View source for ISO/TS 19115-3 Geographic information - Metadata - Part 3: XML implementation of fundamentals

==Overview==
{| class="wikitable"
| Full name
| ISO/TS 19115-3, Geographic information – Metadata – Part 3: XML implementation of fundamentals
|-
| Version
| Draft Technical Specification (DTS)
|-
| Amendments
| None
|-
| Corrigenda
| None
|-
| Published by
| ISO/TC 211
|-
| Languages
| English
|-
| Online overview
| Not yet available
|-
| Type of standard
| ISO International Standard
Application level
|-
| Related standard(s)
| ISO 19118:2011, Geographic information – Encoding<br/>
ISO 19136:2007, Geographic information – Geography Markup Language (GML)<br/>
ISO/TS 19139:2007, Geographic information – Metadata – XML schema implementation
|-
| Application
| XML implementation of ISO 19115-1, ''Geographic information – Metadata – Part 1: Fundamentals''
|-
| Conformance classes
| As this standard is an XML implementation, it specifies many conformance classes for the XML schema implementation that can be tested automatically by a validation tool that implements the full W3C XML Schema.
|}

== Scope ==
ISO/TS 19115-3 defines five artefacts to support the use of ISO 19115-1 compliant metadata and migration from ISO19115 to ISO19115-1. These include 

1) an XML Schema that implements ISO 19115-1 using encoding rules from ISO 19118 Annex A and ISO 19139 for XML metadata encoding; 

2) a set of ISO/IEC 19757-3 (Schematron) rules that implement validation constraints included in the ISO 19115-1 UML Model that are not specified by the XML schema; 

2a) a set of ISO/IEC 19757-3 (Schematron) rules that identify content in documents encoded using the XML schema defined in ISO 19115-1 (this Technical Specification) that will not translate to ISO 19115 metadata encoded using the ISO 19139 XML schema; 

3) an Extensible Stylesheet Language Transformation (XSLT) for transforming XML-encoded ISO 19115 metadata using the ISO 19139 XML schema into an equivalent document encoded using the XML schema defined in ISO 19115-3 (this Technical Specification); and 

3a) an Extensible Stylesheet Language Transformation (XSLT) for transforming metadata encoded using the XML schema defined in ISO 19115-3 (this Technical Specification) into an XML-encoded ISO 19115 metadata document using the ISO 19139 XML schema (this transform will not include all content in the 19115-1 document).

== Implementation benefits ==
This standard specifies the implementation of ISO 19115-1:2014, Geographic information – Metadata – Part 1: Fundamentals, in XML, using parts of the GML, which is defined in ISO 19136:2007, Geographic information – Geography Markup Language (GML). While this standard is still a draft and hence likely to change, it should not change significantly as ISO 19115-1:2014 has already been published. The benefit of implementing ISO 19115-3 will be to access all the metadata encoded using it, and to promote one’s products and services by providing one’s metadata to clearinghouses using ISO 19115-3 for disseminating metadata.

However, this does not mean that the only way to implement ISO 19115-1:2014 is through XML, as defined in ISO 19115-3. ISO 19115-1 can be implemented in databases and GISs, and encoded using other markup languages such as JSON or GeoJSON, interchange formats such as ISO/IEC 8211 or ASN.1, or even as comma-separated values (CSV).

In the same way that ISO 19115-1:2014 replaces ISO 19115:2003, while leaving a legacy of much metadata conforming to ISO 19115:2003, ISO 19115-3 will replace ISO/TS 19139:2007, Geographic information – Metadata – XML schema implementation (the XML implementation of ISO 19115:2003) as the preferred XML schema implementation, but will not invalidate all the metadata already generated that conforms to ISO 19139:2007. ISO 19115-3 also specifies the XSLT (Extensible Stylesheet Language Transformation) for converting metadata from ISO 19139:2007 to ISO 19115-3 and vice versa, though converting from ISO 19115-3 to ISO 19139:2007 will obviously lose that content not defined in ISO 19139:2007. ISO 19139:2007 also defines some general rules and is being revised to cater for them, and not the XML schema implementation of metadata.

== Implementation guidelines ==
ISO 19115-3 implements the entire UML model from ISO 19115-1:2014, through a collection of XML schema that conform to ISO 19118:2011, Geographic information – Encoding, and ISO 19139:2007. The XML schemas are derived algorithmically from the UML. Unsurprisingly, the standard requires a sound knowledge of XML to understand it.

Clause 6.1 provides an overview of the XML schema for geospatial metadata. Clause 5.2 specifies the namespaces used in this standard, clause 5.4 the UML model stereotypes, clause 6.2 the multi-lingual adaptability and polymorphism, and clauses 6.3, 6.4, 6.5 and 6.6 the requirements classes. Clause 6.7 shows in a diagram, the dependencies between encoding requirements classes.

Clause 7 provides the model extensions defined in ISO 19139:2007. Clause 8 provides the encoding rules, which are also described in ISO 19139:2007. Annex D provides encoding descriptions and Annex E provides some implementation examples.

The actual XML will probably be provided in an online repository, rather than just printed out in the standard.