title
	CNP compression (draft)


content
	section Overview
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			This draft aims to specify the protocol for compressing body data of CNP requests and responses.


	section Syntax
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			A new request and response parameter, ``compression``, would be defined:

		raw cnp
			compression={algorithm}

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			Where ``{algorithm}`` is the compression algorithm used.

			A request parameter, ``accept_compression``, would be defined:

		raw cnp
			accept_compression={algorithms}

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			Where ``{algorithms}`` is a comma-separated list of compression algorithms (e.g. ``accept_compression=lz4,gzip,deflate``) with decreasing priority.


	section Functionality
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			The body data of the message is compressed using the specified algorithm.

			If the ``length`` parameter is to be set, it must contain the length of the data after compression, not before it.

			The client should only use the standard compression algorithms or ones provided by the server in something like the @@/draft/old/cnp-select/ options selector@@.

			The server may use any compression algorithm provided in the ``accept_compression`` request parameter, with the ones towards the start of the list being preferred; if that parameter is absent, the server must not use compression.


	section Algorithms
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			While custom compression algorithms may be used, all server implementations are expected to support the following ones:

		list
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				``gzip``: A @@https://en.wikipedia.org/wiki/Gzip gzip@@ (@@https://www.ietf.org/rfc/rfc1952.txt RFC 1952@@) stream using the DEFLATE algorithm.
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				``zlib``: A @@https://en.wikipedia.org/wiki/Zlib zlib@@ (@@https://www.ietf.org/rfc/rfc1950.txt RFC 1950@@) stream using the DEFLATE algorithm.
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				``deflate``: A @@https://en.wikipedia.org/wiki/Deflate DEFLATE@@ (@@https://www.ietf.org/rfc/rfc1951.txt RFC 1951@@) data stream (**not** the zlib file format).


	section Possible changes
		list
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				Remove all but ``gzip`` algorithms from the default ones, since they're all basically DEFLATE (plus maybe checksum).
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				Consider algorithms like @@https://en.wikipedia.org/wiki/Brotli Brotli@@.


site
	draft
		cnp-compression

links
	/spec/  Specifications
	/doc/   Documents
	/draft/ Drafts
	/lib/   Libraries
	/util/  Tools and utilities