What is the difference between GenericServlet and HTTPServlet?
GenericServlet is an abstract class that defines a generic, protocol-independent servlet.Any protocol dependent servlet has to extend this class in order to provide a specific implementaion and override service method.e.g . HTTPServlet class extends GenericServlet class.
GenericServlet has a service(ServletRequest req, ServletResponse res) method which is called by the servlet container to allow the servlet to respond to a request.
HttpServlet extends GenericServlet and adds support for doGet(), doPost(), doHead() methods (HTTP 1.0) plus doPut(), doOptions(), doDelete(), doTrace() methods (HTTP 1.1). Both these classes are abstract.