HttpServlet overrides the service() method to handle HTTP requests and dispatch them to one of the doXXX() handler methods depending on the Http request type (GET, POST, PUT, DELETE, HEAD, OPTIONS, TRACE).
Following are the seven doXXX() methods that the request is dispatched to from the service() method.
doGet() : Handles Http GET requests
doPost() : Handles Http POST requests
doPut() : Handles Http PUT requests
doDelete() : Handles Http DELETE requests
doHead() : Handles Http HEAD requests
doOptions() : Handles Http OPTIONS requests
doTrace() : Handles Http TRACE requests
