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Re: [hybi] Payload only compression extension, again

John Tamplin <jat@google.com> Mon, 02 May 2011 22:02 UTC

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From: John Tamplin <jat@google.com>
Date: Mon, 02 May 2011 18:02:10 -0400
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To: Greg Wilkins <gregw@intalio.com>
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Cc: "hybi@ietf.org" <hybi@ietf.org>, Patrick McManus <pmcmanus@mozilla.com>
Subject: Re: [hybi] Payload only compression extension, again
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On Mon, May 2, 2011 at 5:59 PM, Greg Wilkins <gregw@intalio.com> wrote:

> > See the compression experiments I posted last May - if you don't maintain
> > compression state between frames, then you lose most of the benefit of
> > compression.  Being able to send uncompressed frames cheaply avoids the
> cost
> > of this, but doesn't fix not getting the benefit of compression.
> > Unfortunately, Java's default deflate implementation doesn't allow this,
> as
> > you need to flush out the compressed bits at the end of a frame (though
> you
> > can play tricks with changing the compression level to 0 and back, but
> that
> > seems non-portable).  I believe you can do it with jzlib though.
>
> Yes, the java std lib does appear lacking in this regard.  As I said,
> I'm just using it for prototyping and don't think that it's
> deficiencies should greatly influence any effort to standardise such
> an extension - specially if better libraries are available (argh! they
> have license clashes and eclipse IP issues... still not a problem for
> this group).
>

My point was I see little value in having a compression extension which
starts the compression state afresh with every frame, as on real-world
applications this gives poor performance.

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

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