The javax.servlet package is the core of the Servlet API. It includes the basic Servlet interface, which all servlets must implement in one form or another, and an abstract GenericServlet class for developing basic servlets. This package also includes classes for communication with the host server and client (ServletRequest and ServletResponse) and communicating with the client (ServletInputStream and ServletOutputStream). The class hierarchy of the javax.servlet package is shown in Figure A?1. Servlets should confine themselves to the classes in this package in situations where the underlying protocol is unknown.

GenericServlet provides a basic implementation of the Servlet interface for protocol? independent servlets. As a convenience, it also implements the ServletConfig interface. Most servlet developers subclass this class or HttpServlet, rather than implement the Servlet interface directly. GenericServlet includes basic versions of the init() and destroy() methods, which perform basic setup and cleanup tasks, such as managing the server's ServletConfig object. It's good form for a servlet that overrides one of these methods to call the superclass version of the method. GenericServlet also includes a log() method that provides easy access to the logging functions from ServletContext.

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