Lisa's Apps Area activity for Dec 2007

Application Area Architecture Workshop ("AAAW") host and attendance

URI for XML schema and namespace

What is the currently recommended form for a URI for an XML schema and an XML
namespace?

The question has come up on ForCES where I, citing RFC3688 say it should be urn:
whereas the others cite RFC3470 to say that http: is recommended.

Other opinions welcome.

Tom Petch

RE: URI for XML schema and namespace

> -----Original Message-----
> From: tom.petch [mailto:cfinss <at> dial.pipex.com] 
> Sent: Friday, January 04, 2008 8:19 AM
> To: Apps Discuss
> Subject: URI for XML schema and namespace
> 
> What is the currently recommended form for a URI for an XML 
> schema and an XML namespace?
> 
> The question has come up on ForCES where I, citing RFC3688 
> say it should be urn:
> whereas the others cite RFC3470 to say that http: is recommended.
> 
> Other opinions welcome.

Those folks looking at 3470 might have missed the third paragraph in section
4.9:

"In the case of namespaces in IETF standards-track documents, it would
be useful if there were some permanent part of the IETF's own web
space that could be used for this purpose.  In lieu of such, other
permanent URIs can be used, e.g., URNs in the IETF URN namespace"

URNs in the IETF namespace seems to be the more common practice in the IETF:

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

http://www.iana.org/assignments/xml-registry/schema.html

-Scott-

Re: URI for XML schema and namespace

Scott Hollenbeck wrote:
>> -----Original Message-----
>> From: tom.petch [mailto:cfinss <at> dial.pipex.com] 
>> Sent: Friday, January 04, 2008 8:19 AM
>> To: Apps Discuss
>> Subject: URI for XML schema and namespace
>>
>> What is the currently recommended form for a URI for an XML 
>> schema and an XML namespace?
>>
>> The question has come up on ForCES where I, citing RFC3688 
>> say it should be urn:
>> whereas the others cite RFC3470 to say that http: is recommended.
>>
>> Other opinions welcome.
> 
> Those folks looking at 3470 might have missed the third paragraph in section
> 4.9:
> 
> "In the case of namespaces in IETF standards-track documents, it would
> be useful if there were some permanent part of the IETF's own web
> space that could be used for this purpose.  In lieu of such, other
> permanent URIs can be used, e.g., URNs in the IETF URN namespace"
> ...

Unfortunately, the IETF so far hasn't followed the BCP's advice to 
actually make http-based namespace URIs available. Thus, if it's 
considered A Good Thing to provide a description of the namespace *at* 
the namespace URI - and when would it not? - I'd suggest to still use an 
http based namespace URL.

There are some IETF specs that for that very reason use URI assigned by 
the W3C (Atom, Atompub), and lots of other IETF specs use URIs on purl.org.

BR, Julian

Re: URI for XML schema and namespace

On Jan 4, 2008 7:42 AM, Scott Hollenbeck <sah-ietf <at> tengwar.com> wrote:

> > What is the currently recommended form for a URI for an XML
> > schema and an XML namespace?
> >
> > The question has come up on ForCES where I, citing RFC3688
> > say it should be urn:
> > whereas the others cite RFC3470 to say that http: is recommended.
> >
> > Other opinions welcome.

Well, the Architecture of the World Wide Web
(http://www.w3.org/TR/webarch) argues strongly that http: URIs are
generally useful on the grounds that they can in principle (don't have
to be, but can) be used to retrieve some human-readable explanatory
material about whatever it is the URI names.   Also the URI itself
tends to be a bit more human-readable, which seems worthwhile to me.

The downside, as Scott points out, is that if you want to do that, you
have to find a domain to put after the http:// part, and the IETF just
doesn't do that.  In the case of RFC4287 and 5023, we borrowed one
from the W3C.

 -Tim

RE: URI for XML schema and namespace

> -----Original Message-----
> From: Julian Reschke [mailto:julian.reschke <at> gmx.de] 
> Sent: Friday, January 04, 2008 10:54 AM
> To: Scott Hollenbeck
> Cc: 'tom.petch'; 'Apps Discuss'
> Subject: Re: URI for XML schema and namespace
> 
> Scott Hollenbeck wrote:
> >> -----Original Message-----
> >> From: tom.petch [mailto:cfinss <at> dial.pipex.com]
> >> Sent: Friday, January 04, 2008 8:19 AM
> >> To: Apps Discuss
> >> Subject: URI for XML schema and namespace
> >>
> >> What is the currently recommended form for a URI for an XML schema 
> >> and an XML namespace?
> >>
> >> The question has come up on ForCES where I, citing RFC3688 say it 
> >> should be urn:
> >> whereas the others cite RFC3470 to say that http: is recommended.
> >>
> >> Other opinions welcome.
> > 
> > Those folks looking at 3470 might have missed the third 
> paragraph in 
> > section
> > 4.9:
> > 
> > "In the case of namespaces in IETF standards-track 
> documents, it would 
> > be useful if there were some permanent part of the IETF's own web 
> > space that could be used for this purpose.  In lieu of such, other 
> > permanent URIs can be used, e.g., URNs in the IETF URN namespace"
> > ...
> 
> Unfortunately, the IETF so far hasn't followed the BCP's 
> advice to actually make http-based namespace URIs available.

As one of the authors of 3470 I can say very clearly that 3470 doesn't
provide advice on this point.  It states fact:

"Typically (and recommended practice in W3C) is to assign namespace names
using persistent http URIs."

Notice that there's no "may", "should", "must", etc.

> Thus, if it's considered A Good Thing to provide a 
> description of the namespace *at* the namespace URI - and 
> when would it not? - I'd suggest to still use an http based 
> namespace URL.
> 
> There are some IETF specs that for that very reason use URI 
> assigned by the W3C (Atom, Atompub), and lots of other IETF 
> specs use URIs on purl.org.

That's certainly a valid option.  I'm not saying that one is better than the
other. What I am saying is that people shouldn't think that 3470 recommends
one over the other.

-Scott-

Re: URI for XML schema and namespace

Scott Hollenbeck wrote:
>> Unfortunately, the IETF so far hasn't followed the BCP's 
>> advice to actually make http-based namespace URIs available.
> 
> As one of the authors of 3470 I can say very clearly that 3470 doesn't
> provide advice on this point.  It states fact:
> 
> "Typically (and recommended practice in W3C) is to assign namespace names
> using persistent http URIs."
> 
> Notice that there's no "may", "should", "must", etc.

It also says:

    In the case of namespaces in IETF standards-track documents, it would
    be useful if there were some permanent part of the IETF's own web
    space that could be used for this purpose. (...)

Isn't that advice?

> ...

BR, Julian

RE: URI for XML schema and namespace

Has anybody actually asked Ray to get such a  permanent part of IETF's
own web space allocated and setup? Would entries on the web site
require IANA assignment, e.g. as a registry?

I'm asking because I am new to the discussion, and simply don't know
the answer.

dbh

> -----Original Message-----
> From: Scott Hollenbeck [mailto:sah-ietf <at> tengwar.com] 
> Sent: Friday, January 04, 2008 11:04 AM
> To: 'Julian Reschke'
> Cc: 'Apps Discuss'
> Subject: RE: URI for XML schema and namespace
> 
> > -----Original Message-----
> > From: Julian Reschke [mailto:julian.reschke <at> gmx.de] 
> > Sent: Friday, January 04, 2008 10:54 AM
> > To: Scott Hollenbeck
> > Cc: 'tom.petch'; 'Apps Discuss'
> > Subject: Re: URI for XML schema and namespace
> > 
> > Scott Hollenbeck wrote:
> > >> -----Original Message-----
> > >> From: tom.petch [mailto:cfinss <at> dial.pipex.com]
> > >> Sent: Friday, January 04, 2008 8:19 AM
> > >> To: Apps Discuss
> > >> Subject: URI for XML schema and namespace
> > >>
> > >> What is the currently recommended form for a URI for an 
> XML schema 
> > >> and an XML namespace?
> > >>
> > >> The question has come up on ForCES where I, citing 
> RFC3688 say it 
> > >> should be urn:
> > >> whereas the others cite RFC3470 to say that http: is
recommended.
> > >>
> > >> Other opinions welcome.
> > > 
> > > Those folks looking at 3470 might have missed the third 
> > paragraph in 
> > > section
> > > 4.9:
> > > 
> > > "In the case of namespaces in IETF standards-track 
> > documents, it would 
> > > be useful if there were some permanent part of the IETF's own
web 
> > > space that could be used for this purpose.  In lieu of 
> such, other 
> > > permanent URIs can be used, e.g., URNs in the IETF URN
namespace"
> > > ...
> > 
> > Unfortunately, the IETF so far hasn't followed the BCP's 
> > advice to actually make http-based namespace URIs available.
> 
> As one of the authors of 3470 I can say very clearly that 3470
doesn't
> provide advice on this point.  It states fact:
> 
> "Typically (and recommended practice in W3C) is to assign 
> namespace names
> using persistent http URIs."
> 
> Notice that there's no "may", "should", "must", etc.
> 
> > Thus, if it's considered A Good Thing to provide a 
> > description of the namespace *at* the namespace URI - and 
> > when would it not? - I'd suggest to still use an http based 
> > namespace URL.
> > 
> > There are some IETF specs that for that very reason use URI 
> > assigned by the W3C (Atom, Atompub), and lots of other IETF 
> > specs use URIs on purl.org.
> 
> That's certainly a valid option.  I'm not saying that one is 
> better than the
> other. What I am saying is that people shouldn't think that 
> 3470 recommends
> one over the other.
> 
> -Scott-
> 
> 
> 
> 

Re: URI for XML schema and namespace

Tim Bray wrote:
> On Jan 4, 2008 7:42 AM, Scott Hollenbeck <sah-ietf <at> tengwar.com> wrote:
> 
>>> What is the currently recommended form for a URI for an XML
>>> schema and an XML namespace?
>>>
>>> The question has come up on ForCES where I, citing RFC3688
>>> say it should be urn:
>>> whereas the others cite RFC3470 to say that http: is recommended.
>>>
>>> Other opinions welcome.
> 
> Well, the Architecture of the World Wide Web
> (http://www.w3.org/TR/webarch) argues strongly that http: URIs are
> generally useful on the grounds that they can in principle (don't have
> to be, but can) be used to retrieve some human-readable explanatory
> material about whatever it is the URI names.   Also the URI itself
> tends to be a bit more human-readable, which seems worthwhile to me.

If http URI, type into browser location bar.

If URN, type into browser search bar.

I don't see a great deal of difference. :)

> The downside, as Scott points out, is that if you want to do that, you
> have to find a domain to put after the http:// part, 

... and ensure that the domain is stable, and that the people running 
the domain will reliably host your namespace, and ...

> and the IETF just
> doesn't do that.  In the case of RFC4287 and 5023, we borrowed one
> from the W3C.

FWIW, we Jabberites used https URIs like http://jabber.org/protocol/* 
for a long time but recently switched to URNs like urn:xmpp:* because 
they're more stable (what happens if the person registering jabber.org 
loses control over the domain?) and will last forever.

The choice of http URI vs. URN seems like a toss-up to me.

Peter

--

-- 
Peter Saint-Andre
https://stpeter.im/