This module provides for content negotiation.
Status: Base
Source File: mod_negotiation.c
Module Identifier: negotiation_module
Content negotiation, or more accurately content selection, is the selection of the document that best matches the clients capabilities, from one of several available documents. There are two implementations of this.
type-map
) which explicitly lists the files containing the variants.: DefaultLanguage, AddEncoding, AddLanguage, AddType, and Options.
A type map has the same format as RFC822 mail headers. It contains document descriptions separated by blank lines, with lines beginning with a hash character ('#') treated as comments. A document description consists of several header records; records may be continued on multiple lines if the continuation lines start with spaces. The leading space will be deleted and the lines concatenated. A header record consists of a keyword name, which always ends in a colon, followed by a value. Whitespace is allowed between the header name and value, and between the tokens of value. The headers allowed are:
x-compress
for compress'd files, and x-gzip
for gzip'd files. The x-
prefix is ignored for encoding comparisons.en
, meaning English.name=value
. Common parameters include:
text/html
this defaults to 2, otherwise 0.Content-Type: image/jpeg; qs=0.8
A MultiViews search is enabled by the MultiViews Option. If the server receives a request for /some/dir/foo
and /some/dir/foo
does not exist, then the server reads the directory looking for all files named foo.*
, and effectively fakes up a type map which names all those files, assigning them the same media types and content-encodings it would have if the client had asked for one of them by name. It then chooses the best match to the client's requirements, and returns that document.
CacheNegotiatedDocs
Context: server config
Status: Base
Module: mod_negotiation
Compatibility: CacheNegotiatedDocs is only available in Apache 1.1 and later.
If set, this directive allows content-negotiated documents to be cached by proxy servers. This could mean that clients behind those proxys could retrieve versions of the documents that are not the best match for their abilities, but it will make caching more efficient.
This directive only applies to requests which come from HTTP/1.0 browsers. HTTP/1.1 provides much better control over the caching of negotiated documents, and this directive has no effect in responses to HTTP/1.1 requests.
LanguagePriority MIME-lang [MIME-lang] ...
Context: server config, virtual host, directory, .htaccess
Override: FileInfo
Status: Base
Module: mod_negotiation
The LanguagePriority sets the precedence of language variants for the case where the client does not express a preference, when handling a MultiViews request. The list of MIME-lang are in order of decreasing preference. Example:
LanguagePriority en fr de
For a request for foo.html
, where foo.html.fr
and foo.html.de
both existed, but the browser did not express a language preference, then foo.html.fr
would be returned.
Note that this directive only has an effect if a 'best' language cannot be determined by any other means. Correctly implemented HTTP/1.1 requests will mean this directive has no effect.
See also: DefaultLanguage and AddLanguage