There are two types of communication between servlets.
Application scoped data
- The RequestDispatcher is called for the sharing of the data among the applications.
- The forward method are used to process the requests and responses sent across the network.
- The forward method send the HTTP request across Servlets and the request is processed by the target Servlet.
- When the servlet engine calls the service method of an HTTP servlet, it passes two objects as parameters:
- HttpServletRequest (the Request object)
- HttpServletResponse (the Response object)
- Servlet communicates with the server and with the client through these objects.
- Servlet reads the Request object from ServletInputStream
- It can obtain information about client environment/server using request object and its method like GET and POST.
- It also calls the response objects through setter method.
Session-scoped communication
- HttpSession object is implemented along with the getAttribute() and setAttribute() methods for accessing of corresponding attributes of the objects.