This module is contained in the
mod_negotiation.c file, and
is compiled in by default. It provides for
content negotiation. Any document with
application/x-type-map will be processed by this 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.
- A type map (a file with the mime type
which explicitly lists the files containing the variants.
- A MultiViews search (enabled by the MultiViews
Option, where the server does an implicit
filename pattern match, and choose from amongst the results.
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 encoding of the file. Currently only two encodings are recognised
x-compress for compressed files, and
for gzipped files.
- The language of the variant, as an Internet standard language code, such
- The length of the file, in bytes. If this header is not present, then
the actual length of the file is used.
- The MIME media type of the document, with optional parameters.
parameters are separated from the media type and from one another by
semi-colons. Parameter syntax is name=value; allowed parameters are:
- the value is an integer, which specifies the version of the media type.
text/html this defaults to 2, otherwise 0.
- the value is a floating-point number with value between 0. and 1.
It indications the 'quality' of this variant.
Content-Type: image/jpeg; qs=0.8
- The path to the file containing this variant, relative to the map file.
A MultiViews search is enabled by the MultiViews
If the server receives a request for
/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.
Syntax: LanguagePriority mime-lang mime-lang...
Context: server config, virtual host, directory, .htaccess
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
For a request for
LanguagePriority en fr de
foo.html.de both existed, but the browser did not express
a language preference, then
foo.html.fr would be returned.