Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
mod_gzip
open-in-new
<h2 id="compatibility">Compatibility</h2> <p>It is possible to check a server to see if it is sending out compressed data, and compression compatibility of a browser for example <a href="http://www.whatsmyip.org/http_compression/">here</a>. </p><p>When textual content is compressed using mod_gzip, it should maintain its <a href="/facts/Internet_media_type/A31N5Fwj">MIME-type</a>, according to their recommended media type: </p> <ul><li>HTML: text/html</li> <li>XHTML: application/xhtml+xml</li> <li>CSS: text/css</li> <li>JavaScript: application/x-javascript</li></ul> <p>One of the earliest Apache 1.3 versions introduced some internal function for regular expression evaluation. This function is used by mod_gzip (for evaluating the filter rules), therefore mod_gzip would not work together with Apache 1.2.x or earlier versions.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p><p>Compatibility between Apache 1.3.x and mod_gzip 1.3.y is granted in general: the Apache 1.3 API doesn't change any more, mod_gzip would even work together with very old Apache 1.3 versions. </p> <h2 id="some-alternatives">Some alternatives</h2> <p>The <a href="/facts/Mod_deflate/2ms9k46x">mod_deflate</a> module is similar to mod_gzip, but usable only with Apache v2. Early versions of mod_deflate provided lesser amount of compression than mod_gzip.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Starting with Apache 2.0.45, the compression level of mod_deflate is configurable using the <i>DeflateCompressionLevel</i> directive, so this difference disappeared. </p><p>A mod_gz module was independently developed by Ian Holsman. This module implements a gzip compression <i>filter</i> for Apache 2.0, providing similar functionality to mod_gzip. One important difference between the two modules is that mod_gzip includes its own gzip implementation, whereas mod_gz relies on an external zlib library. </p><p>In <a href="/facts/PHP/vU6YRJX0">PHP</a> similar effect achievable for the output of PHP scripts with: </p> <ul><li>the <a href="http://php.net/manual/en/function.ob-gzhandler.php">ob_gzhandler()</a> and the <a href="http://php.net/manual/en/function.gzencode.php">gzencode()</a> functions;</li> <li>zlib.output_compression option in the php.ini file.</li></ul> <p><a href="/facts/CherryPy/PpTD1wU8">CherryPy</a> offers the <i>Gzip filter</i>,<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> which uses the <a href="https://web.archive.org/web/20100225005805/http://www.python.org/doc/2.5.2/lib/module-zlib.html">zlib module</a> of Python standard library. </p> <h2 id="license">License</h2> <p>The mod_gzip module licensed with <a href="/facts/Apache_License/5AeIjas8">Apache License</a>. </p> <h2 id="history">History</h2> <p>Module level content compression for Apache started with mod_gzip, written by Kevin Kiley and Konstantin Balashow<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> in autumn 2000, documented by Michael Schröpl,<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> published by <a href="http://remotecommunications.com">Remote Communications Inc.</a> (RCI).<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> RCI was purchased by HyperSpace Communications, RCI released the code into the public domain.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p><p>The developers of the Apache 2.0.x servers have included the mod_deflate module in the codebase for the server to perform a similar GZIP-encoding function. mod_gzip remained external extension module. </p> <h2 id="see-also">See also</h2> <ul> <li>Free and open-source software portal</li></ul> <ul><li><a href="/facts/Mod_deflate/2ms9k46x">mod_deflate</a></li> <li><a href="/facts/HTTP_compression/clfoMHvy">HTTP compression</a></li> <li><a href="/facts/Mod_ssl/L8jVRoUu">Some general purpose Apache modules</a></li> <li><a href="/facts/Mod_ssl/L8jVRoUu">Some programming language interfaces for Apache</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.schroepl.net/projekte/mod_gzip/">Original homepage</a> of mod_gzip.</li> <li>Starting with version 1.3.19.2a mod_gzip has found a <a href="http://sourceforge.net/projects/mod-gzip/">new home</a> on SourceForge.</li></ul> <h2 id="notes">Notes</h2> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>mod_gzip requires Apache 1.3+ <a href="http://schroepl.net/projekte/mod_gzip/versions.htm" target="_blank">http://schroepl.net/projekte/mod_gzip/versions.htm</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Comparison of mod_deflate and mod_gzip <a href="http://newestindustry.org/2006/10/03/compressing-web-output-using-mod_deflate-and-apache-20x-2/" target="_blank">http://newestindustry.org/2006/10/03/compressing-web-output-using-mod_deflate-and-apache-20x-2/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"CherryPy offers the Gzip filter". Archived from the original on 2005-02-12. Retrieved 2009-10-11. <a href="https://web.archive.org/web/20050212003622/http://www.cherrypy.org/wiki/GzipFilter" target="_blank">https://web.archive.org/web/20050212003622/http://www.cherrypy.org/wiki/GzipFilter</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Cranstone, Peter (2000-10-17). "WebReference Featured Interview". www.webreference.com. Retrieved 2017-07-02. <a href="http://www.webreference.com/interviews/petercranstone2.html" target="_blank">http://www.webreference.com/interviews/petercranstone2.html</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"mod_gzip written by Michael Schröpl". Archived from the original on 2008-09-17. Retrieved 2009-10-11. <a href="https://web.archive.org/web/20080917014155/http://www.linuxplanet.com/linuxplanet/tutorials/5461/2/" target="_blank">https://web.archive.org/web/20080917014155/http://www.linuxplanet.com/linuxplanet/tutorials/5461/2/</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>mod_gzip written in autumn 2000 <a href="http://schroepl.net/projekte/mod_gzip/" target="_blank">http://schroepl.net/projekte/mod_gzip/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>RCI had originally published mod_gzip <a href="http://schroepl.net/projekte/mod_gzip/" target="_blank">http://schroepl.net/projekte/mod_gzip/</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>RCI released the code into the public domain <a href="http://www.webreference.com/internet/software/servers/http/compression/2.html" target="_blank">http://www.webreference.com/internet/software/servers/http/compression/2.html</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> </ol>