Re: MGET and machine processing

On Fri, Nov 21, 2003 at 06:20:12PM +0200, Patrick Stickler wrote:
> On Friday, Nov 21, 2003, at 17:14 Europe/Helsinki, ext Mark Baker wrote:
> > GET the-uri HTTP/1.1
> > Accept: application/rdf+xml
> >
> Sigh... I've addressed this use case so many times I've lost count.

I could say the same thing. 8-)

> If the resource denoted by the-uri *is* an RDF/XML instance, then
> the above request is *ambiguous*.

You can lookup what every byte in that message means in RFC 2616, RFC
2396, and the IANA media type registry, so there's no ambiguity at all.
Even if the the resource were a bag-o-bits or a timbl:Document (which
most aren't), the request makes sense.

For example, "" identifies the
RDF Forms namespace.  The namespace isn't an RDF/XML document, but an
RDF/XML can be returned by dereferencing the URI (i.e. can represent
the namespace).

> At first glance, it seems like GET, PUT, etc. should work fine,
> with a few headers tossed in, but in actual practice, it's a
> rat's nest.

Not in my experience.  I'm using HTML/RDF conneg in my current project,
and we've not had any problems.

> A SW agent should *not* have to examine the content returned
> to determine if it is what it asked for. Either the server
> understood what it meant (and the protocol is sufficiently
> precise to achieve that) and returned what the agent asked
> for, or it returns an error.

Sure, it's not ideal, and if HTTP had mandatory extensions we wouldn't
have this problem.  But it's by no means a big deal in this specific
case since you can just check if the media type that's returned is the
media type you asked for.  Suck it up! 8-)

> Anyway, have a nice weekend ;-)


Mark Baker.   Ottawa, Ontario, CANADA.

Received on Friday, 21 November 2003 14:01:33 UTC