Minutes of URI BOF - IETF 56 - 2003-03-20

Minutes of URI BOF - IETF 56 - 2003-03-20
Session chaired by Larry Masinter
Reported by Graham Klyne with edits by Larry Masinter.

(1) URI to standard
(2) IRI to proposed standard
(3) Discuss processes for URI registration
(4) Review other URI-related work needed


(1) URI to standard

We discussed draft-fielding-uri-rfc2396bis-01.txt and open issues in
http://www.apache.org/~fielding/uri/rev-2002/issues.html .

Status of the URI-comparision section 6.2: This is new text,
originally contributed by Tim Bray (W3C TAG). (An earlier version of
the document had a placeholder for this.)

Roy is waiting for people to submit examples!  Please do so!

Implementers tend to normalize dot segments in *any* URI (relative or
otherwise) -- these should be disallowed as path segments in full URI?

008-URIvsURIref:  (URI includes with fragments?)
-Michael Mealling: Distinguish between terminology used when people
 are lazy and terminology in specifications.  The distinction should
 be kept concrete in the spec.
-GK: finds TimBL distinction between identifer and reference to be
-Larry: Choices: leave old terms, change definition, define new
 terms. Changing is problematic.  At best introduce new terms (for BNF
 in document).
-Roy: Currently no 'URI' production in the document.
-MM: prefer some other term; any suggestions?  No.  Prefers no new

Straw poll of the room seemed to favor 'no new term'.

Roy noted that the current draft has a BNF production for

One cannot use the fragment to indicate relative to a base document,
other than to the current document.  Some want to allow XML parsers
for RDF to use base URI+fragment together.  The proposal would replace
discussion in current document with extended discussion of retrieval
when base is same as current document. There was support for this the

022-definitions: definitions for operations on URIs; e.g. resolution,
dereference, retrieval.  The proposal came from Stuart Williams on W3C
TAG list.  Current intent is to incorporate these definitions
introduction section. Larry noted that they needed some editing &
offered to help. Ted Hardie volunteered to edit the text on URI

024-identity: rework to avoid problematic issues of resource identity.
-Larry: People seem to interpret permission for a resource to 'be
 anything that has identity' to be a requirement.  Intent of rework is
 to avoid this issue.
-MM: Resources in RFC2396 only exist when bound to URI.

Discussion about RDF and its needs: "If RDF has problems with the
'meaning' of URIs, it's RDF's problem, not URI's problem." The room
hummed in agreement with this assertion.

034-identifier: ('identifier is not just a sequence of characters')
Larry suggested we reject this issue. Roy explained that it was
missing context and that the sentence before actually said what the
proposal wanted the document to say.

036-host-escaping;  allow %hh in host name?
We deferred this issue to the IRI discussion. 

038-qualified (syntax production)
This issue is about the attemps to provide syntactic distinction
between domain and IP address.  We discussed what RFC 1034/1123 allow
in domain names; there was some question about whether it
matters. Surprisingly, there are no other definition to reference for

We were out of time to review issues, but set a goal to have a
document ready for last-call before next IETF. The document and open
issues should be reviewed by everyone.

(2) IRI to proposed standard

Martin Duerst reviewed the status of draft-duerst-iri-03.txt using the
presentation at http://www.w3.org/2003/03/ietf-uri-bof-iri.html .

Currently discussion is being held on: www-international@w3.org (but
see below).  The plan is to resolve remaining issues, submit as
individual draft for proposed standard.  Martin noted the major edits
in the last two versions; these included, for example, bug fix from
RFC2396bis, and a new BIDI section.

Note that IRIs are already used (in some form) in several W3C specs
(e.g. XML for system identifiers).

Martin reviewed open issues:

Issue iadditional: Allow characters in iadditional production?  

(<, >, ", SPACE, {, }, |, \, ^, `) are not allowed in URIs; in the
current draft, they are allowed in IRIs.

-Roy: must distinguish what's used in the syntax, and what characters
 can be represented.  Criteria is to pick solution with best
-MM: people are lazy, but this is not a good reason to break
 interoperability.  %-escaping of these things is OK (general
 agreement).  Don't do this.
-Leslie Daigle: We should separate two questions (a) are spaces in
 identifiers good in principle?  (b) ... Note that backward
 compatibility less of an issue, if IRIs aren't URIs, because this is
 new item.
-Paul Hoffman: There may be security problems: IRIs are sufficiently
 like URIs that people will use old RI code as a basis for
 IRI-handling. Changing the allowed characters may introduce security
 problems. URI-using applications assume that certain characters are
 allowed as separators in data. Changes to reserved characters may
 lead to unexpected behavior, and possible exploits against the

There was some discussion of whether or not current specifications
mandate %-escaping for space characters in URIs.  The consequence of
this might be that requiring or not requiring %-escaping of spaces in
IRIs impacts the ease of migrating URI-using software to use IRIs.

-Martin: We might define IRIs to not include spaces, but allow some
 components to use "IRI with space" and to escape from space to %20
 when extracting IRIs from such components.
-Michel Suignard: Don't confuse IRI with URI: cannot use IRI in
 protocol that requires a URI. Space is a different problem than the
 other characters.  Code points other than 0x20 are also spaces; if
 0x20 is disallowed, have to think about disallowing other space
-Larry: reasons to allow these characters are not strong.  That some
 implementations may allow them, is not a reason to change protcol
 spec in ways that are problematic. The characters chosen to be
 disallowed, at the time, were chosen for good reasons. Now that there
 is so much software that ssumes those characters are disallowed, the
 reasons are stronger, not weaker.
-Michel: there are visually similar characters that should be treated
-Larry: No different from avoiding 'upper case greek Alpha'.
-TedH: The 'side-of-bus' issue is a rathole.  Pretend I'm being mean:
 require some otherwise forbidden character to appear in IRIs, as a
 flag to signal IRI context.  We need to figure how to take this
 string of characters and put it on the wire.

Issue alignment:
It was noted to align the description in sect 2.3 with W3C TAG
discussion of URI equivalence. This issue is considered solved; the
TAG came to a conclusion that is essentially the same as what is
already in the draft.

Issue IDNURI: How to allow internationalized domain names in URIs?
(also URI issue 036-host-escaping)

General approach (recommended): convert to UTF-8, then use %hh
escaping.  Alternatives for URIs with IDN: escape -> IDN, or go
straight to IDN Which form is used for resolution via URIs, as opposed
to direct resolution?  %-escaping of Unicode IDN, or converted IDN
-Roy: one way requires URI spec to allow %-encoding in URIs, and DNS
 resolvers to recognize %-encoding.  Alternative is to disallow
 alternative registry names in URI authority components.  Otherwise,
 IRI->URI conversion becomes scheme-dependent.
-MS:  take all things into consideration in URI->IRI mapping
-Larry: The 'host' part of a URI in HTTP doesn't just affect what the
 client uses to look up the domain name, it also specifies what goes
 in the Host: header. If this is changed to allow I18N host names,
 does it require a HTTP spec update? The HTTP spec would need updating
 to specify one way or another, because otherwise it is
 ambiguous. What about other protocols? Are host names from URIs also
 sent over the wire? Asked about mailto:, sip:, ... We may need new
 issue for IRI draft to review existing URI schemes to check that IRI
 form maps appropriately for the protocol that is to use it.
-TedH: does that mean update all URI schemes?  Will IRIs be usable in
 any scheme currently defined for URIs?
-Martin: yes, that was intent.

There are concerns about scheme-dependency.

Process for moving forward:
(a) Agreement we should make a new list focused only on IRIs
(b) There will likely be a longer timeframe than RFC2396bis
(c) Martin's proposed schedule looks aggressive.
(d) Martin will publish the issue list and keep it up to date.

(3) Discuss processes for URI registration

Patrik: How do ADs know when proposed URI scheme has had sufficient
review?  Have created a new mailing list: <uri-review@ietf.org> Will
be updated on apps area web page.

Most of procedure is the same (send URI proposal to area director),
but the area director will then conduct review on that mailing list
(so archives of review are easily accessible).

This does not include URN namespaces: they are reviewed on
urn-names@ietf.org.  The URI scheme registration document should be
updated to reflect this change.

Roy will edit URI process document.

Martin: note that uri@w3.org is an IETF list that happens to be hosted
by W3C, and doesn't reflect W3C policy.

Additional info: The W3C URI coordination group has now been

(4) Review other URI-related work needed
RFC1738 is mainly obsolete, but has the only definition of some URI
schemes, notably the 'file:' scheme. Other schemes which are defined
in 1738 from http://www.iana.org/assignments/uri-schemes include ftp:,
gopher:, news:, nntp:, wais:, telnet:, prospero:. Some of these can be
left behind, others redefined by other working groups (news:, nttp:),
and others updated independently.

Dan Kohn and Paul Hoffman volunteered to scope the work and take on
some or all of it.


Michael Mealling noted DDDS has ben published, and IANA name servers
have been set up to handle the zone uri.arpa. Larry asks Michael to
make it clear what this means can now be done.

There was a comment that RFC2396bis had a dependency on RFC2234, which
is currently 'proposed standard', which might interfere with it moving
to full standard. The plan is that RFC2234 will go to BCP which will
solve the problem.

We noted that work was proceeding well without any formal working
groups established, and that we would continue as planned.

Received on Wednesday, 26 March 2003 17:14:36 UTC