Re: Media types and rss (was Re: Using dc:language vs language)

Hello Alan,

On 6/13/07, Alan Dean <[email protected]> wrote:
>
> On 6/12/07, Charles Iliya Krempeaux <[email protected]> wrote:
>  >
>  > Hey Lucas,
>  >
>  > On 6/12/07, Lucas Gonze <[email protected]> wrote:
>  > >
>  > > On 6/11/07, Charles Iliya Krempeaux <[email protected]> wrote:
>  > > > Consider a video that is made of up 2 video clips.
>  > >
>  > > Another way of tackling this --
>  > >
>  > > Both A and B are media HTTP links encountered by an RSS user agent
>  > > with good support for HTTP caching. When the RSS user agent initially
>  > > encounters these links it fetches them. A has a cache expiration date
>  > > far in the future. B has an cache expiration date. When the user
>  > > agent is requested by the user to render them, it checks the
>  > > expiration and finds that A can be served from cache but B has to be
>  > > re-requested.
>  >
>  > I agree that HTTP provides some useful semantics through the HTTP
>  > "Cache-Control" header (as well as with the ETag and Last-Modifed
>  > mechanisms... with the conditional GETs)... however, it would be nice
>  > to get rid of that initial download, if possible, IMO.
>  >
>  > [snip]
>  >
>  > If we wanted to stick to HTTP... which would be a good thing IMO...
>  > then what I think we'd need is a (new) "conditional GET" where we can
>  > say something like...
>  >
>  > Return the contents of this "resource" only if I can cache it for
>  > "X" amount of time.
>  >
>  > Where "X" would be a very large number.
>
>  If I understand your use-case correctly, you don't need a new
>  conditional request header. The User Agent should send a HEAD request.
>  This will provide the Cache-Control and other response headers
>  discussed without the body - so will have a very small bandwidth
>  footprint.
>
>  http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.4

That's good to know.

Given that's the case, a new Conditional GET wouldn't be worth it.
Like you alluded to... just make the HEAD request... and if you get
the right headers to say you can cache it for a long time... then make
another GET request.


See ya

-- 
    Charles Iliya Krempeaux, B.Sc. <http://ChangeLog.ca/>


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