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Re: [hybi] Payload only compression extension, again

Greg Wilkins <gregw@intalio.com> Mon, 02 May 2011 09:27 UTC

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Date: Mon, 02 May 2011 19:27:31 +1000
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From: Greg Wilkins <gregw@intalio.com>
To: Patrick McManus <pmcmanus@mozilla.com>
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Subject: Re: [hybi] Payload only compression extension, again
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In jetty trunk I have an implementation of an extension I've called
x-deflate-frame for now.

It uses 1 reserve bit to indicate if the payload is compressed.
If the payload is compressed, then it is sent as:

    uncompressed-length  deflated-data

The uncompressed-length is encoded in the same format as the websocket
frame length.  The uncompressed length is sent so that a buffer may be
allocated before starting to inflate the data.

The extension supports a minLength parameter (default 64) and will not
attempt to compress payloads that are smaller than that length.

When compressing the data, if the combined uncompressed-length and
deflated-data is longer than the original data, then the original data
frame is sent instead.

Currently I'm just using the standard java Inflater/Deflater  gzip
classes with a reset between frames.  Not exactly sure what that means
with regards to the algorithm details that Takeshi has specified, but
I think they are close.

cheers

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