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ISO/IEC PDTR 29111: Information Technology – Topic Maps

Expressing Dublin Core Metadata Using Topic Maps

Working Draft, 2007-06-25

Authors: Steve Pepper, Sam Oh, Patrick Durusau

0. Scope

The Dublin Core Metadata Initiative (DCMI) has produced one of the most successful vocabularies for expressing document metadata and is in widespread use on the World Wide Web, in libraries, and in many other areas. DCMI vocabularies are defined as sets of abstract elements and terms; the syntactic expression of these elements and terms is technology dependent.

This Technical Report defines a standard way of expressing Dublin Core metadata using ISO/IEC 13250 Topic Maps. Its purpose is to ensure a uniform approach to the application of Dublin Core among users of Topic Maps and thus enable seamless integration and improved knowledge aggregation. It covers both the general case of expressing Dublin Core metadata sets and the specific case of assigning Dublin Core metadata to topic maps, i.e., to topic maps viewed as what Dublin Core calls “described resources”.

All four term sets described in [DCMT] are covered, i.e., the Dublin Core Metadata Element Set, Other Elements and Element Refinements, Encoding Schemes, and the DCMI Type Vocabulary.

1. Normative references

[13250-2]

ISO/IEC 13250-2:2006 Topic Maps – Data Model

[15836]

ISO 15836: 2003 Information and documentation – The Dublin Core metadata element set

[DCAM]

DCMI Abstract Model, 2007-06-04, http://dublincore.org/documents/abstract-model/

[DCMT]

DCMI Metadata Terms, 2006-12-18, http://dublincore.org/documents/dcmi-terms/

2. Definitions

For the purposes of this Technical Report the definitions given in ISO/IEC 13250-2 apply.

The following terms defined in [DCAM] are reproduced here for convenience:

property

A specific aspect, characteristic, attribute, or relation used to describe resources.

property/value pair

The combination of a property and a value, used to describe a characteristic of a resource.

resource

Anything that might be identified. Familiar examples include an electronic document, an image, a service (for example, "today's weather report for Los Angeles"), and a collection of other resources. Not all resources are network "retrievable"; for example, human beings, corporations, concepts and bound books in a library can also be considered resources.

syntax encoding scheme

A set of strings and an associated set of rules that describe a mapping between that set of strings and a set of resources. The mapping rules may define how the string is structured (for example DCMI Box) or they may simply enumerate all the strings and the corresponding resources (for example ISO 3166).

value

The physical entity, conceptual entity or literal (a resource) that is associated with a property when a property-value pair is used to describe a resource.

value string

A literal, optionally associated with either a syntax encoding scheme URI or a value string language. In a literal value surrogate a value string encodes the value; in a non-literal value surrogate a value string represents the value.

value string language

An ISO language tag that indicates the language of the value string.

vocabulary encoding scheme

An enumerated set of resources.

3. The DCAM and the TMDM

This Clause describes basic equivalences between the Dublin Core Abstract Model and the Topic Maps Data Model and how concepts are mapped from the one to the other.

3.1 General principles

For the purpose of this Technical Report, a resource in Dublin Core is deemed to be equivalent to a subject in Topic Maps.

The assignment of metadata in the form of property-value pairs to Dublin Core resources is deemed to be the equivalent of making statements about a subject in Topic Maps.

Associations are used to represent property-value pairs whenever possible, which is to say in all cases except those case of:

1. elements that are naming properties (which are represented as topic names);

2. elements whose values consist of descriptive text or structured data types (which are represented as occurrences).

All such associations are binary and use the following pair of role types:

• Role played by the described resource: http://psi.topicmaps.org/iso29111/resource

• Role played by the resource that is the value of the property-value pair: http://psi.topicmaps.org/iso29111/value

When assigning Dublin Core metadata to a topic map, the topic map must first be reified. Statements are then made about the resulting topic.

3.2 Mapping the concepts of the DCAM

[DCAM] describes models for resources described by descriptions and for metadata description sets. The concepts of these models are mapped to concepts of the Topic Maps Data Model as follows:

• A DC described resource is represented by a topic item.

• A DC property-value pair is represented by a Topic Maps statement (i.e., a name item, occurrence item or association item, as specified in Clause 4).

• The property of a DC property-value pair is represented by the [type] property of the statement to which it gives rise.

• The value of a DC property-value pair is represented either by a topic item or by the [value] property of a name or occurrence item, as specified in Clause 4.

• A DC vocabulary encoding scheme or syntax encoding scheme is represented by the [datatype] property of an occurrence item.

• A DC value string language is represented by a [scope] property that consists of a single topic representing the language in question.

4. Dublin Core Metadata Terms

This Clause specifies the Topic Maps representation of every element and term in [DCMT].

4.1 The Dublin Core Metadata Element Set

The following table shows the kind of Topic Maps construct to which each term in the Dublin Core Metadata Element Set should be mapped. The prefix dc is used to represent the URI http://purl.org/dc/elements/1.1/.

DC Term Name	TM representation
contributor	association of type dc:contributor
coverage	association of type dc:coverage
creator	association of type dc:creator
date	occurrence of type dc:date
description	occurrence of type dc:description
format	association of type dc:format
identifier	occurrence of type dc:identifier
language	association of type dc:language
publisher	association of type dc:publisher
relation	association of type dc:relation
rights	occurrence of type dc:rights
source	association of type dc:source
subject	association of type dc:subject
title	name of type dc:title
type	association of type dc:type

4.2 Other Elements and Element Refinements

The following table shows the kind of Topic Maps construct to which each term in the metadata set Other Elements and Element Refinements should be mapped. The prefix dct is used to represent the URI http://purl.org/dc/terms/.

DC Term Name	TM representation
abstract	occurrence of type dct:abstract
accessRights	occurrence of type dct:accessRights
accrualMethod	association of type dct:accrualMethod
accrualPeriodicity	association of type dct:accrualPeriodicity
accrualPolicy	association of type dct:accrualPolicy
alternative	name of type dct:alternative
audience	association of type dct:audience
available	occurrence of type dct:available
bibliographicCitation	occurrence of type dct:bibliographicCitation
conformsTo	association of type dct:conformsTo
created	occurrence of type dct:created
dateAccepted	occurrence of type dct:dateAccepted
dateCopyrighted	occurrence of type dct:dateCopyrighted
dateSubmitted	occurrence of type dct:dateSubmitted
educationLevel	occurrence of type dct:educationLevel
extent	occurrence of type dct:extent
hasFormat	association of type dct:hasFormat
hasPart	association of type dct:hasPart
hasVersion	association of type dct:hasVersion
instructionalMethod	occurrence of type dct:instructionalMethod
isFormatOf	association of type dct:isFormatOf
isPartOf	association of type dct:isPartOf
isReferencedBy	association of type dct:isReferencedBy
isReplacedBy	association of type dct:isReplacedBy
isRequiredBy	association of type dct:isRequiredBy
issued	occurrence of type dct:issued
isVersionOf	association of type dct:isVersionOf
license	occurrence of type dct:license
mediator	association of type dct:mediator
medium	occurrence of type dct:medium
modified	occurrence of type dct:modified
provenance	occurrence of type dct:provenance
references	association of type dct:references
replaces	association of type dct:replaces
requires	association of type dct:requires
rightsHolder	association of type dct:rightsHolder
spatial	association of type dct:spatial
tableOfContents	occurrence of type dct:tableOfContents
temporal	association of type dct:temporal
valid	occurrence of type dct:valid

4.3 Encoding Schemes

Each term in the metadata set Encoding Schemes is represented by a topic whose subject identifier is the same as the URI of the term in question.

4.4 The DCMI Type Vocabulary

Each term in the metadata set DCMI Type Vocabulary is represented by a topic whose subject identifier is the same as the URI of the term in question.