Servlet chaining is a process in which multiple servlets are linked together to handle a single client request. In this process, the output of one servlet is passed as input to the next servlet in the chain. This allows for modularization of code and reusability of servlets, as each servlet in the chain can perform a specific task or transformation on the request or response objects.
There are two primary modes of servlet chaining:
Forwarding Request Mode: In this mode, the request is forwarded from one servlet to another, and only the response from the last servlet in the chain is sent back to the client. The intermediate servlets process the request but do not send any output to the client. This mode is useful when the processing of a request needs to be split among multiple servlets, but only the final processing result should be returned to the client.
Including Response Mode: In this mode, the response from each servlet in the chain is included in the final response. This means that the output of all servlets is combined and sent back to the client. This mode is useful when different servlets are adding content to the response, such as a header, body, and footer.
Servlet chaining is implemented using the RequestDispatcher interface, which provides the forward() and include() methods to support the two modes of chaining. The RequestDispatcher object can be obtained from the ServletRequest object, the ServletContext object, or the ServletConfig object.
The advantages of servlet chaining include the ability to easily undo changes, handle dynamically created content, and mana...
