Re: [hybi] Masking only Payload/Extension Data

John Tamplin <jat@google.com> Wed, 09 March 2011 20:39 UTC

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From: John Tamplin <jat@google.com>
Date: Wed, 09 Mar 2011 15:40:06 -0500
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To: Greg Wilkins <gregw@webtide.com>
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Cc: Hybi <hybi@ietf.org>, Yutaka_Takeda@playstation.sony.com
Subject: Re: [hybi] Masking only Payload/Extension Data
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On Wed, Mar 9, 2011 at 3:33 PM, Greg Wilkins <gregw@webtide.com> wrote:

> So I think masking is a perfect exemplar for the use of a reserve bit.
>  If it can't get over the line, then I doubt any usage can.
>

Assuming the browser vendors stick to the requirement that client-side
masking is mandatory, then every single MASKED bit will be set on the
client->server side, and either all will be set or all will be cleared on
the server side of the connection.  The receiver knows without a doubt the
state of masking for the next frame it will receive (and should drop the
connection if that expectation isn't met).  That doesn't seem like a useful
candidate to have something that doesn't change in every single frame, when
the sole benefit of it is for debugging.

Compare that to allocating a bit to show a frame is compressed -- we
certainly know that some messages will be compressible (text), while others
won't (images, audio, pre-compressed data, etc).  The receiver has no way of
knowing ahead of time which sort of message will next be sent, so it makes
sense to allocate a bit to say whether this frame was compressed or not.

-- 
John A. Tamplin
Software Engineer (GWT), Google