Serving Documents Based on Language Preference
The Apache Web Server has the ability to look at the language preference
specified by a browser client and return the content of different files
depending on that preference. This ability, termed "language content negotiation",
is a simple yet very powerful feature of the Apache server that is not often
used.
There are essentially two approaches to content negotiation. The first
uses a "variants" file (or a "var" file) which essentially lists document
resources file by file and identifies them with a specific language. This
may be convenient for small sites or if you only want to provide language
typing for an entry page of a web site (which would then explicitly link
to web content authored in different languages). The second approach uses
file extensions (just like MIME types) to associate a file with a language.
Please find below a list of the steps necessary to configure the web
services on your Virtual Server to perform language content negotiation
by file extension. More information about configuring language content
negotiation on a file by file basis can be found by reading the reference
documents included at the bottom of this page.
- Add language type definitions to your web server configuration file
Using whatever method you find convenient, edit the ~/www/conf/httpd.conf on your
Virtual Private Server or the ~/www/conf/srm.conf file, if you VPS was configured before
Dec. 8, 1998) and add language definitions using the AddLanguage directive. For
example, add the following lines to your httpd.conf or srm.conf file:
AddLanguage en .en
AddLanguage es .es
AddLanguage fr .fr
AddLanguage de .de
AddLanguage it .it
AddLanguage jp .jp
Basically, this will associate the file extensions, .en .es .fr .de .it .jp, with the
corresponding language abbreviations, en es fr de it and jp. The abbreviations are pre-defined
and can be located in any of the latest generations of browser clients. For example, in Netscape
4.x they are found in "Edit->Preferences->smalltextator->Language->Add(button)". In MSIE 4.x they
are found in "View->Internet Options->General(tab)->Languages(button)->Add(button)".
- Add language priority definition to your web server configuration file
Using whatever method you find convenient, edit the ~/www/conf/httpd.conf file on your
VPS (or the ~/www/conf/srm.conf file, if you Virtual Server was configured before Dec.
8, 1998) and and add a language priority definition using the LanguagePriority directive. For
example, add the following line to your httpd.conf or srm.conf file:
LanguagePriority en es fr de
The language priority directive allows you to give precedence to some languages in case of a
"tie" during content negotiation or if the browser client does not specify a language priority
(older browsers). Just list the languages in decreasing order of preference.
- Modify the Options definition for your htdocs area to include "MultiViews"
Using whatever method you find convenient, edit the file access.conf (located in your ~/www/conf
directory) and add the option "MultiViews" to the Options directive that is part of your htdocs
Directory definition. For example, your Options line may look something like this:
Options Indexes FollowSymLinks MultiViews
The "MultiViews" option can also be added to the "Options" definition in .htaccess files.
That's it! Now you will need to author content and upload it to your
Virtual Server using appropriate extensions. For example, you would create
"index.html.en", "index.html.es", "index.html.fr", etc. instead of an
"index.html". When the browser client requests "index.html", the server
will analyze the language preference of the browser client and serve the
appropriate "index.html.*" file seamlessly and transparently.
There is at least one snag. If the language preference the browser submits
does match any of the type definitions on your server and documents you
have authored. The server will return a 406 error (i.e. the resource was
found, but could not be delivered because the type of the resource is
incompatible with the acceptable types indicated by the accept
or accept-encoding headers sent to the server by the client).
So, for example, if a client will only accept Greek content (el) and nothing
else, but you have only authored content in English, Spanish, and German,
the client will receive a 406 error. It may be wise to capture the 406
errors with a custom ErrorDocument script.
References
Content Negotiation Explained
(Apache Week Feature)
Content Negotiation (Apache.Org
Documentation)
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