Network Working Group                                            C. Reed
Request for Comments: 5165                    Open Geospatial Consortium
Category: Informational                                       April 2008


            A Uniform Resource Name (URN) Namespace for the
                    Open Geospatial Consortium (OGC)

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.

Abstract

   This document describes a Uniform Resource Name (URN) namespace that
   is engineered by the Open Geospatial Consortium (OGC) for naming
   persistent resources published by the OGC.  The formal Namespace
   IDentifier (NID) is "ogc".

1.  Introduction

   The Open Geospatial Consortium (OGC) is a voluntary consensus
   standards organization.  Founded in 1994, the OGC produces many kinds
   of technical documents, including: standards, working drafts,
   technical reports, discussion papers, and XML schemas.  The OGC
   wishes to provide persistent, location-independent Identifiers for
   these resources.  Further, a number of OGC standards and application
   schemas of OGC standards are now used and/or referenced by standards
   specifications from other standards organizations, including OASIS,
   the IETF, IEEE, ISO, and OMA.

   The OGC core mission is to develop spatial interface and encoding
   specifications that are openly available and royalty free.  Products
   and services that conform to OGC interface specifications enable
   users to freely exchange and process spatial information across
   networks, computing platforms, and products.  Interoperability in
   such an environment is facilitated by the use of a system of
   persistent identifiers that are global in scope.  The OGC is the only
   standards organization whose mission is specifically focused in
   interfaces and encodings for geospatial content and services.

   Motivated by these concerns, the OGC would like to assign formal URNs
   to published resources in order to provide persistent, location-
   independent identifiers for them.  The process for registering a
   namespace identifier is documented in RFC 3406 [2].

   The official IANA registry of URN namespaces is available online:
   <http://www.iana.org/assignments/urn-namespaces>.

   2.  URN Specification for "ogc" NID

   Namespace ID:

      ogc

   Registration Information:

      Registration Version Number: 1
      Registration Date: 2007-08-16

   Declared registrant of the namespace:

      Open Geospatial Consortium, Inc. (Headquarters)
      35 Main Street, Suite 5
      Wayland, MA 01778-5037, USA
      c/o Carl Reed (creed@opengeospatial.org)

   Declaration of syntactic structure:

      The Namespace Specific String (NSS) of all URNs that use the "ogc"
      NID will have the following structure:

         urn:ogc:{OGCresource}:{ResourceSpecificString}

      where the "OGCresource" is a US-ASCII string that conforms to the
      URN syntax requirements [1] and defines a specific class of
      resource type.  Each resource type has a specific labeling scheme
      that is covered by "ResourceSpecificString", which also conforms
      to the naming requirements of [1].  The only exception is that the
      character ":" shall not be used as part of the "OGCresource"
      string.  This is to avoid possible confusion.  Further,
      "OGCresource" is case sensitive.

      The OGC maintains a naming authority, the OGC Naming Authority
      (ONA), that will manage the assignment of  "OGCresources" and the
      specific registration values assigned for each resource class.

   Relevant ancillary documentation:

      The OGC Naming Authority (ONA) provides information on the
      registered resources and the registrations for each.  More
      information about ONA, the registration activities, and procedures
      to be followed are available at:

      https://portal.opengeospatial.org/wiki/twiki/bin/view/
      Member/OGCUrnIntro

      An operational OGC URN "resolver" is available at
      http://urn.opengis.net/.  The resolver provides a registry of the
      currently member approved OGC URN's used in currently approved and
      implemented OGC standards.

      The OGC Naming Authority is a permanent OGC resource.  The
      documents and related OGC URN resources, such as the URN resolver,
      have stable URLs.  The ONA reference is
      http://www.opengeospatial.org/ogcna.

      There are a number of OGC Best Practice and Standards documents
      that define member agreements on the definitions for "OGCresource"
      and ResourceSpecificString.

   Identifier uniqueness considerations:

      The ONA manages resources using the "ogc" NID and will be the
      authority for managing the resources and subsequent strings
      associated.  In the associated procedures, ONA will ensure the
      uniqueness of the strings themselves or shall permit secondary
      responsibility for the management of well-defined sub-trees.

      The OGC may permit the use of experimental type values that will
      not be registered.  As a consequence, multiple users may end up
      using the same value for separate uses.  As experimental usage is
      only intended for testing purposes, this should not be a real
      issue.

   Identifier persistence considerations:

      The OGC provides clear documentation on a number of the registered
      uses of the "ogc" NID.  Additional uses developed by the OGC
      membership in the future will be first approved by the ONA and
      then by the entire OGC voting membership.  This is the normal
      process for all OGC documents that become OGC standards or other
      permanent resources for use by the community.

      The OGC Naming Authority maintains a permanent registry of
      approved uses.  This resource is structured such that each
      "OGCresource" has a separate description and registration table.

      The registration tables and information are published and
      maintained by the ONA on the OGC web site.

   Process of identifier assignment:

      The ONA uses the approved OGC standards policies and procedures
      for discussion, approval, and registration of each type of
      resource maintained [3].

      Each such resource may have three types of registration
      activities:

         1) Registered values associated with OGC specs or services
         2) Registration of values or sub-trees to other entities
         3) Name models for use in experimental purposes

   Process for identifier resolution:

      The namespace is not listed with a Resolution Discovery System
      (RDS); this is not relevant.

   Rules for Lexical Equivalence:

      No special considerations except as noted in the declaration of
      syntactic structure; the rules for lexical equivalence of [1]
      apply.

   Conformance with URN Syntax:

      No special considerations.

   Validation mechanism:

      None specified.  URN assignment will be handled by procedures
      implemented in support of ONA activities.

   Scope:

      Global

3.  Examples

   The following examples are representative URNs that have been
   assigned by the ONA.

      urn:ogc:specification:gml:doc-is(02-023r4):3.0.0

   Defines the URN to be used to identify version 3.0.0 of an OGC
   specification document for the Geography Markup Language in the OGC
   document archives.

      urn:ogc:serviceType:CatalogueService:2.0.2:HTTP

   Defines the URN to be used for an application to specify the specific
   service type for an OGC Catalogue service.

      urn:ogc:def:crs:EPSG:6.3:26986

   This is the URN literal to reference the definition of the Coordinate
   Reference System (CRS) with code 26986 that is specified in version
   6.3 of the EPSG database [4].

4.  Namespace Considerations

   There is currently no available namespace that will allow the OGC to
   uniquely specify and access resources, such as schemas and
   registries, that are required by organizations implementing OGC
   standards.  There is also a need for other standards organizations,
   such as OASIS and the IETF, to be able to access OGC specific
   resources.

   The geospatial and location services industry will benefit from the
   publication of this namespace by having more permanent and reliable
   names for the XML namespaces, schema locations, standards document
   reference, and other document artifacts required for implementation
   of an OGC standard.

   The OGC members considered the use of other existing NIDs, such as
   those for OASIS and OMA.  However, the semantics for geospatial
   content and services have a number of unique characteristics, such as
   the expression of coordinate reference systems.  The URN syntax used
   by OASIS and OMA do not support the necessary elements to express the
   full semantics used in and by the geospatial community.

5.  Community Considerations

   Both the traditional geospatial and location services industry as
   well as the broader IT community will benefit from the publication of
   this namespace by providing permanent and reliable names for the XML
   namespaces, schema locations, catalogues registries, and other
   document artifacts required for implementation of an OGC standard.

   We desire these resources to be freely and openly available as a set
   of community resources.  Not only can OGC members identify and submit
   new proposals for additional resources, but any individual or
   organization can make a contribution by submitting a proposal to the
   OGC for consideration by the ONA.  Normal OGC standards discussion
   and approval processes will be used to process any new community
   contribution.

   Since 2003, the OGC membership has been developing expertise in using
   the OGC URN.  The knowledge and experience gained through
   implementation experiments and a variety of operational test beds
   contributed to the current OGC URN specification.  The knowledge is
   documented in OGC documents (above) as well as an operational OGC URN
   resolver.  Work is also underway on a publicly accessible OGC URN
   registry.  These resources are necessary for a number of reasons,
   including the fact that numerous agencies and organizations, such as
   NATO and NGA, have mandated a procurement policy that requires OGC
   standards and their related OGC URNs.

6.  Security Considerations

   There are no additional security considerations other than those
   normally associated with the use and resolution of URNs in general.

7.  IANA Considerations

   This document defines a URN NID registration of "ogc", which has been
   entered into the IANA registry located at
   <http://www.iana.org/assignments/urn-namespaces>.

8.  Normative References

   [1] Moats, R., "URN Syntax", RFC 2141, May 1997.

   [2] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
       "Uniform Resource Names (URN) Namespace Definition Mechanisms",
       BCP 66, RFC 3406, October 2002.

   [3] OGC Technical Committee Policies and Procedures, Version 3,
       October 1, 2007. Available (online):
       https://portal.opengeospatial.org/files/?artifact_id=12586

   [4] "Definition identifier URNs in OGC namespace" Version 1.1 Arliss
       Whiteside, An OGC Best Practices, August 2006. Available
       (online):
       http://portal.opengeospatial.org/files/?artifact_id=16339

Author Address

   Carl Reed, PhD
   Chief Technology Officer
   Open Geospatial Consortium, Inc.
   35 Main Street, Suite 5
   Wayland, MA 01778-5037, USA

   EMail:   creed@opengeospatial.org

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