GenericServlet Vs HttpServlet

GenericServlet	HttpServlet
Signature: public abstract class GenericServlet extends java.lang.Object implements Servlet, ServletConfig, java.io.Serializable	Signature: public abstract class HttpServlet extends GenericServlet implements java.io.Serializable
GenericServlet defines a generic, protocol-independent servlet.(for  any protocol like FTP, SMTP etc.)	HttpServlet defines a HTTP protocol specific servlet
In GenericServlets you cannot use Cookies or HttpSession, Session tracking is not possible is not possible.	These all are possible in HttpServlet .
Generic servlet overrides service method	Http servlets overrides doGet and doPost methods
To write a generic servlet, you need only override the abstract service method.	To write a http servlet, you need only override the any doXXX(-,-) or service(-,-) method.