Re: How to identify existing resource in a POST(a) request

Markus,

Your observation of the "demands of hypermedia" is exactly the point.  

1) Why would / should Facebook provide a link to a specific service?  
2) Without such a link, where should the "hypermedia following" client go?
3) Even if they (Facebook) desired to provide such a link, would this be possible? (presumably they would need some understanding of the resource state within the example.com domain)

I think what is becoming more clear (through this discussion) is that hypermedia links have to be provided by an authoritative source (in this case example.com).  How non-authoritative resources can interact in the media-type across "agency boundaries" is more complex, and needs more research (certainly be me, perhaps it's obvious to others).

Back to the 'Referer' question, I was investigating this partly to see if a standard HTTP header could be used instead of hyperlinks in some circumstances.  Digging back through the archives, I've found some commentary from Phill Hallam-Baker (proposer of the 'Referer' header) here, where he articulates the header's "intended purpose of making links bidirectional".  This intended purpose seems somewhat aligned, but I'm guessing that years of usage for tracking purposes has devalued the semantic a little (I'll think I'll get in touch with Phill directly on this).

So, I think that I am concluding that usage of the 'Referer' header for my purpose is incorrect, but it's on the basis of "common-usage" rather than conflict with the standard [RFC2616].

Thanks

Paul


On 27 Oct 2012, at 16:14, Markus Lanthaler wrote:

> So you are saying that every representation of a person has to contain a
> link to your "friend service"? So, to take your example,
> graph.facebook.com/2 must somewhere contain a link to example.com/friends?
> Otherwise, how did that URI "initiate the request"?
> 
> I think HTTP (bis) is quite clear on this:
> 
> The "Referer" [sic] header field allows the client to specify the URI
> of the resource from which the target URI was obtained (the
> "referrer", although the header field is misspelled.).
> 
> So I would say it's a bad design decision to use the referer header for the
> scenario you are outlining.