What is the difference between request attributes, session attributes, and ServletContext attributes?
A ServletContext attribute is an object bound into a context through ServletContext.setAttribute() method and which is available to ALL servlets (thus JSP) in that context, or to other contexts via the getContext() method. By definition a context attribute exists locally in the VM where they were defined. So, they’re unavailable on distributed applications. Session attributes are bound to a session, as a mean to provide state to a set of related HTTP requests. Session attributes are available ONLY to those servlets which join the session. They’re also unavailable to different JVMs in distributed scenarios. Objects can be notified when they’re bound/unbound to the session implementing the HttpSessionBindingListener interface. Request attributes are bound to a specific request object, and they last as far as the request is resolved or while it keep dispatched from servlet to servlet. They’re used more as comunication channel between Servlets via the RequestDispatcher Interface (since you
