Re: Updated Working Draft: Enabling Discovery Of Alternative Representations

T.V Raman schrieb:
> 
> 
> 
> Paul Libbrecht writes:
>  >  From reading such a document I get the impression that all negotiation 
>  > logic should be concentrated before a redirect in order for caches to be 
>  > enabled. Am I summarizing correctly ?
> 
> That's an interesting observation --- and I believe that it is
> correct when one is talking about an on-device cache --- would
> but it might not be the right thing for *every* cache for
> instance, a mobile gateway might find that
> "concentrating all negotation logic" as you put it is the right
> thing since it might asume that all its accesses come from mobile
> devices. On the other-hand, a caching firewall that serves both
> mobile and desktop clients should certainly not preserve the
> results of content negotiation since it would end up serving the
> wrong representation in the following scenario:
> 
> 0)    User-1 accesses http://example.com/info from a mobile
>       device
> 1)    caching firewall negotiates with example.com
> 2)    Serves user-1 http://example.com/info/mobile
> 3)    Later, user-2 accesses http://example.com/info through the
>       same firewall with a desktop device
> 
> Caching the results of the content negotiation performed for
>       user-1 would be incorrect.

That's what the HTTP Vary header is for, right (see 
<http://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.14.44>)?

 > ...

Best regards, Julian