these:
1. EJBs
2. Singleton classes (I am not sure how changes made in singleton classes in one server will be reflected in the other).
3. File handling: A component in one server is changing the content in one server. I dont know how it will be reflected in the other server. Should the file be stored in a common place so that all server has access to it. Or is there any way that the files will be automaticaly migrated if you place it in a special folder.

Kindly let me know if I am missing any other factors.