On 24/04/2013 18:38, Rossen Stoyanchev wrote:
----- Original Message -----
From: "Mark Thomas" <ma...@apache.org>
To: "Tomcat Users List" <users@tomcat.apache.org>
Sent: Wednesday, April 24, 2013 12:47:54 PM
Subject: Re: AsyncListener.onError and disconnected client
On 24/04/2013 16:33, Rossen Stoyanchev wrote:
Hi,
I've seen various discussions here and on the web but I haven't
found
a conclusive answer. Why does an AsyncListener not receive onError
notifications when a client disconnects?
Because the Servlet EG says that is the required behaviour. The EG is
currently revisiting that decision. See
https://java.net/jira/browse/SERVLET_SPEC-44
Thanks for that reference. Is there something in the spec that explicitly makes
requires this?
Not that I am aware of which why I said "EG" rather than "specification".
The JIRA ticket is about adding a "disconnect" callback but I can imagine in
the very least, onComplete can be called. After the connection is over.
onComplete should be called once the connection times out.
To my knowledge there is nothing inherent in NIO and TCP that
prevents the server from detecting that the client has
disconnected.
The WebSocket implementation detects disconnected clients
immediately
and other HTTP servers (e.g. node) seem to be able to do this. What
is it about the Servlet async support that prevents it from knowing
when a client has disconnected?
It would mean having to ditch the BIO connector / or not being able
to pass the TCK (assuming the TCK tested this) when using the BIO
connector.
I guess this goes back to the previous question about whether there is an
explicit requirement and therefore test. Why would a TCK test explicitly check
that disconnects are not communicated to AsyncListeners? Or is it a more
indirect consequence of some other requirement?
My point was that if a disconnect event was added to the spec then the
BIO connector could never be spec compliant.
On reflection, it might not be that bad. The event could be fired just
not when the client disconnects. It would have to wait until an attempt
was made to read from / write to the socket.
Mark
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