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Network Working Group                                         D. TessmanRequest for Comments: 4198                                      ZelestraCategory: Informational                                    November 2005A Uniform Resource Name (URN) Namespace for Federated ContentStatus 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 inRFC 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 inRFC 2169 [3].  The ProviderId     SHOULD be used as the HTTP server location.   Rules for Lexical Equivalence:      In addition to the rules defined inRFC 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:      Global4.  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:img089322-0385.  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 20057.  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 inRFC 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 toRFC3406 [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 2005Author's Address   Dave Tessman   Zelestra   2314 Henrietta Avenue   La Crescenta, California 91214-3007   USA   Phone: +1 818 249 8906   EMail: dtessman@zelestra.comTessman                      Informational                      [Page 6]

RFC 4198          URN Namespace for Federated Content      November 2005Full Copyright Statement   Copyright (C) The Internet Society (2005).   This document is subject to the rights, licenses and restrictions   contained inBCP 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 inBCP 78 andBCP 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 athttp://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]