Javadoc
Continuation.
A continuation is a mechanism by which a HTTP Request can be
suspended and restarted after a timeout or an asynchronous event
has occured.
Blocking continuations will block the process of the request during a
call to
#suspend(long).
Non-blocking continuation can abort the current request and arrange for it
to be retried when
#resume() is called or the timeout expires.
In order to supprt non-blocking continuations, it is important that
all actions taken by a filter or servlet before a call to
#suspend(long) are either idempotent (can be retried) or
are made conditional on
#isPending so they are not performed on
retried requests.
With the appropriate HTTP Connector, this allows threadless waiting
for events (see
org.mortbay.jetty.nio.SelectChannelConnector).