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The History of the gmi Namespace

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tedhabermann edited this page Dec 26, 2014 · 22 revisions

Introduction

The gmi namespace was created shortly after ISO 19115-2 (the conceptual model) was published in order to provide an XML implementation for the concepts included in ISO 19115-2. There are a number of schema implementations available for this namespace. These versions were created by users that needed them to use 19115-2. This page tries to recreate the history of the namespace as if we were using git to track versions.

The directory structure for the repository reflects the structure we are trying to encourage for the ISO TC211 Schema Repository: namespace/version/date (yyyy-mm-dd)/*.xsd

The date directories were created using the dates of the actual schema edits. The root directory is where changes are merged into the current best schema.

Document/Schema Timeline

Three critical documents were created as ISO 19115-2 neared final status:

  1. The Final Committee Draft (Doc. # 2171) - 2007-03-08

  2. The Draft International Standard (Doc. # 2287) - 2007-09-19

  • The Initial Schema - 2008-04-04
  1. The International Standard (Doc. # 2492) - 2008-07-21
  • The NGDC Schema - 2009-04-30

  1. 19139-2 The XML Implementation Project Team initial meeting - 2011-05-23

  2. ISO/TC211 Doc. #3305 - Final text for TS, ISO/DTS 19139-2 (2012-03-26)

  3. ISO/TC211 Doc. #3307 - Internal note related to document N 3305 (2012-03-26)

  1. 19139-2 (Doc. #3411) Final Technical Specification - 2012-10-24

Initial Schemas

The first schemas were created on April 4, 2008 at IGN, several months after the Draft International Standard was published. They include an initial comment that says "edited with XMLSpy v2005 rel. 3 U (http://www.altova.com) by STEPHANE BIDAULT (I.G.N/SAF/RECEPTIONS)" and documentation that says "This file was generated from ISO TC/211 UML class diagrams == 04-04-2008 17:12:48 ======".

The details of how these schema were created are not clear. As far as I know, no automated mechanism for schema generation existed during 2008. There are also several inconsistencies between Figures A.8 and A.9 in ISO/DIS 19115-2. In any case, there were a number of errors and omissions in the schemas. For example, the MI_EnvironmentalRecord class was omitted, MD_Identifiers were missing from several classes, and cardinalities were incorrect in many cases.

#The NGDC Schemas (2009-05-01) The metadata group at NOAA's National Geophysical Data Center (NGDC) was working to encourage the adoption of ISO 19115-2 in NOAA. A schema that matched the International Standard was critical in this adoption process. Ted Habermann and Anna Milan, in consultation with Nicholas Lesage and others at IGN, made a series of edits that brought the schema closer to compliance with the published standard. Missing elements were added and cardinalities were corrected as noted in comments in these schema documents. The fact that the MI_EnvironmentalRecord class was missing was not noticed at NGDC, so it was not added to the schema.

These corrections were added to the git repository in the branch NGDC-Fixes-to-19115-2.

#ISO 19139-2 The XML Implementation Creation of the offical XML Implementation of 19115-2 (ISO 19139-2) started with a new work item proposal during 2010 and the final ISO Technical Specification was published during 2012. The final schemas were generated from ISO TC/211 UML class diagrams during July 2011. They include the statement "This file was generated from ISO TC/211 UML class diagrams == 07-30-2010 11:34:36 ======".

These schemas are available from in the ISO TC211 schema repository at http://www.isotc211.org/2005/gmi. This directory was created during July 2011, a year after the schemas were created. The files were uploaded during March of 2012, at the same time as the release of the final text for 19139-2 (Doc. #3305) and an internal note (Doc. #3307) describing XMG responsibilities with respect to those schemas.

According to the documentation in these schemas, they were generated from the ISO/TC/211 UML diagrams, but it is not clear exactly how this was done. Unfortunately, the order of the classes in this version of the schema is completely different from the order of the classes in the NGDC schema, making it difficult to identify specific differences. This order does not effect the performance of the schema, but it makes it difficult to understand the changes. In order to simplify this process, the order of the classes were changes in the Adjust-order branch of the 2010-07-30 directory in the repository.

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