A Web application may be deployed either as a WAR file that has been packaged according to the standard layout and containing a web.xml deployment descriptor, or from a directory containing the application's source components arranged in the standard layout.
When deploying a Web application from a directory, you may specify the location of the
web.xml deployment descriptor if it is not in the standard location. You may
also specify the directory used by the server for temporary files. At runtime the web application
has access to the server classes.