Comments on: Advanced HTTP Redirection http://www.askapache.com/seo/advanced-http-redirection.html Advanced Web Development Thu, 18 Mar 2010 14:15:10 +0000 hourly 1 By: AskApache http://www.askapache.com/seo/advanced-http-redirection.html#comment-67971 AskApache Tue, 03 Mar 2009 00:29:24 +0000 http://www.askapache.com/seo/advanced-http-redirection.html#comment-67971 I've used <a href="http://www.askapache.com/htaccess/htaccess-fresh.html#modrewrite3" rel="nofollow">mod_rewrite to accomplish this instead of using 300</a> HTTP Headers by checking the request headers, mostly the Accept-Language, Accept, and Accept Charset headers. But the way that it is meant to be used is basically if your server has 3 versions of the file rfc2616: rfc2616.txt rfc2616.pdf rfc2616.png Then you set up your server to using one form of negotion or another, to respond to requests for the url /rfc2616 with a 300 Multiple Choices response header that includes the links to all 3 different versions, which lets the user-agent decide which one they want. Agent-driven Negotiation <blockquote cite="http://www.w3.org/Protocols/rfc2616/rfc2616-sec12.html#sec12.1"> With agent-driven negotiation, selection of the best representation for a response is performed by the user agent after receiving an initial response from the origin server. Selection is based on a list of the available representations of the response included within the header fields or entity-body of the initial response, with each representation identified by its own URI. Selection from among the representations may be performed automatically (if the user agent is capable of doing so) or manually by the user selecting from a generated (possibly hypertext) menu. Agent-driven negotiation is advantageous when the response would vary over commonly-used dimensions (such as type, language, or encoding), when the origin server is unable to determine a user agent's capabilities from examining the request, and generally when public caches are used to distribute server load and reduce network usage. Agent-driven negotiation suffers from the disadvantage of needing a second request to obtain the best alternate representation. This second request is only efficient when caching is used. In addition, this specification does not define any mechanism for supporting automatic selection, though it also does not prevent any such mechanism from being developed as an extension and used within HTTP/1.1. HTTP/1.1 defines the 300 (Multiple Choices) and 406 (Not Acceptable) status codes for enabling agent-driven negotiation when the server is unwilling or unable to provide a varying response using server-driven negotiation. </blockquote> I’ve used mod_rewrite to accomplish this instead of using 300 HTTP Headers by checking the request headers, mostly the Accept-Language, Accept, and Accept Charset headers. But the way that it is meant to be used is basically if your server has 3 versions of the file rfc2616:

rfc2616.txt
rfc2616.pdf
rfc2616.png

Then you set up your server to using one form of negotion or another, to respond to requests for the url /rfc2616 with a 300 Multiple Choices response header that includes the links to all 3 different versions, which lets the user-agent decide which one they want.

Agent-driven Negotiation

With agent-driven negotiation, selection of the best representation for a response is performed by the user agent after receiving an initial response from the origin server. Selection is based on a list of the available representations of the response included within the header fields or entity-body of the initial response, with each representation identified by its own URI. Selection from among the representations may be performed automatically (if the user agent is capable of doing so) or manually by the user selecting from a generated (possibly hypertext) menu.

Agent-driven negotiation is advantageous when the response would vary over commonly-used dimensions (such as type, language, or encoding), when the origin server is unable to determine a user agent’s capabilities from examining the request, and generally when public caches are used to distribute server load and reduce network usage.

Agent-driven negotiation suffers from the disadvantage of needing a second request to obtain the best alternate representation. This second request is only efficient when caching is used. In addition, this specification does not define any mechanism for supporting automatic selection, though it also does not prevent any such mechanism from being developed as an extension and used within HTTP/1.1.

HTTP/1.1 defines the 300 (Multiple Choices) and 406 (Not Acceptable) status codes for enabling agent-driven negotiation when the server is unwilling or unable to provide a varying response using server-driven negotiation.

]]> By: John S. Britsios (aka Webnauts) http://www.askapache.com/seo/advanced-http-redirection.html#comment-67952 John S. Britsios (aka Webnauts) Mon, 02 Mar 2009 19:46:59 +0000 http://www.askapache.com/seo/advanced-http-redirection.html#comment-67952 You mentioned about the 300 HTTP Headers: <blockquote> Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice MAY be performed automatically. However, this specification does not define any standard for such automatic selection.</blockquote> Can you explain how can this be implemented? You mentioned about the 300 HTTP Headers:

Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice MAY be performed automatically. However, this specification does not define any standard for such automatic selection.

Can you explain how can this be implemented?

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