rfc:rfc3613
Network Working Group R. Morgan Request for Comments: 3613 Univ. of Washington Category: Informational K. Hazelton
Univ. of Wisconsin-Madison
October 2003
Definition of a Uniform Resource Name (URN) Namespace for the
Middleware Architecture Committee for Education (MACE)
Status of this Memo
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document describes a Uniform Resource Name (URN) namespace for the Internet2 Middleware Architecture Committee for Education (MACE). This namespace is for naming persistent resources defined by MACE, its working groups and other designated subordinates.
1. Introduction and Community Considerations
The Internet2 Middleware Architecture Committee for Education (MACE) produces many kinds of documents: specifications, working drafts, object classes, schemas, stylesheets, etc. It also defines directory attributes and controlled vocabularies for the values of some of those attributes.
MACE wishes to provide global, distributed, persistent, location- independent names for these resources. The Uniform Resource Name (URN) variant of URIs meets these requirements.
MACE working groups and other MACE-affiliated groups will benefit from the MACE URN namespace by having an easy, efficient way to assign globally unique, persistent identifiers to resources that they create. The nature of MACE work is that serves the needs of one or more communities of interest. A namespace managed so as to facilitate the creation, registration and resolution of unique, persistent identifiers will be of great value for MACE, its affiliates and the higher education community generally.
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This URN namespace specification is for a formal namespace.
2. Specification Template
Namespace ID:
"mace"
Registration Information:
Registration Version Number 1
Registration Date: 2003-08-01
Registrant of the namespace:
Middleware Architecture Committee for Education (MACE)
ATTN: Lisa Hogeboom
Internet2
3025 Boardwalk Suite 200
Ann Arbor, MI 48108
Phone: +1 734 913 4250
Contact: Keith Hazelton
Affiliation: Univ. of Wisconsin-Madison
1210 W. Dayton St.
Madison, WI 53706
Phone: +1 608 262 0771
hazelton@doit.wisc.edu
Syntactic structure:
The Namespace Specific Strings (NSS) of all URNs assigned by MACE
will conform to the syntax defined in section 2.2 of RFC 2141,
"URN Syntax" [1]. In addition, all MACE URN NSSs will consist of
a left-to-right series of tokens delimited by colons. The left-
to-right sequence of colon-delimited tokens corresponds to
descending nodes in a tree. To the right of the lowest naming
authority node there may be zero, one or more levels of
hierarchical naming nodes terminating in a rightmost leaf node.
See the section entitled "Identifier assignment" below for more on
the semantics of NSSs. This syntax convention is captured in the
following normative ABNF rules for MACE NSSs (see RFC 2234) [2]:
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MACE-NSS = 1*(subStChar) 0*(":" 1*(subStChar))
subStChar = trans / "%" HEXDIG HEXDIG
trans = ALPHA / DIGIT / other / reserved
other = "(" / ")" / "+" / "," / "-" / "." /
"=" / "@" / ";" / "$" /
"_" / "!" / "*" / "'"
reserved = "%" / "/" / "?" / "#"
The exclusion of the colon from the list of "other" characters
means that the colon can only occur as a delimiter between string
tokens. Note that this ABNF rule set guarantees that any valid
MACE NSS is also a valid RFC 2141 NSS.
Relevant ancillary documentation:
None.
Identifier uniqueness:
It is the responsibility of MACE directors to guarantee uniqueness
of the names of immediately subordinate naming authorities. Each
lower-level naming authority in turn inherits the responsibility
of guaranteeing uniqueness of names in their branch of the naming
tree.
Identifier persistence:
MACE directors bear ultimate responsibility for maintaining the
usability of MACE URNs over time. This responsibility may be
delegated to subordinate naming authorities per the discussion in
the section below on identifier assignment. That section provides
a mechanism for the delegation to be revoked in case a subordinate
naming authority ceases to function.
Identifier assignment:
MACE directors will create an initial series of immediately
subordinate naming authorities, and will define a process for
adding to that list of authorities. Each top-level working group
of MACE will be invited to designate a naming authority and to
suggest one or more candidate names for that authority. The
MACE-Shibboleth group, for example, might propose creating a
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naming authority under "urn:mace:shib," "urn:mace:shibboleth" or
some other name.
Institutions and communities affiliated with MACE may request,
through their designated MACE liaison, that they be granted MACE-
subordinate naming authority status. They may propose candidate
names for that authority. One way for such entities to guarantee
uniqueness of their proposed name is to base it on a DNS name.
That is, if Georgetown University wished to be designated a
subordinate naming authority under MACE, the institutional MACE
liaison could propose to MACE directors that they be delegated
control over names beginning with "urn:mace:georgetown.edu".
Institutions seeking affiliation with MACE should send email to
mace-submit@internet2.edu, nominating an institutional liaison and
providing contact information for that person.
On at least an annual basis, MACE directors will contact the
liaisons or directors of each immediately subordinate naming
authority. If there is no response, or if the respondent
indicates that they wish to relinquish naming authority, the
authority over that branch of the tree reverts to MACE. This
process will be enforced recursively by each naming authority on
its subordinates. This process guarantees that responsibility for
each branch of the tree will lapse for less than one year at worst
before being reclaimed by a superior authority.
Lexical equivalence of two MACE namespace specific strings (NSSs)
is defined below as an exact, case-sensitive string match. MACE
will assign names of immediately subordinate naming authorities in
a case-insensitive fashion, so that there will not be two MACE-
subordinate naming authorities whose names differ only in case.
Identifier resolution:
MACE directors will maintain an index of all MACE and MACE
workgroup assigned URNs at the web site
http://middleware.internet2.edu/urn-mace/urn-mace.html. That
index will map URNs to resource identifiers or resource
specifications (e.g., protocol parameters). MACE-affiliated
naming authorities will specify how to resolve the URNs they
assign if they are resolvable.
Lexical equivalence:
Lexical equivalence of two MACE namespace specific strings (NSSs)
is defined as an exact, case-sensitive string match.
Conformance with URN syntax:
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All MACE NSSs fully conform to RFC 2141 syntax rules for NSSs.
Validation mechanism:
As specified in the "Identifier resolution" section above, MACE
directors will maintain an index of all MACE and MACE workgroup
assigned URNs on its web site,
http://middleware.internet2.edu/urn-mace/urn-mace.html. Presence
in that index implies that a given URN is valid. MACE-affiliated
naming authorities will specify how to validate the URNs they
assign.
Scope:
Global.
3. Security Considerations
There are no additional security considerations beyond those normally associated with the use and resolution of URNs in general.
4. Namespace Considerations
Registration of an NID specific to MACE is reasonable given the following considerations:
1. MACE would like to assign URNs to some very fine-grained objects
(such as specific controlled vocabulary values of an attribute in
MACE-defined LDAP object classes). This does not seem to be the
primary intended use of the XMLORG namespace (RFC 3120) [3], let
alone the more tightly controlled OASIS namespace (RFC 3121) [4].
2. MACE seeks naming autonomy. We understand that the XMLORG
registrants left the door open to subordinate naming authorities,
"OASIS may assign portions of its XMLORG namespace for assignment
by other parties" (RFC 3120) [3], but there is no specified
process for such assignment. That would in any case mean having a
fixed XMLORG-assigned prefix on every single object to which we
assign a URN. MACE has a number of active work groups that may
well generate a growing number of subordinate naming authorities.
Moreover, MACE is not a member of OASIS, so becoming a subordinate
naming authority under the OASIS URN space is currently not an
option.
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3. MACE will want to assign URNs to non-XML objects as well. That is
another reason that XMLORG may not be an appropriate higher-level
naming authority for MACE.
Some MACE-developed schema and namespaces may be good candidates for inclusion in the XMLORG registry. The fact that such an object might already have a MACE-assigned URN shouldn't be a hindrance. Work is in progress to update RFC 2611 [5], which includes an explicit statement that two or more URNs may point to the same resource. A resource with a MACE-assigned namespace-specific-string would, of course, be given an XMLORG namespace-specific-string at the time it enters the XMLORG registry.
5. IANA Considerations
The IANA has formally registered URN namespace 13 to MACE, within the IANA registry of URN NIDs.
6. Normative References
[1] Moats, R., "URN Syntax", RFC 2141, May 1997.
[2] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[3] Best, K. and N. Walsh, "A URN Namespace for XML.org", RFC 3120,
June 2001.
[4] Best, K. and N. Walsh, "A URN Namespace for OASIS", RFC 3121,
June 2001.
[5] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, "URN
Namespace Definition Mechanisms", BCP 33, RFC 2611, June 1999.
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7. Authors' Addresses
RL "Bob" Morgan 4545 15th Ave. NE Seattle, WA 98105 U.S.A.
EMail: rlmorgan@washington.edu
Keith D. Hazelton University of Wisconsin-Madison 1210 W. Dayton St. Madison, WI 53706 U.S.A.
EMail: hazelton@doit.wisc.edu
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8. Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
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Acknowledgement
Funding for the RFC Editor function is currently provided by the Internet Society.
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