Network Working Group D. Tessman
Request for Comments: 4198 Zelestra
Category: Informational November 2005
A Uniform Resource Name (URN) Namespace for Federated Content
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright (C) The Internet Society (2005).
This document describes a URN (Uniform Resource Name) namespace for
identifying content resources within federated content collections.
A federated content collection often does not have a strong
centralized authority but relies upon shared naming, metadata, and
access conventions to provide interoperability among its members.
Federated content collections are often loose constructs of both
small and large content providers, with an active community, but
without significant central authority. Members are bound together by
shared purpose and interoperate through shared naming, metadata, and
access conventions. Federations may also consist of other
federations, creating complex associations and dependencies.
A content provider may join or leave a federation at any time and may
be part of more than one federation at the same time. Content
providers may also cease as organizations altogether, freeing their
domain names for use by others. In addition, content identifiers are
spread throughout the members of a federation. These identifiers are
stored on various media, sometimes for long durations before being
used. Therefore, although they work well in situations without a
strong content naming authority, URLs are insufficient as content
identifiers within a federation because they cannot be uniquely and
permanently tied to a specific content resource.
Tessman Informational [Page 1]RFC 4198 URN Namespace for Federated Content November 2005
This URN namespace provides a mechanism whereby a central naming
authority is not required. Providers maintain naming authority over
their own content within guidelines that guarantee URNs to be unique
A simple identifier resolution convention is also recommended to
provide a consistent URN resolver interface across all providers.
This namespace specification is for a formal namespace.
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 .
3. Specification Template
Registration Version Number: 1
Registration Date: 2005-04-25
Declared registrant of the namespace:
Address: 2314 Henrietta Avenue
La Crescenta, CA 91214-3007
Contact: Dave Tessman
Declaration of syntactic structure:
The NSS has the following ABNF  specification:
NSS = ProviderId ":" DateId ":" ResourceId
ProviderId = 1*(label ".") toplabel
DateId = (CCYY [MM [DD]]) / 1*3(DIGIT)
ResourceId = 1*(alphanum / other / ("%" hex hex))
label = alphanum / alphanum *(alphanum / "-") alphanum
toplabel = ALPHA / ALPHA *(alphanum / "-") alphanum
CCYY = 4(DIGIT)
Tessman Informational [Page 2]RFC 4198 URN Namespace for Federated Content November 2005
MM = ("0" %x31-39) / ("1" %x30-32)
DD = ("0" %x31-39) / (%x31-32 DIGIT) / "30" / "31"
alphanum = ALPHA / DIGIT
hex = DIGIT / %x41-46 / %x61-66
other = "(" / ")" / "+" / "," / "-" / "." / ":" / "=" /
"@" / ";" / "$" / "_" / "!" / "*" / "'"
ProviderId is the content provider's identifier. ProviderId MUST
be an Internet domain name and MUST be owned by the organization
creating the resource and allocating the URN to the resource.