Re: conneg considered harmful

...and just a couple more notes.  The last few updates to the Httpbis spec
added some clarification to the subject including these paragraphs.


Proactive negotiation has serious disadvantages:

   o  It is impossible for the server to accurately determine what might
      be "best" for any given user, since that would require complete
      knowledge of both the capabilities of the user agent and the
      intended use for the response (e.g., does the user want to view it
      on screen or print it on paper?);

   o  Having the user agent describe its capabilities in every request
      can be both very inefficient (given that only a small percentage
      of responses have multiple representations) and a potential risk
      to the user's privacy;

   o  It complicates the implementation of an origin server and the
      algorithms for generating responses to a request; and,

   o  It limits the reusability of responses for shared caching.


http://tools.ietf.org/html/draft-ietf-httpbis-p2-semantics-22#page-18

In is also interesting to note that Fielding is working on a ID that
describes a replacement for the vary header that solves some of the issues
relating to caching negotiated responses.
http://tools.ietf.org/html/draft-fielding-http-key-02


Darrel


On Fri, Jun 7, 2013 at 8:39 AM, Darrel Miller <[email protected]>wrote:

> For the record, here is a link [1] to Larry Masinter's apology for pushing
> accept header based conneg and his suggestion that it be deprecated.  It is
> sad that this email is from 2006 and yet here we are still...
>
>  Darrel
>
> [1] http://www.alvestrand.no/pipermail/ietf-types/2006-April/001707.html
>