Client close notification

[glassfishrobot]

There is no notification event for client close.
Is it possible to add AsyncListener#onClose() when the client is disconnected ? This will be
useful for long running connections like server-sent events connection.

On the other hand, SE socket API itself doesn't provide that option. So there may be no way to get client close notification when there is no pending i/o.

[glassfishrobot]

@glassfishrobot Commented
Reported by jitu

[glassfishrobot]

@glassfishrobot Commented
@mpotociar said:
onDisconnect(...) would be a better name IMO. Also, if that's not possible due to the lack of JavaSE Socket API, should it be clarified that onError(...) could be used for that purpose?

[glassfishrobot]

@glassfishrobot Commented
@shingwaichan said:
There is no way to know when the socket is closed from SE API.

[glassfishrobot]

@glassfishrobot Commented
jfarcand said:
I disagree. Any NIO layer can detect when the underlying connection is getting closed. Look at Grizzly/Tomcat NIO/Netty, they all able to handle that case.

[glassfishrobot]

@glassfishrobot Commented
@shingwaichan said:
java.nio.channels.Channel#isOpen tests whether or not the channel is open.
So, we will revisit the issue.

[glassfishrobot]

@glassfishrobot Commented
ash2k said:
Because this feature is missing it is not possible to stop resource consuming computations on server if client disconnects. Please, see this ticket for example https://sourceforge.net/apps/trac/bigdata/ticket/694

[glassfishrobot]

@glassfishrobot Commented
rstoyanchev said:
Adding a link to a discussion on Tomcat's user list.

[glassfishrobot]

@glassfishrobot Commented
rstoyanchev said:
As one example of why this matters consider the SockJS protocol that provides HTTP fallback options for WebSocket.

The protocol does not define any client-side "close" frame. It expects the server will detect when the HTTP connection is closed and indeed a variety of server-side implementations in a range of languages (node, erlang, python, ruby) do.

A Java implementation – with Servlet 3 async for the long polling or HTTP streaming – however cannot detect when a client has gone away. This is a very fundamental, missing feature that puts Java Servlet-based implementations at a significant disadvantage.

[glassfishrobot]

@glassfishrobot Commented
This issue was imported from java.net JIRA SERVLET_SPEC-44

[glassfishrobot]

• Issue Imported From: https://github.com/javaee/servlet-spec/issues/44
• Original Issue Raised By:@glassfishrobot
• Original Issue Assigned To: @shingwaichan

[gregw]

I think such a new API is out of scope for 5.1... however we should clarify our existing APIs in similar circumstances such as clarifications of HTTP/2 behaviour with regards to async calls to onError etc. discussed in #256