Jan,
>> Link headers provide a useful alternative to that of media types for certain cases of hypermedia support.
>
> No, I entirely do not think so because the focus on document oriented messaging is lost and I consider that essential.
>
> I'd only use link headers to provide hypermedia that is not very domain specific but rather general, for example
>
> - service documents
> - nex,previous,up,down
> - versions
I think you'd agree this isn't particularly useful for a purchase ordering system, right? We go back to the discussion about active vs. passive clients.
> Occasionally this could be loosened but I'd not recommend to stuff the domain semantics in a bunch of headers.
As Paul pointed out, we opted for headers for simplicity. I would very much like to see a proposal with hyperlinks in entities; I could even agree it is more natural and a better way to do it. It wouldn't be a lot harder to use Atom links as in RESTfulie; however, I think Atom links introduce a different set of problems and are not really the solution either.
>
> (Detailed response later)
OK. I'm interested in your exploration of media types to solve this.
-- Santiago