URN Namespace for CCSDS: A Uniform Resource Name (URN) Namespace for the Consultative Committee for Space Data Systems (CCSDS)
Permanent names for space data system standards and documents.
Blanchet, M., Schiltknecht, A., and P. Shames, "A Uniform Resource Name (URN) Namespace for the Consultative Committee for Space Data Systems (CCSDS)", RFC 7738, DOI 10.17487/RFC7738, January 2016, <https://www.rfc-editor.org/info/rfc7738>.
@misc{rfc7738,
series = {Request for Comments},
number = 7738,
howpublished = {RFC 7738},
publisher = {RFC Editor},
doi = {10.17487/RFC7738},
url = {https://www.rfc-editor.org/info/rfc7738},
author = {M. Blanchet and A. Schiltknecht and P. Shames},
title = {{A Uniform Resource Name (URN) Namespace for the Consultative Committee for Space Data Systems (CCSDS)}},
pagetotal = 8,
year = 2016,
month = jan,
} RFC text
Contents
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
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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
AI ELI5
On this page
§1CCSDS and Persistent Naming
The Consultative Committee for Space Data Systems (CCSDS) is an international organization formed in 1982 by major space agencies to develop standards for space data systems. It currently includes eleven member agencies (like NASA, ESA, JAXA), twenty-eight observer agencies, and over 100 industrial partners. CCSDS publishes protocol recommendations and XML schemas defining how space systems communicate.
CCSDS documents and the XML schemas they define need persistent, globally unique names that survive document moves, repository changes, and organizational restructuring. A Uniform Resource Name (URN) provides such a name: it identifies a resource by what it is, not where it is located. RFC 7738 registers a formal URN namespace identifier (NID) called "ccsds", enabling CCSDS to assign permanent names to its standards and schemas through the Space Assigned Numbers Authority (SANA), its designate naming authority.
A big space organization writes standards. They need permanent names for documents so people can refer to them in contracts and other documents without the reference breaking when a website moves.
§2URN Syntax and Namespace Structure
A Uniform Resource Name follows the syntax urn:nid:nss, where nid is the namespace ID and nss is the namespace-specific string. For CCSDS, names follow the pattern urn:ccsds:subnamespace:identifier. The second component, subnamespace, is called the Subnamespace IDentifier (SNID) and distinguishes categories like "document", "schema", or "registry". The third component is a unique identifier within that subnamespace.
An example name is urn:ccsds:document:313x0y1 (a document) or urn:ccsds:schema:ndm:aem (an XML schema). SANA assigns SNIDs, and each SNID has its own assignment process defined by a CCSDS document. The only restriction RFC 7738 enforces is that the SNID part is case-insensitive for comparison purposes; the system must normalize case before checking if two names refer to the same resource.
Names have three parts: the URN label, a category (like document or schema), and a unique number within that category. SANA hands out new categories and numbers.
§3IANA Registration and Governance
RFC 7738 formally registers "ccsds" as a URN namespace identifier with IANA following RFC 3406 (URN Namespace Definition Mechanisms). The registration occurred on 2015-10-19. The registering organization is the CCSDS Secretariat at NASA's Office of Space Communication. The designated contact is SANA (Space Assigned Numbers Authority), which maintains a public registry of all CCSDS subnamespace identifiers and their assignment procedures at sanaregistry.org.
CCSDS commits to maintaining identifier persistence: resources assigned URNs will remain accessible and retain their names indefinitely. Unique identifier assignment is limited to CCSDS and authorities explicitly designated by CCSDS, following rules specified in this document or in future CCSDS recommendations. The registration also notes that while CCSDS space data systems are openly available, no immediate resolution method exists yet (a Resolution Discovery System), but the namespace design does not preclude future resolution infrastructure.
The system is officially registered with the Internet authority (IANA). NASA manages it. SANA keeps the list of who gets to hand out new names.
§4Scope and Community Use
The CCSDS URN namespace covers global scope: URNs are relevant for space agencies' networks both in space and on Earth. Usage includes CCSDS protocol documents, XML schemas, and CCSDS registries. Organizations cite CCSDS standards in specifications, contracts, and implementations. Some space missions are required by their funding agencies to use CCSDS standards, so a permanent, widely-recognized way to refer to those standards avoids ambiguity.
CCSDS maintains public registries of standards and schemas, ensuring organizations can discover which URNs are valid. The decentralized assignment through SANA allows different CCSDS working groups to manage their own subnamespaces while maintaining global uniqueness through the central authority. This supports the vision of space agencies across the world citing and implementing the same standards without depending on any single repository or organization's infrastructure.
Astronauts and ground stations all over the world can use the same names for standards. Even if one country's website goes down, the names are still valid everywhere else.
§5Validation and Lexical Rules
Validation of URNs in the CCSDS hierarchy depends on the specific SNID. When a new subnamespace is assigned, the defining CCSDS document specifies how to validate identifiers in that subnamespace. URNs without an assigned SNID are invalid. Reserved characters (%, /, ?, #) should generally be forbidden in the namespace-specific string portion to maintain compatibility with URI standards, but this is a recommendation rather than a requirement.
For lexical equivalence (determining if two URNs refer to the same resource), the SNID part is case-insensitive; systems must normalize case before comparing. The rest of the URI follows general URN character rules as defined in RFC 2141.
New categories of things (schemas, documents, etc.) can define their own naming rules. The system is case-insensitive when comparing names, so "DOCUMENT" and "document" mean the same thing.