mod_gzip is an external extension module for the

Apache HTTP Server The Apache HTTP Server ( ) is a free and open-source cross-platform web server software, released under the terms of Apache License 2.0. Apache is developed and maintained by an open community of developers under the auspices of the Apache So ...

v1 and v2. It allows using the

Gzip gzip is a file format and a software application used for file compression and decompression. The program was created by Jean-loup Gailly and Mark Adler as a free software replacement for the compress program used in early Unix systems, and in ...

compression method for a significant reduction of the volume of web page content served over the

HTTP The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, ...

protocol. mod_gzip can be compiled into Apache as either a static or dynamic module.

Compatibility

It is possible to check a server to see if it is sending out compressed data, and compression compatibility of a browser for exampl
here
When textual content is compressed using mod_gzip, it should maintain its

MIME-type A media type (also known as a MIME type) is a two-part identifier for file formats and format contents transmitted on the Internet. The Internet Assigned Numbers Authority (IANA) is the official authority for the standardization and publication o ...

, 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. 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 mod_deflate is an optional module for the Apache HTTP Server, Apache v2.0 and later. It is based on Deflate lossless data compression algorithm that uses a combination of the LZ77 algorithm and Huffman coding. This module provides the DEFLATE ou ...

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. 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 PHP is a general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementation is now produced by The PHP Group ...

similar effect achievable for the output of PHP scripts with: * th
ob_gzhandler()
and th
gzencode()
functions; * zlib.output_compression option in the php.ini file.

CherryPy CherryPy is an object-oriented web application framework using the Python programming language. It is designed for rapid development of web applications by wrapping the HTTP protocol but stays at a low level and does not offer much more than what ...

offers the ''Gzip filter'', which uses th
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 Kevin Kiley and Konstantin Balashow in autumn 2000, documented by Michael Schröpl, published b
Remote Communications Inc.
(RCI). RCI was purchased by HyperSpace Communications, RCI released the code into the public domain.
/ref> 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.

External links

Original homepage
of mod_gzip. * Starting with version 1.3.19.2a mod_gzip has found
new home
on SourceForge.

Notes