Subject: draft-nottingham-http-link-header-01.txt - problem with default relationship base URI

From: Jonathan Rees <[email-masked]>
Date: Fri, 30 May 2008 11:15:52 -0400

Re http://tools.ietf.org/id/draft-nottingham-http-link-header-01.txt :

Relationship values are URIs that identify the type of link.  If the
    relationship is a relative URI, its base URI MUST be considered  
to be
    "http://www.iana.org/assignments/link-relations.html#", and the  
value
    MUST be present in the link relation registry.

My understanding of the way that a relative URI gets combined with a  
base URI (RFC 2396 section 5.2) is that if you combine the above base  
URI with "next" you get

http://www.iana.org/assignments/next

not

http://www.iana.org/assignments/link-relations.html#next

and I think you intend the latter, not the former.

Also, you might consider the possibility that the relations are  
backed by RDF/XML instead of or in addition to HTML. This is a detail  
but it could make a difference to RDF-aware applications. I don't  
know enough about IANA's taste to know whether this is feasible.

Regards,
Jonathan Rees
Science Commons and W3C TAG

---

From: Julian Reschke <[email-masked]>
Date: Fri, 30 May 2008 17:44:45 +0200

Jonathan Rees wrote:
>    relationship is a relative URI, its base URI MUST be considered to be
>    "http://www.iana.org/assignments/link-relations.html#", and the value

This is a known problem; IANA is serving the link relations page at 
<http://www.iana.org/assignments/link-relations.html>, but RFC4287 says 
that the base URI is <http://www.iana.org/assignments/relation/>. See 
<http://lists.w3.org/Archives/Public/ietf-http-wg/2008JanMar/0543.html>.

 > ...

BR, Julian

---

From: Julian Reschke <[email-masked]>
Date: Fri, 30 May 2008 17:57:21 +0200

Jonathan Rees wrote:
> ...
> Also, you might consider the possibility that the relations are backed 
> by RDF/XML instead of or in addition to HTML. This is a detail but it 
> could make a difference to RDF-aware applications. I don't know enough 
> about IANA's taste to know whether this is feasible.
> ...

 From <http://www.iana.org/about/projects/>:

"Conversion of Protocol Registries to XML

IANA intends to convert the internal formatting of all protocol 
registries it maintains to XML. This will allow easy exporting of these 
registries to the legacy text format, but also to other new formats that 
can be more easily machine read. Other possible features include 
syndication, RSS feeds of updates and so forth. The project is currently 
in a pilot, and consultations will be held with the IETF community 
before full implementation. IANA is also using an intermediary XML 
format internally for some of its other registries (such as the root 
zone database)."

So maybe there's hope...

BR, Julian

---

From: Jonathan Rees <[email-masked]>
Date: Fri, 30 May 2008 12:07:52 -0400

OK, good.

Regardless of where the documentation lives it looks like you should  
either use a base URI that ends in / or specify concatenation instead  
of relative URI resolution (which would be inelegant).

My vote would be for /, with a non-200 response to respect the idea  
that relations (in the sense of logical entities) don't have  
representations (in the sense of RFC 2616). The response could be,  
say, a 303, redirecting to a file containing documentation (maybe  
wrapped in RDF) for that relation.

Best
Jonathan

On May 30, 2008, at 11:44 AM, Julian Reschke wrote:

>> My understanding of the way that a relative URI gets combined with  
>> a base URI (RFC 2396 section 5.2) is that if you combine the above  
>> base URI with "next" you get
> <http://www.iana.org/assignments/link-relations.html>, but RFC4287  
> says that the base URI is <http://www.iana.org/assignments/relation/ 
> >. See <http://lists.w3.org/Archives/Public/ietf-http-wg/2008JanMar/ 
> 0543.html>.
>
> > ...
>
> BR, Julian