Hi Folks,
* Content Negotiating for Package Formats
RFC2533 seems massive overkill, and very different from HTTP content
negotiation.
Could you set out the requirements that cannot be fulfilled by accept
headers? My understanding is that the packaging format and the wrapped
media format should be separately negotiable, but that can be handled with
just a single new Accept- header that handles the wrapped data's format.
[As the packaging is the outermost layer, it goes into Accept]
If RFC2533 is the way you decide to go, then you should follow RFC2295
Section 6, which discusses a Accept-Features. Note in RFC 2616 (HTTP)
defined after 2533/2295, it doesn't mention Accept-Features. However,
2295 defines a different syntax than 2533, and 2533 doesn't appear to
officially update 2295. Transparent Content Negotiation from 2295 is very
poorly implemented, and 2533 doesn't appear to be implemented at all.
Basically, ... don't do it. Whatever the problem is, 2295 + 2533 is not
the solution.
Regarding this, perhaps the easiest thing to do is share my first stab
at an internet draft for the various HTTP headers that look relevant to
SWORD 2.0.
http://sword-app.svn.sourceforge.net/viewvc/sword-app/spec/trunk/PackagedContentDelivery.txt?revision=226&view=markup
Feel free to mock my first attempt at writing anything of this nature -
I've hacked it together from a variety of example sources, and hope that
it's the right sort of thing, but any hints as to how to make it better
would be great.
The main point, though, is that it describes briefly the
Accept-Media-Formats header with its constrained contents, which will
hopefully clarify what we're trying to achieve.
I originally discarded Accept-Features, because the definition of it
seemed to concern the features of the request, rather than any content
negotiation (in Section 8.2 of RFC2295):
"The Accept-Features request header can be used by a user agent to give
information about the presence or absence of certain features in the
feature set of the current request."
Must be I'm reading that wrong.
The more we discuss it the more I'm leaning towards a lazy approach of
having a separate Accept-Packaging header, and some clearly stated rules
as to the way in which servers should interpret the combination of
Accept and Accept-Packaging. This issue must arise in other types of
content negotiation, for example with Accept-Language where not all
content-types are available in all languages, so perhaps there are some
resources on that that we can learn from.
Cheers,
Richard
