Re: [hybi] Payload only compression extension, again

Greg Wilkins <gregw@webtide.com> Tue, 01 March 2011 07:00 UTC

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From: Greg Wilkins <gregw@webtide.com>
To: Takeshi Yoshino <tyoshino@google.com>
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Subject: Re: [hybi] Payload only compression extension, again
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On 1 March 2011 01:51, Takeshi Yoshino <tyoshino@google.com> wrote:
> Hi,
> Seeing several people preferring payload only compression, I'd like to
> resume discussion on it.

+1

> Requirements
> - Each message must be able to be uncompressed immediately

+1

> - Want not to mess up dictionary by compressing incompressible messages

Is that to say that you don't want to compress fragments?
I'm cautious about this as we don't want to have to buffer up all
fragments before we can decompress.

> - Want to maintain the compression state (LZ77 sliding window and Huffman
> table)

+1, although it might be good to have this as an extension option that
can be turned off.

> - Want to keep separate dictionaries for messages with different
> characteristics
> -- Case 1: Binary and text mixed
> -- Case 2: Short and long mixed
> -- Case 3: Application data in data frame and control frame may have
> different characteristics

-1 too complex.

I think that eventually MUX will be available that will keep different
types of messages in different channels.
Until that time, I expect to see very little mixed usage on WS
connections as each usage will just open up a fresh connection.



> --- Apply DEFLATE only to data frame (Is it worth including control frame?)

+1

control frames should be in the clear, so that they can be considered
and handled without the need to track extension or extension state.


cheers