What is Servlet chaining?

Answer 1

Servers handles the http requests in a Java Web service. you can write multiple servlets to do multiple tasks. But you can also tell the web server to process the request in way of assembly line. For example one servlet might do authentication part, after that other server might to actually processing part, and the third one might customise the response and so on.

Answer 2

Servlet chaining is a technique in which two or more servlets can cooperate in servicing a single request.  In servlet chaining, one servlet's output is piped to the next servlet's input. This process continues until the last servlet is reached. Its output is then sent back to the client.