mod_gzip
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mod_gzip is an external extension module for the Apache HTTP Server v1 and v2.
It allows using the Gzip compression method for a significant reduction of the volume of web page content served over the HTTP protocol.
mod_gzip can be compiled into Apache as either a static or dynamic module.
Contents
Compatibility
You can check a server to see if it is sending out compressed data, and compression compatibility of your browser for example here.
When textual content is compressed using mod_gzip, it should maintain its MIME-type, according to their recommended media type:
- HTML: text/html
- XHTML: application/xhtml+xml
- CSS: text/css
- JavaScript: application/x-javascript
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.[1]
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.
Some alternatives
The mod_deflate 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.[2] Starting with Apache 2.0.45, the compression level of mod_deflate is configurable using the DeflateCompressionLevel directive, so this difference disappeared.
A mod_gz module was independently developed by Ian Holsman. This module implements a gzip compression filter 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.
In PHP similar effect achievable for the output of PHP scripts with:
- the ob_gzhandler() and the gzencode() functions;
- zlib.output_compression option in the php.ini file.
CherryPy offers the Gzip filter,[3] which uses the zlib module of Python standard library.
License
The mod_gzip module licensed with Apache License.
History
Module level content compression for Apache started with mod_gzip, written by Michael Schröpl in autumn 2000,[4][5] published by Remote Communications Inc. (RCI).[6] RCI was purchased by HyperSpace Communications, RCI released the code into the public domain.[7]
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.
See also
- mod_deflate
- HTTP compression
- Some general purpose Apache modules
- Some programming language interfaces for Apache
External links
- Original homepage of mod_gzip.
- Starting with version 1.3.19.2a mod_gzip has found a new home on SourceForge.
