A Uniform Resource Name (URN) Namespace for the Open Geospatial Consortium (OGC)
draft-creed-ogc-urn-03

Network Working Group                                            C. Reed
Internet-Draft                                Open Geospatial Consortium
Expires: April 15, 2008                                 October 16, 2007
                                                                       
            A Uniform Resource Name (URN) namespace for the 
                    Open Geospatial Consortium (OGC)
                      draft-creed-ogc-urn-03.txt 

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   Copyright (C) The IETF Trust (2007).

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 
   
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   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:

      The NID "ogc" is requested.

   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 [RFC2141] 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 [RFC2141]. 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.

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      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 and 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,
      will have stable URLs.
      
      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 management of well-defined sub-trees.

      OGC may permit 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
      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 ONA on the OGC web site.
 
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    Process of identifier assignment:

      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
      [RFC 2141] 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

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      Is the URN defined 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 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 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 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. So can 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 
      organization, such as NATO and NGA, have mandated procurement
      policy that requiring OGC standards and their related OGC URNs.

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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. Available [online]:
     <http://www.ietf.org/rfc/rfc2141.txt>
      
     [2] Daigle, L. et al., "Uniform Resource Names (URN) Namespace 
     Definition Mechanisms", RFC 3406, October 2002. Available [online]: 
     http://www.ietf.org/rfc/rfc3406.txt

     [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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Acknowledgement(s)
   Thanks to Jon Peterson, Leslie Daigle, Allison Mankin, Simon Cox,
   Clemens Portele, Doug Nebert, Steven Keens, Josh Lieberman and 
   Arliss Whiteside for their review and comments. Thanks to Ted Hardie
   Brian Rosen, Allison Mankin, and Lisa Dusseault for helping me 
   with the IETF document process. Thanks to Peter Saint-Andre,
   Stefan Santesson, Alfred Hines, and Joel Halpern for their 
   reviews of the document.