Internet Engineering Task Force (IETF)                       M. Blanchet
Request for Comments: 7738                               A. Schiltknecht
Category: Informational                                    Viagenie/SANA
ISSN: 2070-1721                                                P. Shames
                                         Jet Propulsion Laboratory, NASA
                                                            January 2016


              A Uniform Resource Name (URN) Namespace for
       the Consultative Committee for Space Data Systems (CCSDS)

Abstract

   This document describes a Uniform Resource Name (URN) namespace
   intended for persistently and uniquely naming resources published by
   the Consultative Committee for Space Data Systems (CCSDS).

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7738.

Copyright Notice

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language Section . . . . . . . . . . . . . . . .   3
   3.  URN Specification for "ccsds" Namespace ID  . . . . . . . . .   3
     3.1.  Namespace ID  . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Registration Information  . . . . . . . . . . . . . . . .   3
     3.3.  Declared Registrant of the Namespace  . . . . . . . . . .   3
     3.4.  Declaration of Syntactic Structure  . . . . . . . . . . .   4
     3.5.  Relevant Ancillary Documentation  . . . . . . . . . . . .   4
     3.6.  Identifier Uniqueness Considerations  . . . . . . . . . .   4
     3.7.  Identifier Persistence Considerations . . . . . . . . . .   4
     3.8.  Process of Identifier Assignment  . . . . . . . . . . . .   5
     3.9.  Process for Identifier Resolution . . . . . . . . . . . .   5
     3.10. Rules for Lexical Equivalence . . . . . . . . . . . . . .   5
     3.11. Conformance with URN Syntax . . . . . . . . . . . . . . .   5
     3.12. Validation Mechanism  . . . . . . . . . . . . . . . . . .   5
     3.13. Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Namespace Considerations  . . . . . . . . . . . . . . . . . .   6
   6.  Community Considerations  . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Consultative Committee for Space Data Systems (CCSDS) [CCSDS] was
   formed in 1982 by the major space agencies of the world to provide a
   forum for discussion of common problems in the development and
   operation of space data systems.  At the time of publication of this
   document, it is composed of eleven member agencies, twenty-eight
   observer agencies, and over 100 industrial associates.  Since its
   establishment, CCSDS has been actively developing recommendations for
   data- and information-systems standards, intended to promote
   interoperability and cross support among cooperating space agencies.

   CCSDS has a permanent secretariat reporting to the CCSDS Engineering
   Steering Group, which maintains documents for the CCSDS protocols.
   CCSDS also has its Naming Authority under the Space Assigned Number
   Authority (SANA) [SANA] that manages its registries and namespaces.

   CCSDS produces protocol standards documents requiring a permanent and
   unique namespace.  CCSDS also uses Extensible Markup Language (XML)
   schemas to define XML messaging in its various protocols
   recommendations.  These schemas require a persistent, unique, and
   location-independent namespace for identification purposes.

   This namespace specification is for a formal namespace identifier
   (NID), as per [RFC3406].

2.  Requirements Language Section

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  URN Specification for "ccsds" Namespace ID

3.1.  Namespace ID

      "ccsds"

3.2.  Registration Information

      Registration version number: 1

      Registration date: 2015-10-19

3.3.  Declared Registrant of the Namespace

   Registering organization:

      Consultative Committee for Space Data Systems (CCSDS) Secretariat

      Office of Space Communication (Code M-3)

      National Aeronautics and Space Administration

      Washington, DC 20546, USA

      Email: secretariat@mailman.ccsds.org

   Designated Contact:

      Space Assigned Numbers Authority (SANA)

      Email: info@sanaregistry.org

      http://sanaregistry.org

3.4.  Declaration of Syntactic Structure

   The formal syntax definitions below are given in ABNF [RFC5234].

   The namespace-specific string (NSS) in the urn:ccsds names hierarchy
   begins with a subnamespace identifier (SNID), followed by a delimiter
   and a subnamespace-dependent string

   CCCSDS-URN = "urn:ccsds:" SNID ":" SUBNAMESPACE-SPECIFIC-STRING

   where <SNID> is a unique subnamespace identifier for the
   specification, and <SUBNAMESPACE-SPECIFIC-STRING> is a unique
   identifier within the subnamespace identifier scope.

   <SNID> has the same syntax as an <NID> as defined in [RFC2141].

   SANA assigns SNIDs.

   The syntax of <SUBNAMESPACE-SPECIFIC-STRING> is dependent on the
   <SNID> and MUST be defined by a CCSDS document.  This document does
   not pose any additional restrictions to the <SUBNAMESPACE-SPECIFIC-
   STRING> other than what is defined in the NSS syntax as defined by
   [RFC2141]:

   SUBNAMESPACE-SPECIFIC-STRING = 1*<URN chars>

   <URN chars> is defined in Section 2.2 of [RFC2141].

3.5.  Relevant Ancillary Documentation

   SANA keeps the "urn:ccsds" namespace as a registry [SANA-Reg].
   Procedures to register a subnamespace identifier are described in the
   header of the registry.

3.6.  Identifier Uniqueness Considerations

   SANA is the authority responsible for uniqueness of identifiers by
   the recommendations of CCSDS.  SANA will assign unique identifiers
   and keep a public registry [SANA-Reg].

3.7.  Identifier Persistence Considerations

   CCSDS is committed to guaranteeing the accessibility and persistence
   of all the resources that are assigned URNs.

3.8.  Process of Identifier Assignment

   Assignment of identifiers is limited to CCSDS and those authorities
   explicitly designated by CCSDS.  CCSDS is committed to assigning URN
   identifiers only in accordance with the rules specified in this
   document or in future updates to this document, either published as
   IETF RFC documents or as CCSDS recommendations.

3.9.  Process for Identifier Resolution

   The CCSDS namespace is not currently listed with a Resolution
   Discovery System (RDS), but nothing about the namespace prohibits the
   future definition of appropriate resolution methods or listing with
   an RDS.

3.10.  Rules for Lexical Equivalence

   The <SNID> part of URNs in the CCSDS hierarchy is case insensitive.
   Thus, the <SNID> MUST be case normalized before comparison.

3.11.  Conformance with URN Syntax

   The intention of this document is to only restrict the syntax of the
   <SNID>.  The syntax of the <SUBNAMESPACE-SPECIFIC-STRING> follows the
   general syntax of a URN:

   SUBNAMESPACE-SPECIFIC-STRING = 1*<URN chars>

   Documents defining a subnamespace identifier SHOULD specify further
   syntactic restrictions in <SUBNAMESPACE-SPECIFIC-STRING>.  It is
   RECOMMENDED that these documents forbid the assignment of URNs
   containing characters in the <reserved> set ("%", "/", "?", and "#")
   as defined in [RFC2141].  This is in accordance with Section 2.2 of
   [RFC3986].

3.12.  Validation Mechanism

   The validation mechanism of URNs in the hierarchy is specific for
   each SNID and SHOULD be defined when an SNID is assigned.

   URNs in the hierarchy without an assigned SNID are considered to be
   invalid.

3.13.  Scope

   Global URNs are relevant for the space agencies networks both in
   space and on Earth.

4.  Examples

   URNs in this section are not guaranteed to be real and are listed
   here only for illustration purposes.  The following are examples of
   valid URNs for the "document" and "schema" categories:

      urn:ccsds:document:313x0y1

      urn:ccsds:schema:ndm:aem

5.  Namespace Considerations

   CCSDS is an international standards development organization in the
   field of space and Earth communications.  The use of this URN
   hierarchy is expected to be broad, including but not limited to usage
   for:

      CCSDS documents

      XML Schemas

      CCSDS registries

   The CCSDS documents and registries are available openly.

6.  Community Considerations

   Usage of the URN namespace has been requested within the CCSDS
   community for various projects.

7.  Security Considerations

   No additional security considerations are relevant, other than those
   normally related with the general use and resolution of URNs.

8.  IANA Considerations

   IANA has registered the "ccsds" NID within the IANA registry of URN
   NIDs in the "Formal URN Namespaces" subregistry.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141,
              May 1997, <http://www.rfc-editor.org/info/rfc2141>.

   [RFC3406]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "Uniform Resource Names (URN) Namespace Definition
              Mechanisms", BCP 66, RFC 3406, DOI 10.17487/RFC3406,
              October 2002, <http://www.rfc-editor.org/info/rfc3406>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <http://www.rfc-editor.org/info/rfc3986>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <http://www.rfc-editor.org/info/rfc5234>.

9.2.  Informative References

   [CCSDS]    CCSDS, "The Consultative Committee for Space Data
              Systems", <http://www.ccsds.org/>.

   [SANA]     SANA, "Space Assigned Numbers Authority",
              <http://sanaregistry.org/>.

   [SANA-Reg] SANA, "Space Assigned Number Authority (SANA) Registry",
              <http://sanaregistry.org/r/urn>.

Acknowledgements

   This document is based on previous draft versions authored by Martin
   A. Soto and Louis Reich.  This document was reviewed by the XML
   Steering Group (XSG) of the Systems Engineering and Architecture Area
   (SEA) in CCSDS.

Authors' Addresses

   Marc Blanchet
   Viagenie/SANA
   246 Aberdeen
   Quebec, QC  G1R 2E1
   Canada

   Email: Marc.Blanchet@viagenie.ca
   URI:   http://viagenie.ca


   Audric Schiltknecht
   Viagenie/SANA
   246 Aberdeen
   Quebec, QC  G1R 2E1
   Canada

   Email: audric.schiltknecht@viagenie.ca
   URI:   http://viagenie.ca


   Peter Shames
   Jet Propulsion Laboratory, NASA

   Email: peter.m.shames@jpl.nasa.gov
   URI:   http://cwe.ccsds.org/sea/default.aspx