RFC3406: Uniform Resource Names (URN) Namespace Definition Mechanisms
Download in PDF format Download in text format
Obsoletes:
RFC2611
Obsoleted By:
RFC8141
Network Working Group L. Daigle
Request for Comments: 3406 Thinking Cat Enterprises
BCP: 66 D.W. van Gulik
Obsoletes: 2611 WebWeaving
Category: Best Current Practice R. Iannella
IPR Systems
P. Faltstrom
Cisco
October 2002
Uniform Resource Names (URN) Namespace Definition Mechanisms
Status of this Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document lays out general definitions of and mechanisms for
establishing Uniform Resource Names (URN) "namespaces". The URN WG
has defined a syntax for URNs in RFC 2141, as well as some proposed
mechanisms for their resolution and use in Internet applications in
RFC 3401 and RFC 3405. The whole rests on the concept of individual
"namespaces" within the URN structure. Apart from proof-of-concept
namespaces, the use of existing identifiers in URNs has been
discussed in RFC 2288.
Table of Contents
1.0 Introduction ................................................. 2
2.0 What is a URN Namespace? ..................................... 3
3.0 URN Namespace (Registration) Types ........................... 3
3.1 Experimental Namespaces ..................................... 4
3.2 Informal Namespaces ......................................... 4
3.3 Formal Namespaces ........................................... 4
4.0 URN Namespace Registration, Update, and NID Assignment
Process ..................................................... 6
4.1 Experimental ................................................ 6
4.2 Informal .................................................... 6
4.3 Formal ...................................................... 7
5.0 Security Considerations ..................................... 9
Daigle, et. al. Best Current Practice [Page 1]
RFC 3406 URN Namespace Definition Mechanisms October 2002
6.0 IANA Considerations ......................................... 9
7.0 References .................................................. 9
Appendix A -- URN Namespace Definition Template ................. 11
Appendix B -- Illustration ...................................... 15
B.1 Example Template ............................................ 15
B.2 Registration steps in practice .............................. 17
Appendix C -- Changes from RFC 2611 ............................. 18
C.1 Detailed Document Changes ................................... 19
Authors' Addresses .............................................. 21
Full Copyright Statement ........................................ 22
1.0 Introduction
Uniform Resource Names (URNs) are resource identifiers with the
specific requirements for enabling location independent
identification of a resource, as well as longevity of reference.
URNs are part of the larger Uniform Resource Identifier (URI) family
[RFC3305] with the specific goal of providing persistent naming of
resources.
There are 2 assumptions that are key to this document:
Assumption #1:
Assignment of a URN is a managed process.
I.e., not all strings that conform to URN syntax are necessarily
valid URNs. A URN is assigned according to the rules of a
particular namespace (in terms of syntax, semantics, and process).
Assumption #2:
The space of URN namespaces is managed.
I.e., not all syntactically correct URN namespaces (per the URN
syntax definition) are valid URN namespaces. A URN namespace must
have a recognized definition in order to be valid.
The purpose of this document is to outline a mechanism and provide a
template for explicit namespace definition, as well as provide the
mechanism for associating an identifier (called a "Namespace ID", or
NID) which is registered with the Internet Assigned Numbers Authority
(IANA).
Note that this document restricts itself to the description of
processes for the creation of URN namespaces. If "resolution" of any
so-created URN identifiers is desired, a separate process of
registration in a global NID directory, such as that provided by the
Daigle, et. al. Best Current Practice [Page 2]
RFC 3406 URN Namespace Definition Mechanisms October 2002
DDDS system [RFC3401], is necessary. See [RFC3405] for information
on obtaining registration in the DDDS global NID directory.
2.0 What is a URN Namespace?
For the purposes of URNs, a "namespace" is a collection of uniquely-
assigned identifiers. That is, the identifiers are not ever assigned
to more than 1 resource, nor are they ever re-assigned to a different
resource. A single resource, however, may have more than one URN
assigned to it for different purposes. A URN namespace itself has an
identifier in order to:
- ensure global uniqueness of URNs
- (where desired) provide a cue for the structure of the
identifier
For example, many identifier systems may use strings of numbers as
identifiers (e.g., ISBN, ISSN, phone numbers). It is conceivable
that there might be some numbers that are valid identifiers in two
different established identifier systems. Using different
designators for the two collections ensures that no two URNs will be
the same for different resources (since each collection is required
to uniquely assign each identifier).
The development of an identifier structure, and thereby a collection
of identifiers, is a process that is inherently dependent on the
requirements of the community defining the identifier, how they will
be assigned, and the uses to which they will be put. All of these
issues are specific to the individual community seeking to define a
namespace (e.g., publishing community, association of booksellers,
protocol developers, etc); they are beyond the scope of the IETF URN
work.
This document outlines the processes by which a collection of
identifiers satisfying certain constraints (uniqueness of assignment,
etc) can become a bona fide URN namespace by obtaining a NID. In a
nutshell, a template for the definition of the namespace is completed
for deposit with IANA, and a NID is assigned. The details of the
process and possibilities for NID strings are outlined below.
3.0 URN Namespace (Registration) Types
There are three categories of URN namespaces defined here,
distinguished by expected level of service and required procedures
for registration. Registration processes for each of these namespace
types are given in Section 4.0.
Daigle, et. al. Best Current Practice [Page 3]
RFC 3406 URN Namespace Definition Mechanisms October 2002
3.1 Experimental Namespaces
These are not explicitly registered with IANA. They take the form:
X-<NID>
No provision is made for avoiding collision of experimental NIDs;
they are intended for use within internal or limited experimental
contexts.
3.2 Informal Namespaces
These are fully fledged URN namespaces, with all the rights and
requirements associated thereto. Informal namespaces can be
registered in global registration services. They are required to
uphold the general principles of a well-managed URN namespace --
providing persistent identification of resources, and unique
assignment of identifier strings. Informal and formal namespaces
(described below) differ in the NID assignment. IANA will assign an
alphanumeric NID to registered informal namespaces, per the process
outlined in Section 4.0.
3.3 Formal Namespaces
A formal namespace may be requested, and IETF review sought, in cases
where the publication of the NID proposal and the underlying
namespace will provide benefit to some subset of users on the
Internet. That is, a formal NID proposal, if accepted, must be
functional on and with the global Internet, not limited to users in
communities or networks not connected to the Internet. For example,
a NID that is meant for naming of physics research is requested. If
that NID request required that the user use a proprietary network or
service that was not at all open to the general Internet user, then
it would make a poor request for a formal NID. The intent is that,
while the community of those who may actively use the names assigned
within that NID may be small (but no less important), the potential
use of names within that NID is open to any user on the Internet.
It is expected that Formal NIDs may be applied to namespaces where
some aspects are not fully open. For example, a namespace may make
use of a fee-based, privately managed, or proprietary registry for
assignment of URNs in the namespace, but it may still provide benefit
to some Internet users if the services associated have openly-
published access protocols.
Daigle, et. al. Best Current Practice [Page 4]
RFC 3406 URN Namespace Definition Mechanisms October 2002
In addition to the basic registration information defined in the
registration template (in Appendix A), a formal namespace request
must be accompanied by documented considerations of the need for a
new namespace and of the community benefit from formally establishing
the proposed URN namespace.
Additionally, since the goal of URNs is to provide persistent
identification, some consideration as to the longevity and
maintainability of the namespace must be given. The URN WG discussed
at length the issue of finding objective measures for predicting (a
priori) the continued success of a namespace. No conclusion was
reached -- much depends on factors that are completely beyond the
technical scope of the namespace. However, the collective experience
of the IETF community does contain a wealth of information on
technical factors that will prevent longevity of identification. The
IESG may elect not to publish a proposed namespace RFC if the IETF
community consensus is that it contains technical flaws that will
prevent (or seriously impair the possibility of) persistent
identification.
The kinds of things the URN WG discussed included:
- the organization maintaining the URN namespace should
demonstrate stability and the ability to maintain the URN
namespace for a long time, and/or it should be clear how the
namespace can continue to be usable/useful if the organization
ceases to be able to foster it;
- it should demonstrate ability and competency in name assignment.
This should improve the likelihood of persistence (e.g. to
minimize the likelihood of conflicts);
- it should commit to not re-assigning existing names and
allowing old names to continue to be valid, even if the owners
or assignees of those names are no longer members or customers
of that organization. This does not mean that there must be
resolution of such names, but that they must not resolve the
name to false or stale information, and that they must not be
reassigned.
These aspects, though hard to quantify objectively, should be
considered by organizations/people considering the development of a
Formal URN namespace, and they will be kept in mind when evaluating
the technical merits of any proposed Formal namespace.
Daigle, et. al. Best Current Practice [Page 5]
RFC 3406 URN Namespace Definition Mechanisms October 2002
4.0 URN Namespace Registration, Update, and NID Assignment Process
Different levels of disclosure are expected/defined for namespaces.
According to the level of open-forum discussion surrounding the
disclosure, a URN namespace may be assigned or may request a
particular identifier. The "IANA Considerations" document [RFC2434]
suggests the need to specify update mechanisms for registrations --
who is given the authority to do so, from time to time, and what are
the processes. Since URNs are meant to be persistently useful, few
(if any) changes should be made to the structural interpretation of
URN strings (e.g., adding or removing rules for lexical equivalence
that might affect the interpretation of URN IDs already assigned).
However, it may be important to introduce clarifications, expand the
list of authorized URN assigners, etc, over the natural course of a
namespace's lifetime. Specific processes are outlined below.
The official list of registered URN namespaces is maintained by IANA.
URN namespace registrations are currently being posted in the
anonymous FTP directory:
http://www.iana.org/assignments/urn-namespaces
See [RFC3232] for the current location of IANA registry.
The registration and maintenance procedures vary slightly from one
namespace type (as defined in Section 3.0) to another.
4.1 Experimental
These are not explicitly registered with IANA. They take the form:
X-<NID>
No provision is made for avoiding collision of experimental NIDs;
they are intended for use within internal or limited experimental
contexts.
As there is no registration, no registration maintenance procedures
are needed.
4.2 Informal
These are registered with IANA and are assigned a number sequence as
an identifier, in the format:
"urn-" <number>
Daigle, et. al. Best Current Practice [Page 6]
RFC 3406 URN Namespace Definition Mechanisms October 2002
where <number> is chosen by the IANA on a First Come First Served
basis (see [RFC2434]).
Registrants should send a copy of the registration template (see
Appendix A), duly completed, to:
urn-nid@apps.ietf.org
and allow for a 2 week discussion period for clarifying the
expression of the registration information and suggestions for
technical improvements to the namespace proposal.
After suggestions for clarification of the registration information
have been incorporated, the template may be submitted for assignment
of a NID to:
iana@iana.org
The only restrictions on <number> are that it consist strictly of
digits and that it not cause the NID to exceed length limitations
outlined in the URN syntax ([RFC2141]).
Registrations may be updated by the original registrant, or an entity
designated by the registrant, by updating the registration template,
submitting it to the discussion list for a further 2 week discussion
period, and finally resubmitting it to IANA, as described above.
4.3 Formal
Formal NIDs are assigned via IETF Consensus, as defined in [RFC2434]:
"IETF Consensus - New values are assigned through the IETF
consensus process. Specifically, new assignments are made via
RFCs approved by the IESG. Typically, the IESG will seek input on
prospective assignments from appropriate persons (e.g., a relevant
Working Group if one exists)."
Thus, the Formal NID application is made via publication of an RFC
through standard IETF processes. The RFC need not be standards-
track, but it will be subject to IESG review and acceptance pursuant
to the guidelines written here (as well as standard RFC publication
guidelines). The template defined in Appendix A may be included as
part of an RFC defining some other aspect of the namespace, or it may
be put forward as an RFC in its own right. The proposed template
should be sent to the:
urn-nid@apps.ietf.org
Daigle, et. al. Best Current Practice [Page 7]
RFC 3406 URN Namespace Definition Mechanisms October 2002
mailing list to allow for a two week discussion period for clarifying
the expression of the registration information, before the IESG
reviews the document.
The RFC must include a "Namespace Considerations" section, which
outlines the perceived need for a new namespace (i.e., where existing
namespaces fall short of the proposer's requirements).
Considerations might include:
- URN assignment procedures
- URN resolution/delegation
- type of resources to be identified
- type of services to be supported
NOTE: It is expected that more than one namespace may serve the same
"functional" purpose; the intent of the "Namespace Considerations"
section is to provide a record of the proposer's "due diligence" in
exploring existing possibilities, for the IESG's consideration.
The RFC must also include a "Community Considerations" section, which
indicates the dimensions upon which the proposer expects its
community to be able to benefit by publication of this namespace as
well as how a general Internet user will be able to use the space if
they care to do so. Potential considerations include:
- open assignment and use of identifiers within the namespace
- open operation of resolution servers for the namespace (server)
- creation of software that can meaningfully resolve and access
services for the namespace (client)
The RFC must include an "IANA Considerations" section, indicating
that the document includes a URN NID registration that is to be
entered into the IANA registry of URN NIDs.
A particular NID string is requested, and is assigned by IETF
consensus (as defined in [RFC2434]), with the additional constraints
that the NID string must:
- not be an already-registered NID
- not start with "x-" (see Type I above)
- not start with "urn-" (see Type II above)
- not start with "XY-", where XY is any combination of 2 ASCII
letters (see NOTE, below)
- be more than 2 letters long
Daigle, et. al. Best Current Practice [Page 8]
RFC 3406 URN Namespace Definition Mechanisms October 2002
NOTE: ALL two-letter combinations, and two-letter combinations
followed by "-" and any sequence of valid NID characters are reserved
for potential use as countrycode-based NIDs for eventual national
registrations of URN namespaces. The definition and scoping of rules
for allocation of responsibility for such namespaces is beyond the
scope of this document.
Registrations may be revised by updating the RFC through standard
IETF RFC update processes (see [RFC2606] for a discussion of IETF
process). In any case, a revised document, in the form of a new
Internet-Draft, must be published, and the proposed updated template
must be circulated on the urn-nid discussion list, allowing for a 2
week review period before pursuing publication of the new RFC
document.
5.0 Security Considerations
This document largely focuses on providing mechanisms for the
declaration of public information. Nominally, these declarations
should be of relatively low security profile, however there is always
the danger of "spoofing" and providing mis-information. Information
in these declarations should be taken as advisory.
6.0 IANA Considerations
This document outlines the processes for registering URN namespaces,
and has implications for the IANA in terms of registries to be
maintained. In all cases, the IANA should assign the appropriate NID
(informal or formal), as described above, once an IESG-designated
expert has confirmed that the requisite registration process steps
have been completed. This document defines processes to replace
those outlined in [RFC2611].
7.0 References
[ISO8601] ISO 8601 : 1988 (E), "Data elements and interchange formats
- Information interchange - Representation of dates and
times"
[RFC1737] Sollins, K. and L. Masinter, "Functional Requirements for
Uniform Resource Names", RFC 1737, December 1994.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997.
Daigle, et. al. Best Current Practice [Page 9]
RFC 3406 URN Namespace Definition Mechanisms October 2002
[RFC2276] Sollins, K., "Architectural Principles of Uniform Resource
Name Resolution", RFC 2276, January 1998.
[RFC2288] Lynch, C., Preston, C. and R. Daniel, "Using Existing
Bibliographic Identifiers as Uniform Resource Names", RFC
2288, February 1998.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC2611] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom,
"URN Namespace Definition Mechanisms", RFC 2611, June 1999.
[RFC3232] Reynolds, J, Editor, "Assigned Numbers: RFC 1700 is
Replaced by an On-line Database", RFC 3232, January 2002.
[RFC3305] Mealling, M. (Ed.) and R. Denenberg (Ed.), "Report from the
Joint W3C/IETF URI Planning Interest Group: Uniform
Resource Identifiers (URIs), URLs, and Uniform Resource
Names (URNs): Clarifications and Recommendations", RFC
3305, August 2002.
[RFC3401] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part One: The Comprehensive DDDS", RFC 3401, October 2002.
[RFC3405] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part Five: URI.ARPA Assignment Procedures", RFC 3405,
October 2002.
Daigle, et. al. Best Current Practice [Page 10]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Appendix A -- URN Namespace Definition Template
Definition of a URN namespace is accomplished by completing the
following information template. Apart from providing a mechanism for
disclosing structure of the URN namespace, this information is
designed to be useful for
- entities seeking to have a URN assigned in a namespace (if
applicable)
- entities seeking to provide URN resolvers for a namespace (if
applicable)
This is particularly important for communities evaluating the
possibility of using a portion of an existing URN namespace rather
than creating their own.
Applications for Formal URN namespaces must also document "Namespace
Considerations", "Community Considerations" and "IANA
Considerations", as described in Section 4.3.
Information in the template is as follows:
Namespace ID:
Assigned by IANA. In the case of a Formal NID registration, a
particular NID string may be requested.
Registration Information:
This is information to identify the particular version of
registration information:
- registration version number: starting with 1, incrementing by 1
with each new version
- registration date: date submitted to the IANA, using the format
outlined in [ISO8601]:
YYYY-MM-DD
Declared registrant of the namespace:
This includes:
Registering organization
Name
Address
Designated contact person
Name
Coordinates (at least one of: e-mail, phone, postal address)
Daigle, et. al. Best Current Practice [Page 11]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Declaration of syntactic structure:
This section should outline any structural features of identifiers
in this namespace. At the very least, this description may be
used to introduce terminology used in other sections. This
structure may also be used for determining realistic
caching/shortcuts approaches; suitable caveats should be provided.
If there are any specific character encoding rules (e.g., which
character should always be used for single-quotes), these should
be listed here.
Answers might include, but are not limited to:
- the structure is opaque (no exposition)
- a regular expression for parsing the identifier into
components, including naming authorities
Relevant ancillary documentation:
This section should list any RFCs, standards, or other published
documentation that defines or explains all or part of the
namespace structure.
Answers might include, but are not limited to:
- RFCs outlining syntax of the namespace
- Other of the defining community's (e.g., ISO) documents
outlining syntax of the identifiers in the namespace
- Explanatory material introducing the namespace
Identifier uniqueness considerations:
This section should address the requirement that URN identifiers
be assigned uniquely -- they are assigned to at most one resource,
and are not reassigned.
(Note that the definition of "resource" is fairly broad; for
example, information on "Today's Weather" might be considered a
single resource, although the content is dynamic.)
Possible answers include, but are not limited to:
- exposition of the structure of the identifiers, and
partitioning of the space of identifiers amongst assignment
authorities which are individually responsible for respecting
uniqueness rules
- identifiers are assigned sequentially
- information is withheld; the namespace is opaque
Daigle, et. al. Best Current Practice [Page 12]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Identifier persistence considerations:
Although non-reassignment of URN identifiers ensures that a URN
will persist in identifying a particular resource even after the
"lifetime of the resource", some consideration should be given to
the persistence of the usability of the URN. This is particularly
important in the case of URN namespaces providing global
resolution.
Possible answers include, but are not limited to:
- quality of service considerations
Process of identifier assignment:
This section should detail the mechanisms and/or authorities for
assigning URNs to resources. It should make clear whether
assignment is completely open, or if limited, how to become an
assigner of identifiers, and/or get one assigned by existing
assignment authorities.
Answers could include, but are not limited to:
- assignment is completely open, following a particular algorithm
- assignment is delegated to authorities recognized by a
particular organization (e.g., the Digital Object Identifier
Foundation controls the DOI assignment space and its
delegation)
- assignment is completely closed (e.g., for a private
organization)
Process for identifier resolution:
If a namespace is intended to be accessible for global resolution,
it must be registered in an RDS (Resolution Discovery System, see
[RFC2276]) such as DDDS. Resolution then proceeds according to
standard URI resolution processes, and the mechanisms of the RDS.
What this section should outline is the requirements for becoming
a recognized resolver of URNs in this namespace (and being so-
listed in the RDS registry).
Answers may include, but are not limited to:
- the namespace is not listed with an RDS; this is not relevant
- resolution mirroring is completely open, with a mechanism for
updating an appropriate RDS
- resolution is controlled by entities to which assignment has
been delegated
Daigle, et. al. Best Current Practice [Page 13]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Rules for Lexical Equivalence:
If there are particular algorithms for determining equivalence
between two identifiers in the underlying namespace (hence, in the
URN string itself), rules can be provided here.
Some examples include:
- equivalence between hyphenated and non-hyphenated groupings in
the identifier string
- equivalence between single-quotes and double-quotes
- Namespace-defined equivalences between specific characters,
such as "character X with or without diacritic marks".
Note that these are not normative statements for any kind of best
practice for handling equivalences between characters; they are
statements limited to reflecting the namespace's own rules.
Conformance with URN Syntax:
This section should outline any special considerations required
for conforming with the URN syntax. This is particularly
applicable in the case of legacy naming systems that are used in
the context of URNs.
For example, if a namespace is used in contexts other than URNs,
it may make use of characters that are reserved in the URN syntax.
This section should flag any such characters, and outline
necessary mappings to conform to URN syntax. Normally, this will
be handled by hex encoding the symbol.
For example, see the section on SICIs in [RFC2288].
Validation mechanism:
Apart from attempting resolution of a URN, a URN namespace may
provide mechanisms for "validating" a URN -- i.e., determining
whether a given string is currently a validly-assigned URN. There
are 2 issues here: 1) users should not "guess" URNs in a
namespace; 2) when the URN namespace is based on an existing
identifier system, it may not be the case that all the existing
identifiers are assigned on Day 0. The reasonable expectation is
that the resource associated with each resulting URN is somehow
related to the thing identified by the original identifier system,
but those resources may not exist for each original identifier.
For example, even if a telephone number-based URN namespace was
created, it is not clear that all telephone numbers would
Daigle, et. al. Best Current Practice [Page 14]
RFC 3406 URN Namespace Definition Mechanisms October 2002
immediately become "valid" URNs, that could be resolved using
whatever mechanisms are described as part of the namespace
registration.
Validation mechanisms might be:
- a syntax grammar
- an on-line service
- an off-line service
Scope:
This section should outline the scope of the use of the
identifiers in this namespace. Apart from considerations of
private vs. public namespaces, this section is critical in
evaluating the applicability of a requested NID. For example, a
namespace claiming to deal in "social security numbers" should
have a global scope and address all social security number
structures (unlikely). On the other hand, at a national level, it
is reasonable to propose a URN namespace for "this nation's social
security numbers".
Appendix B -- Illustration
B.1 Example Template
The following example is provided for the purposes of illustrating
the URN NID template described in Appendix A. Although it is based
on a hypothetical "generic Internet namespace" that has been
discussed informally within the URN WG, there are still technical and
infrastructural issues that would have to be resolved before such a
namespace could be properly and completely described.
Namespace ID:
To be assigned
Registration Information:
Version 1
Date: <when submitted>
Daigle, et. al. Best Current Practice [Page 15]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Declared registrant of the namespace:
Name: Thinking Cat Enterprises
Address: 1 ThinkingCat Way
Trupville, NewCountry
Contact: L. Daigle
E-mail: leslie@thinkingcat.com
Declaration of structure:
The identifier structure is as follows:
URN:<assigned number>:<FQDN>:<assigned string>
where FQDN is a fully-qualified domain name, and the assigned
string is conformant to URN syntax requirements.
Relevant ancillary documentation:
Definition of domain names, found in:
P. Mockapetris, "DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION",
RFC 1035, November 1987.
Identifier uniqueness considerations:
Uniqueness is guaranteed as long as the assigned string is never
reassigned for a given FQDN, and that the FQDN is never
reassigned.
N.B.: operationally, there is nothing that prevents a domain name
from being reassigned; indeed, it is not an uncommon occurrence.
This is one of the reasons that this example makes a poor URN
namespace in practice, and is therefore not seriously being
proposed as it stands.
Identifier persistence considerations:
Persistence of identifiers is dependent upon suitable delegation
of resolution at the level of "FQDN"s, and persistence of FQDN
assignment.
Same note as above.
Daigle, et. al. Best Current Practice [Page 16]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Process of identifier assignment:
Assignment of these URNs is delegated to individual domain name
holders (for FQDNs). The holder of the FQDN registration is
required to maintain an entry (or delegate it) in the DDDS.
Within each of these delegated name partitions, the string may be
assigned per local requirements.
e.g., urn:<assigned number>:thinkingcat.com:001203
Process for identifier resolution:
Domain name holders are responsible for operating or delegating
resolution servers for the FQDN in which they have assigned URNs.
Rules for Lexical Equivalence:
FQDNs are case-insensitive. Thus, the portion of the URN
urn:<assigned number>:<FQDN>:
is case-insensitive for matches. The remainder of the identifier
must be considered case-sensitive.
Conformance with URN Syntax:
No special considerations.
Validation mechanism:
None specified.
Scope:
Global.
B.2 Registration steps in practice
The key steps for registration of informal or formal namespaces
typically play out as follows:
Informal NID:
1. Complete the registration template. This may be done as part
of an Internet-Draft.
Daigle, et. al. Best Current Practice [Page 17]
RFC 3406 URN Namespace Definition Mechanisms October 2002
2. Communicate the registration template to urn-nid@apps.ietf.org
for technical review -- as a published I-D, or text e-mail
message containing the template.
3. Update the registration template as necessary from comments,
and repeat steps 2 and 3 as necessary.
4. Once comments have been addressed (and the review period has
expired), send a request to IANA with the revised registration
template.
Formal NID:
1. Write an Internet-Draft describing the namespace and include
the registration template, duly completed. Be sure to include
"Namespace Considerations", "Community Considerations" and
"IANA Considerations" sections, as described in Section 4.3.
2. Send the Internet-Draft to the I-D editor, and send a copy to
urn-nid@apps.ietf.org for technical review.
3. Update the Internet-Draft as necessary from comments, and
repeat steps 2 and 3 as needed.
4. Send a request to the IESG to publish the I-D as an RFC. The
IESG may request further changes (published as I-D revisions)
and/or direct discussion to designated working groups, area
experts, etc.
5. If the IESG approves the document for publication as an RFC,
send a request to IANA to register the requested NID.
Appendix C -- Changes from RFC 2611
This revision of [RFC2611] adds more detail describing the process of
registering a URN namespace identifier (in terms of mechanical
steps).
This version of the document also separates the process (mechanics)
from the discussion of the requirements for namespaces, attempting to
make the latter as objective as possible.
Throughout the document, references have been updated to the current
versions of the DDDS and related documentation (which collectively
obsolete [RFC2168] and related drafts).
Daigle, et. al. Best Current Practice [Page 18]
RFC 3406 URN Namespace Definition Mechanisms October 2002
C.1 Detailed Document Changes
Added table of contents
Section 2
Clarified the definition of a URN namespace, the uniqueness of
assignment, and that a single resource may have more than one
identifier associated with it.
Clarified the "number example" -- that the same string may appear in
2 different namespaces, and be applied to different resources.
Originally used ISBN/ISSN example, but structurally this is not
possible.
Section 3 (new)
This section explicitly defines the 3 categories of namespace --
Experimental, Informal and Formal. This section provides a
description of the intended use of the different namespace types, as
well as some acceptability guidelines for Formal namespaces (which
require IETF review).
Section 4.0
Spelled out the name of RFC 2434 ("IANA Considerations").
Provided a pointer to the IANA URN namespace registry.
Sections 4.1-4.3
New subsection divisions of the existing discussion of individual
namespace types.
Section 4.2
Corrected reference to URN Syntax document (RFC 2141, not RFC 2168).
Section 4.3
Added clarifying text as to the intended nature of Formal namespaces
and processes for registering them.
Added text to describe the requirement for a "Namespace
Considerations" section in RFCs defining Formal namespaces. Defined
the required content of that section.
Daigle, et. al. Best Current Practice [Page 19]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Added text to describe the new requirement for a "Community
Considerations" section in RFCs defining Formal namespaces. Defined
the required content of that section.
Added text to explicitly call out the need for an "IANA
Considerations" section in such RFCs, in order to alert IANA to
required action.
Added text to further clarify the (IETF) process for revising Formal
namespace registrations through the RFC and IETF review process.
Section 6
New section -- added text to describe the IANA considerations for
this document.
Section 7 -- References
Added references to revised NAPTR documentation ([RFC3401]), and the
previous version of this document ([RFC2611]).
Appendix A
Section created by moving the "URN Namespace Definition Template"
(RFC2611's Section 3) to an appendix.
Added references to the new requirements for "Namespace
Considerations", "Community Considerations", and "IANA
Considerations" sections for Formal namespace registrations.
Clarified the "Declared registrant of the namespace" template
element.
Added text to describe the purpose and scope of the "Validating
Mechanism".
Appendix B
Section B.1 is the "example template" that was "Section 5" in RFC
2611.
Update the sample "declared registrant" data per the changes to the
template description.
Removed the reference to "US-ASCII" in the "namespace specific
string" of the example namespace.
Daigle, et. al. Best Current Practice [Page 20]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Section B.2 (new)
This added section is a step-by-step walkthrough of the process for
registering Informal namespaces and Formal namespaces.
Authors' Addresses
Leslie L. Daigle
Thinking Cat Enterprises
EMail: leslie@thinkingcat.com
Dirk-Willem van Gulik
WebWeaving Internet Engineering
Nieuwsteeg 37A
2311 RZ Leiden
The Netherlands
URL: http://www.webweaving.org/
Email: dirkx@webweaving.org
Renato Iannella
IPR Systems Pty Ltd.
EMail: renato@iprsystems.com
Patrik Faltstrom
Cisco Systems Inc
170 W Tasman Drive SJ-13/2
San Jose CA 95134
USA
EMail: paf@cisco.com
Daigle, et. al. Best Current Practice [Page 21]
RFC 3406 URN Namespace Definition Mechanisms October 2002
Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Daigle, et. al. Best Current Practice [Page 22]