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].
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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:
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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.
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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.
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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.
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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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