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 Notice
Copyright (C) The Internet Society (2005).
Abstract
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.
1. Introduction
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 and permanent. 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. 2. Terminology 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 [1]. 3. Specification Template Namespace ID: "fdc" Registration Information: Registration Version Number: 1 Registration Date: 2005-04-25 Declared registrant of the namespace: Name: Zelestra Address: 2314 Henrietta Avenue La Crescenta, CA 91214-3007 USA Contact: Dave Tessman E-mail: dtessman@zelestra.com Declaration of syntactic structure: The NSS has the following ABNF [2] 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. DateId is a date in ISO 8601 Basic Format (CCYY[MM[DD]]), and MUST correspond to a specific day on which the organization allocating the URN owned the domain name specified in the ProviderId. If not included, the default value for MM and DD is "01". DateIds of 1 to 3 digits are reserved. ResourceId MUST be unique among all ResourceIds emanating from the same provider and having the same DateId. Relevant ancillary documentation: None. Identifier uniqueness considerations: The combination of ProviderId and DateId serves to uniquely identify the organization that is allocating the URN. That organization is responsible for ensuring the uniqueness of the ResourceId. Identifier persistence considerations: A URN of this namespace may only be allocated by an organization that owns an Internet domain name. The URN identifies a date on which the organization owned that domain name. The combination of domain name and date will serve to uniquely identify that organization for all time. Process of identifier assignment: The organization identified by the ProviderId/DateId combination is responsible for allocating a ResourceId that is unique among all those that it allocates with that DateId. Tessman Informational [Page 3]
RFC 4198 URN Namespace for Federated Content November 2005 Process of identifier resolution: Content providers are responsible for the provision of a URN resolution service, if any, for URNs they have assigned with a valid ProviderId/DateId combination. Content providers SHOULD support URN resolution by using the HTTP protocol convention described in RFC 2169 [3]. The ProviderId SHOULD be used as the HTTP server location. Rules for Lexical Equivalence: In addition to the rules defined in RFC 2141 [4], normalize the case of the ProviderId to lower case before comparison. Conformance with URN Syntax: There are no additional characters reserved. Validation mechanism: None additional to resolution specified. Scope: Global 4. Examples The following examples are representative of URNs in this namespace, but may not refer to actual resources. urn:fdc:example.com:2002:A572007 urn:fdc:example.net:200406:ivr:51089 urn:fdc:example.org:20010527:img089322-038 5. Security Considerations There are no additional security considerations other than those normally associated with the use and resolution of URNs in general. 6. Namespace Considerations Distribution of naming authority, identifier flexibility, and a recommended URN resolution mechanism make this namespace a unique and valuable tool to meet the URN requirements of small content providers and federated content collections. Tessman Informational [Page 4]
RFC 4198 URN Namespace for Federated Content November 2005 7. Community Considerations By establishing a simple, flexible, and efficient means for smaller content providers to uniquely identify and publish their content, this namespace reduces the effort required for these providers to participate in federated collections. A consistent identifier format and resolution mechanism also increases the ability of federations to accept content references from smaller providers and to aggregate themselves into federations of federations. Increased participation and aggregation results in a larger selection of distinctive content that is more accessible to the community. To make use of this namespace, a content provider should further decompose the ResourceId portion of the namespace syntactic structure to meet their internal content identification needs and establish an internal governance mechanism to ensure that all identifiers created follow the requirements of this namespace. It is also recommended that the identifier resolution mechanism described in RFC 2169 [3] be provisioned within an HTTP server designated by the ProviderId portion of the namespace syntactic structure. 8. IANA Considerations This document includes a URN NID registration that conforms to RFC 3406 [5] and has been entered into the IANA registry of URN NIDs. 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", RFC 4234, October 2005. [3] Daniel, R., "A Trivial Convention for using HTTP in URN Resolution", RFC 2169, June 1997. [4] Moats, R., "URN Syntax", RFC 2141, May 1997. Informative References [5] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, "Uniform Resource Names (URN) Namespace Definition Mechanisms", BCP 66, RFC 3406, October 2002. Tessman Informational [Page 5]
RFC 4198 URN Namespace for Federated Content November 2005 Author's Address Dave Tessman Zelestra 2314 Henrietta Avenue La Crescenta, California 91214-3007 USA Phone: +1 818 249 8906 EMail: dtessman@zelestra.com Tessman Informational [Page 6]
RFC 4198 URN Namespace for Federated Content November 2005 Full Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Tessman Informational [Page 7]
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