For example, objects placed into sessions for a distributed app should be serializable. This flag indicates whether the app has been written in accordance with the stricter rules. Essentially, these are init parameters for the application. A place to register servlets and give them names. Previously, each server had a different process for registering servlets, making deployment difficult.
Pass servlets parameters at initialization time.
A new standard way to accomplish what used to be a server dependent process. Servlet load order Specifies which servlets are preloaded, and in what order. URL mapping rules Standardized mappings from URLs to servlets. Session timeout defaults Specify how many minutes of client inactivity can go by before a session times out. File extension to MIME type mappings Override server defaults or add mappings not known to the server.