[hybi] Max frame size

Francis Brosnan Blázquez <francis@aspl.es> Wed, 22 June 2011 05:34 UTC

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From: Francis Brosnan =?ISO-8859-1?Q?Bl=E1zquez?= <francis@aspl.es>
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Date: Wed, 22 Jun 2011 07:34:20 +0200
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Subject: [hybi] Max frame size
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Current frame design allows to send a very big single frame size (63
bits). In terms of memory a websocket server will have problems with
this because he must buffer all content until he can deliver the entire
message to the app level (assuming message based API).

I think we need a way for servers (and possibly clients) to notify each
other which is the max frame size each part is willing to accept so each
site administrator can configure this according to its resources,
application type, number of connections, etc.

I think a simple header notified at the websocket handshake will provide
this valuable control to each party:

   Max-Frame-Size: 4096

This will cause each party to fragment application level messages if it
is found bigger than Max-Frame-Size.

In the same direction, if not provided Max-Frame-Size, it looks
reasonable to assume a default value for this header. Again, 4096 bytes
looks like a good value.

What do you think?