Network Working Group V. Giralt
Internet-Draft Univ. Malaga
Intended status: Standards Track R. McDuff
Expires: August 18, 2011 Univ. Queensland
February 14, 2011
Definition of a Uniform Resource Name (URN) Namespace for the Schema for
Academia (SCHAC)
draft-giralt-schac-ns-03
Abstract
This document describes a Uniform Resource Name (URN) namespace for
the Schema for Academia (SCHAC).
This namespace is for naming persistent resources defined by the
SCHAC international activity participants, their working groups and
other designated subordinates. The main use will be the creation of
controlled vocabulary values for attributes in the SCHAC schema.
These values will be associated to particular instances of persons or
objects belonging to any of the SCHAC object classes.
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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].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on August 18, 2011.
Copyright Notice
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document authors. All rights reserved.
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1. Introduction
The Schema for Academia (SCHAC) international activity was born
inside the TF-EMC2 middleware task force of the Trans European
Research and Education Network Association (TERENA)[4]. The initial
aim of SCHAC was to harmonise 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 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[5].
SCHAC does not supplant other person schemas such as
organizationalPerson [6], inetOrgPerson [7] or eduPerson [8], it
extends those where needed for the purposes of Higher Education
outside the United States. This characteristic has made SCHAC,
originally an European effort, useful for groups outside Europe.
This namespace is for naming persistent resources defined by the
SCHAC international activity participants, their working groups and
other designated subordinates. The main use will be the creation of
controlled vocabulary values for attributes in the SCHAC schema.
These values will be associated to particular instances of persons or
objects belonging to any of the SCHAC object classes.
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2. Specification Template
Namespace ID:
schac
Registration Information:
Registration Version Number 1
Registration Date: YYYY-MM-DD [RFC Editor, please replace with the
date of approval of this document for publication as an RFC]
Registrant of the namespace:
European Committee for Academic Middleware
Trans European Research and Education Network 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 2366
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Syntactic structure:
The Namespace Specific Strings (NSS) of all URNs assigned by SCHAC
will conform to the syntax defined in section 2.2 of RFC 2141,
"URN Syntax"[9]. 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 section below entitled "Identifier assignment" 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 their 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 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. Each country with a representative in SCHAC
will be invited to designate a naming authority. Country specific
namespaces based on the country Internet TLD [10] will be assigned
then 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 FQDN will be used as prefix.
As an example, an 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 comunity or values useful both for some European and
Australian universities. Such entities would belong in the int
subordinate namespace.
Examples of multicountry organizations include TERENA itself or an
association like 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 from:
urn:schac:UserStatus:int
urn:schac:UserStatus:au or
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urn:schac:UserStatus:terena.org
Automated registry publication mechanisms will be provided if at
all possible, 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., all entities that receive a delegated namespace MUST
have a valid FQDN and MUST publish an Internet accessible URN
value registry, if at all possible 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://www.terena.org/urn
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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 an HTTPS link.
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://www.terena.org/urn. Presence in that registry or in any
subordinate one implies that a given URN is valid. Delegated
naming authorities MUST guarantee that values are valid in their
assigned spaces.
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.
In order to guarantee the validity and origin of SCHAC-NSS URN
values, they MUST be published over HTTPS links.
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4. Namespace Considerations
Registration of an 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 XMLORG
namespace (RFC 3120) [11], or the more tightly controlled OASIS
[12] namespace (RFC 3121) [13].
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 [12] namespace but the SCHAC
development is done outside MACE activity scope and thus the
attributes and values do not belong into the MACE namespace.
Using the MACE namespace requires the SCHAC namespace to be placed
under one of the SCHAC participants namespace, which hinders its
global scope.
SCHAC 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 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 clear indication of them being
replaced by values under the new namespace once it is assigned.
Anyhow, RFC 3406 [3] (which replaced RFC 2611) includes an explicit
statement that two or more URNs may point to the same resource.
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5. 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 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 make use of the SCHAC namespace.
After the establishment of the SCHAC namespace, TERENA will, as soon
as practical, establish a registry service (analogously to other
distributed pan-European services, like eduroam, PerfSONAR, etc.) for
the namespace clients.
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6. IANA Considerations
In accordance with BCP 66 [3], IANA is asked to register the Formal
URN Namespace 'schac' in the Registry of URN Namespaces, using the
registration template presented in Section 2 of this document.
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7. 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 has been discussed on the URN-NID list, with the
special help of Alfred Hoenes who has thoroughly reviewed the
documents and helped us correct errors and suggested clarifications
to the text.
Peter Saint-Andre has also provided comments that have improved the
overall document quality, which we herein thank him.
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8. References
8.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[3] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"Uniform Resource Names (URN) Namespace Definition Mechanisms",
BCP 66, RFC 3406, October 2002.
8.2. Informative References
[4] TERENA, "Trans European Research and Education Network
Assosiation".
[5] TERENA TF-EMC2, "SCHAC activity web site".
[6] Sciberras, A., "Lightweight Directory Access Protocol (LDAP):
Schema for User Applications", RFC 4519, June 2006.
[7] Smith, M., "Definition of the inetOrgPerson LDAP Object Class",
RFC 2798, April 2000.
[8] MACE-Dir, "eduPerson Object Class Specification",
December 2007.
[9] Moats, R., "URN Syntax", RFC 2141, May 1997.
[10] IANA, "Country TLDs".
[11] Best, K. and N. Walsh, "A URN Namespace for XML.org", RFC 3120,
June 2001.
[12] OASIS, "Organization for the Advancement of Structured
Information Standards: OASIS".
[13] Best, K. and N. Walsh, "A URN Namespace for OASIS", RFC 3121,
June 2001.
[14] Internet2, "Middleware Architecture Committee for Education:
MACE".
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Authors' Addresses
Victoriano Giralt M.D.
University of Malaga
Avd. Cervantes, 2
Malaga, Malaga E-29071
Spain
Phone: +34-95-213-2366
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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