[urn] Fragments Re: I-D Action: draft-ietf-urnbis-rfc2141bis-urn-02.txt

[Leslie Daigle <[e-mail]>]

Hi,

I am having troubles reconciling this use of fragments with RFC3986, the 
URI syntax document.

My understanding of RFC3986 suggests that fragments are strictly and 
uniquely tied to media, and thus would be applied to the results of a 
URN resolution, irrespective of namespace.

So, if you have <urn>#<fragment>, you resolve <urn> and apply <fragment> 
in whatever way makes sense for the media type of what you got back.

The issue with doing that with URNs is:  they are designed to be 
flexible enough to support multiple types of response -- the URN does 
not designate a type.

For example, you might get a PDF back instead of HTML, and then your 
HTML #<fragment> will be pointless.

Even if you say (as the document currently does) that fragments are 
allowed only on a per-namespace basis, I am concerned that the resulting 
URN namespaces would have to be severely limited in terms of URN 
functionality:  you are essentially saying that those namespaces must be 
architected such that they only ever return single media type responses, 
or responses for which the fragments will make sense across all 
supported types.  That is very constraining on the namespace, and the 
use of URNs, IMO.

For myself, this doesn't make the case that the URN syntax can be 
updated to allow the use of fragment identifiers.

And, if the consensus winds up being that this does make the case to 
allow that, I would further argue that the text describing the 
per-namespace use considerations would need

1/  a very thorough review by URI experts to make sure it actually would 
hold water,

2/ to be clear about the constraints it puts on the overall URN 
namespace in question

3/ to be in a separate document all on its own, because it is severely 
distracting from a document that is meant to be the description of the 
syntax of URNs in general.

Leslie.



On 3/11/12 9:05 PM, [e-mail] wrote:
>
> A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Uniform Resource Names, Revised Working Group of the IETF.
>
> 	Title           : Uniform Resource Name (URN) Syntax
> 	Author(s)       : Alfred Hoenes
> 	Filename        : draft-ietf-urnbis-rfc2141bis-urn-02.txt
> 	Pages           : 32
> 	Date            : 2012-03-11
>
>     Uniform Resource Names (URNs) are intended to serve as persistent,
>     location-independent, resource identifiers.  This document serves as
>     the foundation of the 'urn' URI Scheme according to RFC 3986 and sets
>     forward the canonical syntax for URNs, which subdivides URNs into
>     "namespaces".  A discussion of both existing legacy and new
>     namespaces and requirements for URN presentation and transmission are
>     presented.  Finally, there is a discussion of URN equivalence and how
>     to determine it.  This document supersedes RFC 2141.
>
>     The requirements and procedures for URN Namespace registration
>     documents are set forth in BCP 66, for which RFC 3406bis is the
>     companion revised specification document replacing RFC 3406.
>
>
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-urnbis-rfc2141bis-urn-02.txt
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
> This Internet-Draft can be retrieved at:
> ftp://ftp.ietf.org/internet-drafts/draft-ietf-urnbis-rfc2141bis-urn-02.txt
>
> _______________________________________________
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