ServetContext
Internal
Overview
The ServletContext defines a set of methods that a servlet uses to communicate with its servlet container, for example, to get the MIME type of a file, dispatch requests, or write to a log file.
There is one context per "web application" per Java Virtual Machine. In the case of a web application marked "distributed" in its deployment descriptor, there will be one context instance for each virtual machine. In this situation, the context cannot be used as a location to share global information (because the information won't be truly global). Use an external resource like a database instead.
The ServletContext object is contained within the ServletConfig object, which the Web server provides the servlet when the servlet is initialized.
To allow web applications to operate independently, session are scoped at the web application level. This means each ServletContext maintains its own pool of HttpSession instances, and a servlet running inside one context cannot access session information saved by a servlet in another context.