Network Working Group R. Morgan
Internet-Draft Univ. of Washington
Expires: November 11, 2002 K. Hazelton
Univ. of Wisconsin-Madison
May 13, 2002
A URN Namespace for MACE
draft-hazelton-mace-urn-namespace-00
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Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document describes a proposed URN (Uniform Resource Name)
namespace that would be managed by the Internet2 Middleware
Architecture Committee for Education (MACE) for naming persistent
resources defined by MACE, its working groups and other designated
subordinates.
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1. Introduction
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.
The proposed URN namespace specification is for a formal namespace.
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2. Specification Template
Namespace ID:
"mace" requested.
Registration Information:
Registration Version Number 1
Registration Date: 2002-xx-yy
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 following syntactic rule: All MACE URN
NSSs must consist of a left-to-right series of tokens delimited
by colons. If the tokens themselves include colons, those
colons must be escaped as the hexadecimal value for a colon in
ASCII, "%3A." The left-to-right sequence of colon-delimited
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tokens corresponds to descending nodes in a tree. One or more
of the initial nodes correspond to naming authorities. Below
the naming authority node(s) there may be zero, one or more
levels of hierarchical nodes. The rightmost string is a leaf
node under the naming authority.
See the section on Identifier Assignment below for an
explanation of the semantics behind this syntax.
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 stand up a naming authority
and to suggest one or more candidate names for that authority.
The MACE-Shibboleth group, for example, might propose creating
a 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
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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 MUST 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 MUST 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 lower case only. This forestalls the
registration of two MACE-subordinate naming authorities whose
names differ only in case.
Identifier resolution:
MACE directors MUST maintain an index of all MACE and MACE
workgroup assigned URNs on its web site, http://
middleware.internet2.edu/MACE. That index will map URNs to
resource identifiers, usually URLs. MACE-affiliated naming
authorities MUST 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:
No special considerations.
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/
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MACE. Presence in that index implies that a given URN is
valid. MACE-affiliated naming authorities MUST specify how to
validate the URNs they assign.
Scope:
Global.
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3. Security Considerations
There are no additional security considerations beyond those normally
associated with the use and resolution of URNs in general.
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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 (rfc3120), let alone the
more tightly controlled OASIS namespace (rfc3121).
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" (rfc3120), 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,
making for longer strings. We have 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 a current option.
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 in
progress to update RFC2611 includes an explicit statement that two or
more URNs may point to the same resource (see draft-ietf-urn-
rfc2611bis-04). 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.
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5. Community Considerations
MACE working groups and other MACE-affiliated groups would benefit
from the MACE URN proposal by having an easy, efficient way to assign
globally unique, persistent identifiers to resources that they
create. The nature of MACE work is that it is carried out to serve
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 would be of great value for MACE,
its affiliates and the higher education community generally.
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6. IANA Considerations
This document is intended as a formal request to IANA for the
registration of a "MACE" NID within the IANA registry of URN NIDs.
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References
[1] Moats, R., "URN Syntax", RFC 2141, May 1997.
[2] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, "URN
Namespace Definition Mechanisms", BCP 33, RFC 2611, June 1999.
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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