Asynchronous request dispatcher
Asynchronous request dispatcher (ARD) can improve Servlet
response time when slow operations can be logically separated and
performed concurrently with other operations required to complete
the response. ARD enables Java™ servlet programmers to perform standard
javax.servlet.RequestDispatcher include calls for the same request
concurrently on separate threads. These javax.servlet.RequestDispatcher
include calls are completed sequentially on the same thread. ARD is
also useful in low CPU, long wait situations like waiting for a database
connection.