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Re: [hybi] Is it important to know frame length at the start of frame? (was: Re: Discontinuation of mux ...)

Takeshi Yoshino <tyoshino@google.com> Thu, 13 February 2014 04:14 UTC

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From: Takeshi Yoshino <tyoshino@google.com>
Date: Thu, 13 Feb 2014 13:14:18 +0900
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To: Peter Thorson <webmaster@zaphoyd.com>
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Subject: Re: [hybi] Is it important to know frame length at the start of frame? (was: Re: Discontinuation of mux ...)
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On Thu, Feb 13, 2014 at 1:25 AM, Peter Thorson <webmaster@zaphoyd.com>wrote:

> > PING - not necessary while we are writing data. If peer is
>  > unresponsive, we'll learn that from TCP layer.
>
> It does provide some separation of concerns and the ability to do things
> like measure RTT during a long message.


There can be an intermediary which silently terminates TCP and relay
WebSocket traffic. In such case, app level request for pong is useful for
liveness detection. The intermediary still can relay unresponsiveness of
the peer endpoint to the endpoint (by disconnecting the TCP connection) and
maybe it needs to do so due to limited buffer. So, I admit that this
argument is not so strong support for necessity of PING.

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