Re: [hybi] Clarify the role of closing handshake

[Takeshi Yoshino <[e-mail]>]

In case you missed this part of my post citing Ian's thought.

http://www.ietf.org/mail-archive/web/hybi/current/msg01526.html

<http://www.ietf.org/mail-archive/web/hybi/current/msg01526.html>
>
> I think the net result is that ideally .close() should map to sending a
> FIN, aka using shutdown(SHUT_WR). Unfortunately this is not always
> possible -- people cited numerous examples of cases where we can't rely on
> TCP semantics in practice -- so we probably want to simulate this at the
> WebSocket layer or the application layer. Since the JS API exposes a
> .close() method, we should probably expose it at the WebSocket layer.


What do you think about this? I think it's nice to put your method just for
implementor's information together with Gabriel's idea in case we decide to
adopt Gabriel's idea, but reluctant to put it as mandatory protocol because
of this.

Takeshi


On Tue, Feb 15, 2011 at 16:10, <[e-mail]> wrote:

>
> Typo correction: The "SHOULD" in my text need to be "MUST" because both
> endpoints
> communicate using EoS in the proposed close handshake:
>
> (1) The endpoint MUST close write channel of the TCP connection
>    immediately after Close message is sent. (e.g. shutdown(SHUT_WR))
>
>
> (2) After both sending and receiving a Close message, both endpoints
>
>    MUST wait for EoS(End of Stream; i.e. recv() returning 0) before
>    closing TCP socket and discard any data received after the Close
>
>    message.
>
> (3) After both sending and receiving a Close message and the endpoint
>    has detected EoS, then the WebSocket connection is said to have been
>    closed _cleanly_.
>
> --
> Yutaka Takeda - US R&D Sony Computer Entertainment, Inc.
> Office: 650 655 7484   Fax: [phone]
>
>
>
>  *Yutaka Takeda/R&D/SCEA@Playstation*
> Sent by: [e-mail]
>
> 02/15/2011 04:05 PM
>   To
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> cc
> [e-mail]
> Subject
> Re: [hybi] Clarify the role of closing handshake
>
>
>
>
>
> Ian Fette (イアンフェッティ) <[e-mail]> wrote on 02/15/2011 02:27:58 PM:
>
> > What I'm currently looking at is this: (comments welcome)
> >
> >          <t>The Close message contains an opcode of 0x01.</t>
> >           <t>The Close message contains no body (the body has zero
> > length).</t>
> >           <t>The application MUST NOT send any more data messages
> > after sending
> >           a close message.</t>
> >           <t>If an endpoint receives a Close message and that endpoint
> did not
> >           previously send a Close message, the endpoint MUST send a Close
> >           message in response. It SHOULD do so as soon as is practical.
> >           </t>
> >           <t>After both sending and receiving a close message, an
> endpoint
> >           considers the websocket connection closed, and
> >           SHOULD close the underlying TCP connection.</t>
> >           <t>If a client and server both send a Close message at thesame
> time,
> >           both endpoints will have sent and received a Close messageand
> should
> >           consider the websocket connection closed and close the
> underlying
> >           TCP connection.</t>
>
> I would replace corresponding texts with something along the line of the
> following for more completeness:
>
> (1) The endpoint SHOULD close write channel of the TCP connection
>    immediately after Close message is sent. (e.g. shutdown(SHUT_WR))
>
> (2) After both sending and receiving a Close message, both endpoints
>    SHOULD wait for EoS(End of Stream; i.e. recv() returning 0) before
>    closing TCP socket and discard any data received after the Close
>    message.
>
> (3) After both sending and receiving a Close message and the endpoint
>    has detected EoS, then the WebSocket connection is said to have been
>    closed _cleanly_.
>
> Justification:
> - (1) is to ensure that no more data will be written to the
>  underlying TCP socket after the Close message, and to indicate
>  that sender has reached the EoS at TCP level.
> - (2) is to prevent the endpoint from generating spurious RST
>  due to a bug at the remote endpoint injecting data after Close frame.
> - Presence of Close frame helps intermediaries to detect normal closure
>  of WebSocket connection.
>
> Best.
>
> - Yutaka _______________________________________________
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