Re: Using server-driven negotiation

On Wed, 5 Dec 2007, Adrien de Croy wrote:

>
> My 2c on the draft.

Thanks
>
> There is also considerable discussion on cache control implications and the 
> Vary tag.  I'm struggling to see where something that varies by geographic 
> location would be otherwise invariant (i.e. not vary on time, or other 
> factors which are currently in the control of the server).  For instance the

I'm not really suggesting that these usage cases would be cacheable, I 
just wanted to do it "right" so that incorrect cached responses would not 
be returned. We also specified a country or region code that is more 
likely to give cacheable pages than a numeric position, and Vary seems a 
better way than just setting Cache-Control: no-cache.

> There are technologies already that can use a browser and CGI to transfer the 
> requisite information about location without using HTTP headers.  You can use 
> Ajax to asynchronously POST location information to a script (i.e. to track 
> moving hosts).  Also, wherever there is user-input required to define 
> location, this could just as easily be in a form to post rather than in a 
> custom configuration dialog in a browser (that would then require browser 
> vendor support).

One of the authors has a module for mobile IE to take a GPS location and 
add it to each request, while I was playing with an HTTP proxy that does 
something similar. So the user isn't entering a position manually for 
each request, they are just browsing normally and the server is serving 
up location-dependant advertisements, or maps, or something.
I'm not sufficiently familiar with AJAX to see how this could be done 
without a user interaction.


>
> I'd also caution against using location as a means of selecting a language,

I didn't mean it like that; I mentioned language purely as an example of
current server-based negotiation.


> If you really want to convey this information in a header, have you 
> considered using an X- header?

That would work. As in X-xxxx: value, as opposed to registering a new 
formal header ?
I didn't see it in 2616.



-- 
Andrew Daviel, TRIUMF, Canada