Subject: Atom namespace name

From: Tim Bray <[email-masked]>
Date: Wed, 10 Nov 2004 15:16:37 -0800

I've been talking with Scott Hollenbeck, our IETF area director, about 
IETF standard practice for namespace names, and he said:

<scott>
The closest thing we have to a guideline is described in RFC 3688.  I'd
recommend following the URN structure described in that document, but 
that
leaves some freedom for the string used to identify the namespace.
Something like "atom-1.0" could work, but I'm open to suggestions.

You can see the list of namespaces that have already been registered 
here:

http://www.iana.org/assignments/xml-registry/ns.html
</scott>

This would give us a namespace name something like 
"urn:ietf:params:xml:ns:atom" which is OK I guess.  I said that I liked 
HTTP URIs for namespace names because they leave open the door for 
putting some helpful info there and for things like RDDL.  Furthermore, 
in RFC3470, which Scott co-wrote, section 4.9 agrees with me.  So do 
sections 3.5  and 4.5.4 of the W3C's "Architecture of the World Wide 
Web".

Scott acknowledged this, but told me that if we go with the RFC3688 
flow, there will be no fuss, no muss, and we'll get our namespace name 
smoothly and quickly.  If we wanted to stand on principle for an HTTP 
name, we'd have to explain why to a whole bunch of people, and then 
there's the problem that the IETF doesn't maintain web space for this 
kind of thing, so maybe it should be in www.iana.org; anyhow, lots of 
extra work.

So... what's the sentiment of the WG?  -Tim

---

From: Dan Brickley <[email-masked]>
Date: Wed, 10 Nov 2004 18:47:10 -0500

* Tim Bray <[email-masked]> [2004-11-10 15:16-0800]
> So... what's the sentiment of the WG? 

In the absence of a widely deployed mechanism for getting from 
urn:* names to information about the things those URIs name, I'd much 
prefer use of http://* names. But my preferences there tend to be from
the RDF world, where I've a better idea what to do with
runtime-discovered namespace info. Perhaps not such a big deal for
XML-syntax oriented formats?

Dan

---

From: Bill de hÓra <[email-masked]>
Date: Wed, 10 Nov 2004 23:51:16 +0000

Tim Bray wrote:

> putting some helpful info there and for things like RDDL.  

So do I. But I could live with something like @rddl as well.

> So... what's the sentiment of the WG?  -Tim

Use the IETF way. Add an attribute on the root that contains a PURL 
for the docco.

Having people waffle on one more time about what's behind a 
namespace will not be conducive to getting things done.

cheers
Bill

---

From: Asbjørn Ulsberg <[email-masked]>
Date: Thu, 11 Nov 2004 01:12:16 +0100

> So... what's the sentiment of the WG?  -Tim

Although it might be a lot of fuzz (I don't understand why, but  
nonetheless..), I think we shuld strive to have an HTTP-based namespace  
URI for just the same reasons you enumerated.

Having the namespace URI point to an informational, human-readable HTML  
page is imho extremely important for Atom if we want it to be «newbie» and  
«View Source Clan» friendly. If we want it to be by techies for techies,  
any URI scheme will do the job.

What domain and space the HTTP URI points to is not very important, imho.  
purl.org has been used in examples and such, but anything would do it for  
me. Speaking of which: why can't IETF host this informational page, such  
as 'http://www.w3.org/1999/xhtml'?

-- 
Asbjørn Ulsberg         -=|=-        [email-masked]
«He's a loathsome offensive brute, yet I can't look away»

---

From: "Scott Hollenbeck" <[email-masked]>
Date: Wed, 10 Nov 2004 19:57:51 -0500

> -----Original Message-----
> From: Asbjørn Ulsberg [mailto:[email-masked]] 
> Sent: Wednesday, November 10, 2004 7:12 PM
> To: Tim Bray
> Cc: Atom-Syntax
> Subject: Re: Atom namespace name

[snip]

> any URI scheme will do the job.

The reason that this sort of reference has been a problem for the IETF is
that it's not a stable part of the standard.  The content can change over
time, with no community control.  Plus, the primary purpose of the URI in
this context is to uniquely identify a namespace -- and no more per recent
IETF practice.

I know that some view the ability to dereference a URL as one of the
strengths of the http URL approach.  I can guarantee, though, that it will
raise issues that we really don't need to get involved with when it comes
time for broad review of the specifications.  As I told Tim in our off-list
conversation, I'm not going to argue that the working group can't use http
URLs to identify namespaces.  You're just going to have to come up with a
VERY compelling reason for their use -- and the argument that they can be
used to provide a pointer to additional information is probably NOT the one
you want to use for just the reasons I provided above.

-Scott-

---

From: Paul Hoffman / IMC <[email-masked]>
Date: Wed, 10 Nov 2004 20:36:05 -0500

At 3:16 PM -0800 11/10/04, Tim Bray wrote:
>I've been talking with Scott Hollenbeck, our IETF area director, 
>about IETF standard practice for namespace names, and he said:
>
><scott>
>recommend following the URN structure described in that document, but that
>You can see the list of namespaces that have already been registered here:
>
>"urn:ietf:params:xml:ns:atom" which is OK I guess.  I said that I 
>liked HTTP URIs for namespace names because they leave open the door 
>for putting some helpful info there and for things like RDDL. 
>Furthermore, in RFC3470, which Scott co-wrote, section 4.9 agrees 
>with me.  So do sections 3.5  and 4.5.4 of the W3C's "Architecture 
>of the World Wide Web".
>
>flow, there will be no fuss, no muss, and we'll get our namespace 
>name smoothly and quickly.  If we wanted to stand on principle for 
>an HTTP name, we'd have to explain why to a whole bunch of people, 
>and then there's the problem that the IETF doesn't maintain web 
>space for this kind of thing, so maybe it should be in www.iana.org; 
>anyhow, lots of extra work.
>

Wearing my "IETF weenie co-chair" hat, I think we're fine asking for 
a URL instead of a URN. Both RFCs are also BCPs, and (distressingly) 
the latter RFC doesn't even mention the former one. Given two 
equal-level BCPs, we are under no pressure to accept the more recent 
one. I see no technical reason for us to have a namespace listed in 
the IANA registry, but am open to hear differently.

--Paul Hoffman, Director
--Internet Mail Consortium

---

From: Paul Hoffman / IMC <[email-masked]>
Date: Wed, 10 Nov 2004 20:42:06 -0500

[[ Whoops; I saw Scott's message after I sent mine ]]

At 7:57 PM -0500 11/10/04, Scott Hollenbeck wrote:
>time, with no community control.

Some people here consider that a feature, not a problem. :-)

>   Plus, the primary purpose of the URI in

Not sure how to parse that.

>you want to use for just the reasons I provided above.

Well, so far we haven't found other "very compelling" reasons.

--Paul Hoffman, Director

---

From: Martin Duerst <[email-masked]>
Date: Thu, 11 Nov 2004 10:01:22 +0900

At 09:12 04/11/11, Asbj$B�S(Bn Ulsberg wrote:
 >page is imho extremely important for Atom if we want it to be 'newbie' and
 >'View Source Clan' friendly. If we want it to be by techies for techies,

I agree.

 >me.

Yes. Something at IANA would do, too. Please note that we are already
asking IANA to permanently commit to a specific (base) URI for the
linking registry (PaceFieldingLinks).

Regards,    Martin.

---

From: Henry Story <[email-masked]>
Date: Thu, 11 Nov 2004 11:17:56 +0100

+1 for me for using a dereference-able URL.

Henry

---

From: Danny Ayers <[email-masked]>
Date: Thu, 11 Nov 2004 11:56:23 +0100

If we can have a http: scheme URI for the base of link rel, then why
not for the namespace?

Personally I would prefer a http: URI for the reasons Dan mentioned.
The use of these is widespread - every single namespace URI I have
seen in the context of syndication follows this pattern. Is current
practice compelling at all?

I fail to see why the IETF might object to a http: scheme URI given
their current use elsewhere, and the best current practice reflected
in the WebArch doc.

The benefit would be in human-discoverability of docs and machine
discoverability of schemas by dereferencing the URI with HTTP.

I note in passing that RFC 2396bis says:
[[
Future specifications and related documentation should use the general
term "URI", rather than the more restrictive terms URL and URN.
]]

Cheers,
Danny.

-- 

http://dannyayers.com

---

From: Dan Brickley <[email-masked]>
Date: Thu, 11 Nov 2004 06:34:58 -0500

* Danny Ayers <[email-masked]> [2004-11-11 11:56+0100]
> practice compelling at all?

On the extensibility front, there has been occasional mention here of 
possibility for transforming (by XSLT, or even XQuery) from Atom's
format into RDF/XML. W3C has a Note on one technique for doing so,
called GRDDL, which makes use of metadata about namespaces to 
figure out which XSLT-defined mappings are appropriate to get RDF/XML 
from some instance data. 

http://www.w3.org/TR/2004/NOTE-grddl-20040413/
http://www.w3.org/2003/g/data-view

esp. http://www.w3.org/TR/2004/NOTE-grddl-20040413/#ns-bind

I believe there's an implementation that consults namespace docs for 
this info 'while you wait', though to be fair I couldn't find it 
just now.

So the motivating scenario is that the AtomPub WG could make an
atom2rdf.xsl available and cite it from the Atom format's namespace
document in a machine-friendly way. This only becomes compelling if 
RDF toolkits start to acquire the ability to get their RDF via XSLT 
transforms, rather than just parsing RDF/XML notation. I think this 
is starting to happen, eg.
http://people.w3.org/~dom/archives/2004/11/grddl-support-in-rap/

Most of the attention around GRDDL to date has been w.r.t. the 
XHTML-oriented version, but it seems to have wider potential.

Dan