Internet Engineering Task Force (IETF) V. Giralt
Request for Comments: 6338 Univ. Malaga
Category: Informational R. McDuff
ISSN: 2070-1721 Univ. Queensland
August 2011
Definition of a Uniform Resource Name (URN) Namespace
for the Schema for Academia (SCHAC)
Abstract
This document describes a Uniform Resource Name (URN) namespace for
the Schema for Academia (SCHAC).
The namespace described in this document is for naming persistent
resources defined by the SCHAC participants internationally, their
working groups, and other designated subordinates. The main use of
this namespace will be for the creation of controlled vocabulary
values for attributes in the SCHAC schema. These values will be
associated with particular instances of persons or objects belonging
to any of the SCHAC object classes.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6338.
Giralt & McDuff Informational [Page 1]RFC 6338 SCHAC URN Namespace August 2011
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License.
1. Introduction
The Schema for Academia (SCHAC) international activity was born
inside the Task Force on European Middleware Coordination and
Collaboration (TF-EMC2) of the Trans-European Research and Education
Networking Association (TERENA) [6]. The initial aim of SCHAC was to
harmonize the disjoint person schemas of the participating countries
in order to have a common way for expressing data about persons,
exchanged between educational organizations. SCHAC, as are other
person schemas, is designed to ease the sharing of information about
a given individual between parties, mostly, but not limited to,
educational and research institutions. The main aims of this sharing
are to provide resources to individuals and to allow said individuals
to move, virtually and physically, between such institutions. Thus,
the SCHAC schema was defined with input from all participants'
national person schemas [7].
SCHAC does not supplant other person schemas such as
organizationalPerson [8], inetOrgPerson [9], or eduPerson [10]; it
extends those where needed for the purposes of Higher Education
outside the United States. This characteristic has made SCHAC,
originally a European effort, useful for groups outside Europe.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [1].
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RFC 6338 SCHAC URN Namespace August 2011
3. Specification Template
Namespace ID:
schac
Registration Information:
Registration Version Number 1
Registration Date: 2011-06-22
Registrant of the namespace:
European Committee for Academic Middleware (ECAM)
Trans-European Research and Education Networking Association
(TERENA)
Singel
Amsterdam
The Netherlands
Designated contacts:
Contact: Licia Florio
Affiliation: TERENA
Singel 468 D
Amsterdam, 1017 AW
The Netherlands
EMail: florio@terena.org
Phone: +31(0)20 5304488
Contact: Victoriano Giralt
Affiliation: University of Malaga
Central ICT Services
Blvd. Louis Pasteur, 33
Campus de Teatinos
29071 Malaga
Spain
EMail: victoriano@uma.es
Phone: +34 95 213 1415
Giralt & McDuff Informational [Page 3]RFC 6338 SCHAC URN Namespace August 2011
Syntactic structure:
The Namespace Specific Strings (NSSs) of all URNs assigned by
SCHAC will conform to the syntax defined in Section 2.2 of
RFC 2141, "URN Syntax" [11]. In addition, all SCHAC 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 "Identifier assignment" section below for more on the
semantics of NSSs. This syntax convention is captured in the
following normative ABNF rules for SCHAC NSSs (see RFC 5234 [2]):
SCHAC-NSS = 1*subStChar *( ":" 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
SCHAC NSS is also a valid RFC 2141 NSS.
Relevant ancillary documentation:
None.
Identifier uniqueness:
It is the responsibility of TERENA 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 its branch of the naming tree.
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Identifier persistence:
TERENA bears ultimate responsibility for maintaining the usability
of SCHAC 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 the case where a subordinate
naming authority ceases to function.
Identifier assignment:
TERENA will create an initial series of immediately subordinate
naming authorities, and will define a process for adding to that
list of authorities. Such a list, and the policy for adding to
it, will be published at the root registry page. Each country
with a representative in SCHAC will be invited to designate a
naming authority. Country-specific namespaces based on the
country Internet Top-Level Domain (TLD) [12] will then be assigned
to the designated authority. The subordinated namespaces int and
eu will remain under TERENA authority, controlled by the SCHAC
activity members, for entities of global, international, or
European interest. There is also the possibility of granting
subordinate namespaces to multi-country organizations; in this
case, the organizational Internet Fully Qualified Domain Name
(FQDN) will be used as the prefix.
As an example, a European-level interest entity would be any value
related to information used in the Higher Education European
Space, or the so-called Bologna process. Such entities will
belong in the eu subordinate namespace.
Global international entities could encompass values related to
the Grid community or values useful both for some European and for
some Australian universities. Such entities would belong in the
int subordinate namespace.
Examples of multi-country organizations include TERENA itself or
an association like the Educational Policy Institute (EPI)
(educationalpolicy.org) that has members from Australia, Canada,
and the US.
URNs intended for values of SCHAC attributes will include the
attribute name immediately after the NSS prefix, before any
geographical namespace delegation, such that any string can convey
information about the attribute for which it is a value. For
example, values for schacUserStatus will be of the form:
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urn:schac:userStatus:int
urn:schac:userStatus:au or
urn:schac:userStatus:terena.org
If at all possible, automated registry publication mechanisms will
be provided, based on the work on distributed URN registries done
by the TF-EMC2 task force members.
Institutions and communities affiliated with SCHAC participants
may request that they be granted subordinate naming authority
status. Uniqueness of these namespaces under country authority
will be based on the requestor's Internet FQDN. This
subordination procedure SHOULD be carried along the delegation
chain; i.e., if at all possible, all entities that receive a
delegated namespace MUST have a valid FQDN and MUST publish an
Internet accessible URN value registry, based on the URN registry
mechanisms designed by the TF-EMC2 task force members.
On at least an annual basis, TERENA 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 TERENA. 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 SCHAC Namespace Specific Strings (NSSs)
is defined below as an exact, case-sensitive string match. TERENA
will assign names of immediately subordinate naming authorities in
lowercase only. This forestalls the registration of two SCHAC-
subordinate naming authorities whose names differ only in case.
Attribute names will use the same mixed-case format as in the
schema definition.
Identifier resolution:
The namespace is not currently listed with a Resolution Discovery
System (RDS), but nothing about the namespace prohibits the future
definition of appropriate resolution methods or listing with
an RDS.
TERENA will maintain a registry of all SCHAC-assigned URN values,
both final and for delegation, on its web site:
https://urnreg.terena.org/
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Delegation entries will have a pointer to the registry of the
subordinate naming authority. This SHOULD recurse down the
delegation tree, but registries for several delegated namespaces
MAY be maintained by a single naming authority.
All registries MUST publish their URNs over https links [3]. The
https links MUST be secured by sites offering credentials signed
by a SCHAC-community recognized Certification Authority (CA) using
the latest secure methods for accessing a web site (which at
present is the latest version of Transport Layer Security (TLS)
[4]). Registries SHOULD consider the user interface implications
of their choice of CA, taking into account issues like browser
alerts and blind trust.
Lexical equivalence:
Lexical equivalence of two SCHAC Namespace Specific Strings (NSSs)
is defined as an exact, case-sensitive string match.
Conformance with URN syntax:
All SCHAC NSSs fully conform to RFC 2141 syntax rules for NSSs.
Validation mechanism:
As specified in the "Identifier resolution" section above, TERENA
will maintain an index of all SCHAC-assigned URNs on its web site:
https://urnreg.terena.org/. Presence in that registry or in any
subordinate registry implies that a given URN is valid. Delegated
naming authorities MUST guarantee that values are valid in their
assigned spaces.
Scope:
Global.
4. Examples
The following examples are not guaranteed to be real. They are
listed for pedagogical reasons only.
urn:schac:personalUniqueID:es:DNI:9999999Z
urn:schac:personalUniqueCode:es:uma.es:codUni:061696758X
urn:schac:userStatus:au:uq.edu.au:service:mail:receive:disabled
urn:schac:personalPosition:pl:umk.pl:programmer
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5. Security Considerations
There are no additional security considerations beyond those normally
associated with the use and resolution of URNs in general.
In order to guarantee the validity and origin of SCHAC-NSS URN
values, they MUST be published over https links [3]. The https links
MUST be secured by sites offering credentials signed by a SCHAC-
community recognized Certification Authority (CA) using the latest
secure methods for accessing a web site (which at present is the
latest version of TLS [4]).
6. Namespace Considerations
Registration of a Namespace Identifier (NID) specific to SCHAC is
reasonable given the following considerations:
SCHAC would like to assign URNs to some very fine-grained objects.
This does not seem to be the primary intended use of the XML.org
namespace (RFC 3120) [13], or the more tightly controlled
Organization for the Advancement of Structured Information
Standards (OASIS) [14] namespace (RFC 3121) [15].
SCHAC seeks naming autonomy. SCHAC is not a member of OASIS, so
becoming a subordinate naming authority under the OASIS URN space
is not an option. There is the MACE (Middleware Architecture
Committee for Education) (RFC 3613) [16] namespace, but the SCHAC
development is done outside of the MACE activity scope; thus, the
attributes and values do not belong in the MACE namespace. Using
the MACE namespace requires that the SCHAC namespace be placed
under one of the SCHAC participants' namespaces, which hinders its
global scope.
SCHAC will want to assign URNs to non-XML objects as well. That
is another reason that XML.org may not be an appropriate higher-
level naming authority for SCHAC.
Some of the already defined SCHAC attribute values have been assigned
URNs under the urn:mace:terena.org namespace. These values will
enter a deprecation cycle, with a clear indication that they will be
replaced by values under the new namespace once it is assigned. In
any case, RFC 3406 [5] (which replaced RFC 2611) includes an explicit
statement that two or more URNs may point to the same resource.
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7. Community Considerations
The assignment and use of identifiers within the namespace are open,
and the related rule is established by the SCHAC activity members.
Registration agencies (the next-level naming authorities) will be the
National Research and Education Networks (NRENs) and established
organizational cross-border organizations that participate in SCHAC.
It is expected that the majority of the European NRENs, their
constituencies, participants in the Australian Access Federation, and
some other international activities will make use of the SCHAC
namespace.
After the establishment of the SCHAC namespace, TERENA will establish
a registry service (analogously to other distributed pan-European
services, such as eduroam, PerfSONAR, etc.) for the namespace
clients. This registry will be available via the root page of the
namespace: https://urnreg.terena.org/. The policy for registrations
will be defined in documents available at the root page of the
registry.
8. IANA Considerations
In accordance with BCP 66 [5], IANA has registered the Formal URN
Namespace 'schac' in the Registry of URN Namespaces, using the
registration template presented in Section 2 of this document.
9. Acknowledgments
SCHAC is the result of the TERENA TF-EMC2 task force and many others
that have contributed ideas to the development of the schema.
This document was discussed on the URN-NID list, with the special
help of Alfred Hoenes, who thoroughly reviewed the document, helped
us correct errors, and suggested clarifications to the text.
Peter Saint-Andre has also provided comments that have improved the
overall document quality, for which we herein thank him. We'd also
like to thank Chris Lonvick for helping us express our security
concerns in a better way. Finally, we thank other reviewers that
have helped us to give the final touches to the text.
Special thanks should go to Dyonisius Visser from the TERENA
technical team for taking the time and effort required to set up the
root instance of the namespace registry.
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RFC 6338 SCHAC URN Namespace August 2011
10. References
10.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Crocker, D., Ed., and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[3] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[4] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS)
Protocol Version 1.2", RFC 5246, August 2008.
[5] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"Uniform Resource Names (URN) Namespace Definition Mechanisms",
BCP 66, RFC 3406, October 2002.
10.2. Informative References
[6] TERENA, "Trans-European Research and Education Networking
Association", <http://www.terena.org/>.
[7] TERENA TF-EMC2, "SCHAC activity web site",
<http://www.terena.org/activities/tf-emc2/schac.html>.
[8] Sciberras, A., Ed., "Lightweight Directory Access Protocol
(LDAP): Schema for User Applications", RFC 4519, June 2006.
[9] Smith, M., "Definition of the inetOrgPerson LDAP Object Class",
RFC 2798, April 2000.
[10] MACE-Dir, "eduPerson Object Class Specification",
December 2007, <http://middleware.internet2.edu/eduperson/docs/
internet2-mace-dir-eduperson-200712.html>.
[11] Moats, R., "URN Syntax", RFC 2141, May 1997.
[12] IANA, "Country TLDs", <http://www.iana.org/domains/root/db/>.
[13] Best, K. and N. Walsh, "A URN Namespace for XML.org", RFC 3120,
June 2001.
[14] OASIS, "Organization for the Advancement of Structured
Information Standards: OASIS", <http://www.oasis-open.org/>.
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[15] Best, K. and N. Walsh, "A URN Namespace for OASIS", RFC 3121,
June 2001.
[16] Morgan, R. and K. Hazelton, "Definition of a Uniform Resource
Name (URN) Namespace for the Middleware Architecture Committee
for Education (MACE)", RFC 3613, October 2003.
Authors' Addresses
Victoriano Giralt, M.D.
University of Malaga
Avd. Cervantes, 2
Malaga, Malaga E-29071
Spain
Phone: +34-95-213-1415
EMail: victoriano@uma.es
URI: http://www.uma.es/
Dr. Rodney McDuff
The University of Queensland
EMail: r.mcduff@uq.edu.au
URI: http://www.uq.edu.au/
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