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RE: Striving for Compromise (Consensus?)

From: <K.Morgan@iaea.org>
Date: Fri, 11 Jul 2014 09:41:31 +0000
To: <jpinner@twitter.com>, <ietf-http-wg@w3.org>
Message-ID: <0356EBBE092D394F9291DA01E8D28EC201187ED7E4@SEM002PD.sg.iaea.org>
On Friday,11 July 2014 09:32, jpinner@twitter.com wrote:

> How do people feel about the following compromise:

It eliminates both purposes of the 'Greg et al' proposal:
  a) Eliminate the CONTINUATION ugliness (complexity, processing, etc.), and
  b) add bits & settings for tuning frame lengths.

> 1) Increase frame size to 16-bits.

I don't know how this could be claimed as a good idea without also having the SETTINGS_HEADER_SIZE & SETTINGS_FRAME_SIZE setting.  Roberto, Patrick, etc. have repeatedly said that 16K is the 'optimal' frame size for multiplexing on today's networks.  Moving to 16 bits without a setting means everybody will use 64K.  Remember, in the 'Greg et al' proposal the default frame size is still 16K (actually it's literally one better - it's 16K instead of 16K-1!).

It's also terribly short-sighted to not have any space for expansion.  At the very least you should keep 1 reserved bit so you can do the ugly "jumbo frame" hack later when you figure out you want bigger frame sizes.

> 2) Remove reference set from HPACK allowing for "streaming" decoding.

This is a good idea.

> 3) Requiring that all ":"-headers appear first.

This is also a good idea.

> 4) Only allowing CONTINUATION if the previous frame is 2^16-1 bytes.

See Roberto's thread "Fragmentation for headers: why jumbo != continuation" [1] for reasons why he thinks this is a bad idea.

> 5) Allowing interleaving of CONTINUATION frames with other frames.

Admittedly better than the status quo, but still not entirely clear why this is necessary. i.e. why not 1*HEADERS instead?

[1] http://lists.w3.org/Archives/Public/ietf-http-wg/2014JulSep/0687.html

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Received on Friday, 11 July 2014 09:42:29 UTC

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