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Namespace ID: urn-3
Registration Information:
Version 1
Date: 2001-02-27
Declared registrant of the namespace:
Name: Stephen Abrams
E-mail: nrsadm@hulmail.harvard.edu
Affiliation: Harvard University Library
Address: Office for Information Systems
1280 Massachusetts Avenue, Suite 404
Cambridge, MA 02138
The named registrant is specified in his capacity as the namespace
administrator for the Harvard University Library Office for
Information Systems (HUL/OIS). If the future, other individuals may
be designated by HUL/OIS for the purposes of administering potential
updates to this registration.
Declaration of syntactic structure:
All URNs defined under the namespace have the following structure,
specified in ABNF notation [1]:
urn = "urn:" nid ":" nss
nid = "urn-" n
n = number-assigned-by-IANA
nss = authoritypath ":" resourcename
authoritypath = authority / (authoritypath "." authority)
authority = 1*authoritychar
authoritychar = upper / lower / number /
"(" / ")" / "+" / "," / "-" / "=" / "@" /
";" / "$" / "_" / "!" / "*" / "'" / ("%" hex hex)
resourcename = 1*resourcechar
resourcechar = authoritychar / "." / ":"
where <upper>, <lower>, <number>, and <hex> are defined in Section
2.2 of [4].
The %-escaping mechanism, as described in Sections 2.2 and 2.3.1 of
[4], is used to incorporate into URNs characters that are not
explicitly allowed by the grammar.
Examples of valid URNs defined under the namespace include:
urn:urn-<n>:FHCL:10403
urn:urn-<n>:HBS.Baker.TC:1923
urn:urn-<n>:HUL.Eresource:holliswb
urn:urn-<n>:HUL.OIS:Home
The <authoritypath> component of the URN uniquely identifies the
naming authority under which the URN was assigned. A naming
authority is an administrative unit or agent that has been granted
the privilege of creating, and the responsibility for maintaining
persistently, names in the subset of the full namespace identified
by that authority's <authoritypath>.
Naming authorities exist within a tree-like structure of authority
delegation, under which any given naming authority derives its
privileges and responsibilities from a pre-existing parent
authority. Naming authorities may independently propose and enforce
local policies and administrative procedures relative to names
created within their scope.
The administrator of a naming authority, regardless of its position
within the delegation tree, has full oversight and operational
control over all aspects of URN administration of all delegated
authorities that derive from the common parent. The root naming
authority for the namespace is administered by HUL/OIS. The root
authority exists solely to provide a common root of delegatable
naming authority; it alone has no corresponding <authoritypath>.
Relevant ancillary documentation:
[1] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[2] Daniel, R., "A Trivial Convention for Using HTTP in URN
Resolution", RFC 2169, June 1997.
[3] Mealling, M. and R. Daniel, Jr., "URI Resolution Services
Necessary for URN Resolution", RFC 2483, January 1999.
[4] Moats, R. "URN Syntax", RFC 2141, May 1997.
[5] Shafer, K., S. Weibel, E. Jul, and J. Fausey, "Introduction
to Persistent Uniform Resource Locators", Proc. INET '96, The
Internet: Transforming Our Society Now, Montreal, June 24-28,
1996.
Identifier uniqueness considerations:
Individual naming authorities are responsible for insuring the
uniqueness of the <resourcename> components of the URNs created
within their scope. Naming authorities are also responsible for
insuring the uniqueness of the terminal <authority> component of the
<authoritypath> for all delegated authorities.
Identifier persistence considerations:
HUL provides an administrative system that maintains URN
registration within the namespace. The system insures that once a
URN is assigned it is never reassigned to a different resource.
Process of identifier assignment:
The administrative system is decentralized to allow individual
naming authorities to create and maintain independently the URNs
that fall within the scope of those authorities.
Administrative units or agents wishing to assign URNs must be
granted the appropriate privilege to do so from the administrator of
the naming authority in the scope of which the URNs are to be
created. Similarly, units or agents wishing to administer a new
delegated naming authority must negotiate directly with the
administrator of the potential parent authority, who, if
acquiescent, will create the delegated authority.
Process for identifier resolution:
HUL provides a resolution service for the namespace. The service
accepts THTTP-formatted [2] resolution requests for the URN-to-URL
and URN-to-URLs services (specified by either the "N2L" and "N2Ls"
mnemonics of [2] or the "I2L" and "I2Ls" mnemonics of [3]). Server
responses are consistent with [3].
Multiple URLs associated with a single URN are maintained within the
resolver database in an ordered list. A URN-to-URL request against
a URN with multiple URLs returns the URL with the highest priority
in the list.
The mechanism used by client user agents to determine the location
of the resolution service is outside of the scope of this
registration document.
In the absence of widely available native support for URNs within
the current generation of web clients, the resolution service also
accepts requests in a PURL-like syntax [5] for URNs that are
encapsulated into URLs:
http://<resolver>/urn-<n>:<authoritypath>:<resourcename>
In this case, the URN-to-URL resolution service is assumed by the
resolver.
Rules for Lexical Equivalence: The entire URN is case-insensitive.
Conformance with URN syntax: No special considerations.
Validation mechanism:
The administrative system performs syntactic validation of all URNs
at the point of their registration.
Scope:
This namespace is used for the identification of network-accessible
resources delivered to the Harvard community and the public through
the mediation of HUL-supported systems or other delivery mechanisms
controlled or directed by Harvard-affiliated entities whose
standards and procedures for resource maintenance and access are
consistent with those of HUL, or for resources made accessible to
the Harvard community under contractual or similar arrangements.
These resources are provided by various organizational units of
Harvard University, including administrative and academic
departments, libraries, and museums, as well as digital content
purchased or licensed from external vendors.
(02/28/01)
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