HTTP compression: Difference between revisions

Revision as of 22:47, 6 March 2023

Revision as of 21:18, 5 April 2023

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*[[rsync]]<ref>{{cite web |title=rproxy: Protocol Definition for HTTP rsync Encoding |url=https://rproxy.samba.org/doc/protocol/protocol.html |website=rproxy.samba.org}}</ref> - [[Delta_encoding#Delta_encoding_in_HTTP|delta encoding in HTTP]], implemented by a pair of ''rproxy'' proxies.

*xpress - Microsoft compression protocol used by Windows&nbsp;8 and later for Windows Store application updates. [[LZ77_and_LZ78#LZ77|LZ77]]-based compression optionally using a Huffman encoding.<ref>{{cite web|url=https://msdn.microsoft.com/en-us/library/Hh554002.aspx|title=[MS-XCA]: Xpress Compression Algorithm|access-date=29 August 2015}}</ref>

*[[XZ Utils|xz]] - LZMA2-based content compression, supported by a non-official Firefox patch;<ref>{{cite web|url=https://wiki.mozilla.org/LZMA2_Compression|title=LZMA2 Compression - MozillaWiki|access-date=18 April 2014}}</ref> and fully implemented in mget since 2013-12-31.<ref>{{cite web|url=https://github.com/rockdaboot/mget|title=mget GitHub project page|website=[[GitHub]] |access-date=6 January 2017}}</ref>

==Servers that support HTTP compression==

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==Problems preventing the use of HTTP compression==

A 2009 article by Google engineers Arvind Jain and Jason Glasgow states that more than 99 person-years are wasted<ref name="google-use-compression">{{cite web|url=https://developers.google.com/speed/articles/use-compression|title=Use compression to make the web faster|access-date=22 May 2013|publisher=Google DevelopersInc.}}</ref> daily due to increase in page load time when users do not receive compressed content. This occurs when anti-virus software interferes with connections to force them to be uncompressed, where proxies are used (with overcautious web browsers), where servers are misconfigured, and where browser bugs stop compression being used. Internet Explorer 6, which drops to HTTP 1.0 (without features like compression or pipelining) when behind a proxy&nbsp;– a common configuration in corporate environments&nbsp;– was the mainstream browser most prone to failing back to uncompressed HTTP.<ref name="google-use-compression" />

Another problem found while deploying HTTP compression on large scale is due to the '''deflate''' encoding definition: while HTTP 1.1 defines the '''deflate''' encoding as data compressed with deflate (RFC 1951) inside a [[zlib]] formatted stream (RFC 1950), Microsoft server and client products historically implemented it as a "raw" deflated stream,<ref>{{cite web|url=https://stackoverflow.com/questions/9170338/why-are-major-web-sites-using-gzip/9186091#9186091|title=deflate - Why are major web sites using gzip?|publisher=Stack Overflow|access-date=18 April 2014}}</ref> making its deployment unreliable.<ref>{{cite web|url=http://www.vervestudios.co/projects/compression-tests/|title=Compression Tests: About|publisher=Verve Studios|archive-url=https://web.archive.org/web/20150102111552/http://www.vervestudios.co/projects/compression-tests/|archive-date=2 January 2015|access-date=18 April 2014}}</ref><ref>{{cite web|url=http://zoompf.com/blog/2012/02/lose-the-wait-http-compression|title=Lose the wait: HTTP Compression|publisher=Zoompf Web Performance|access-date=18 April 2014}}</ref> For this reason, some software, including the Apache HTTP Server, only implement '''gzip''' encoding.