Report on Work of Joint DCMI/IEEE LTSC Task Force

Update on work of Joint DCMI/IEEE LTSC Task Force CETIS Metadata & Digital Repositories SIG, UKOLN, Bath

Background

Metadata standards typically developed to support requirements of some community or domain

Resources used across community/domain boundaries

Implementers want

to use component parts of different standards in combination

to (re)use components of other implementers’ work

Concept of “ metadata application profile ” (e.g. Heery/Patel, Duval et al)

tailor standard to context

combine components from different standards (“mix & match”)

Abstract Models for Metadata

Abstract Model of metadata standard specifies

Nature of components and constructs used in standard

Set of rules for building abstract information structure

IEEE LOM Abstract Model

AIS = LOM instance

Data elements containing other data elements

“ Leaf” data element values associated with datatypes (how value spaces interpreted)

DCMI Abstract Model

AIS = DC description set

Description = set of statements about resource

Statement

references to property, value, vocabulary encoding scheme, syntax encoding scheme

value strings, value representations

Abstract Models & Application Profiles

Both DC and LOM have notions of “metadata application profile”…

… but based on respective Abstract Model

DC Application Profile

how to use a set of identified properties, vocabulary encoding schemes, syntax encoding schemes to construct a DC metadata description set

LOM Application Profile

how to use a set of identified LOM data elements, datatypes, vocabularies to construct a LOM instance

LOM conceptual data schema includes AM and a “base” application profile

Abstract Models & Bindings for Metadata

Abstract Models are syntax-independent

Bindings describe

how abstract information structure is serialised/encoded in a metadata format

how instances of a metadata format are interpreted in terms of abstract information structure

Both DC & LOM have bindings to XML formats

However, formats interpreted in terms of different Abstract Models

e.g. XML element parent-child relationships have different interpretations in LOM-XML and DC-XML

System A DC Description Set DC-XML Instance Encode using Binding Construct using DCAM & DCAP Decode using Binding DC Description Set Interpret using DCAM System B DC-XML Instance <?xml version="1.0"?> <dcx:descriptionSet>

System A Encode using Binding Construct using LOM AM & LOM AP Decode using Binding Interpret using LOM AM System B <?xml version="1.0"?> <lom:LOM> LOM Instance LOM Instance LOM-XML Instance LOM-XML Instance

The problem

IEEE LOM standard and Dublin Core based on different Abstract Models

LOM data elements and DC properties/classes can not be used in combination in same information structure

Earlier work on DC-LOM interoperability focused on RDF

mapping LOM to RDF

mapping DC to RDF

Not generalisable to other DC formats

The proposed solution

Develop a LOM-DCAM mapping

“ LOM data elements” => “instances of DCAM components/constructs”

Interpretation of LOM semantics in terms of DCAM

Not a binding for LOM, but a translation

lossy in part

one-way translation

Approach

conceptualise LOM as Entity-Relationship model

build on earlier work for LOM RDF binding

represent E-R model in terms of DCAM constructs

specify required terms, assign URIs

LOM Conceptual Data Schema Dublin Core Abstract Model DC-RDF Instance DC-XML Instance conforms to conforms to bound to translate (lossy) bound to LOM Instance DC Description Set LOM-XML Instance DC Description Set Combined DC Description Set

Outcomes

View of LOM as a basic DC Application Profile

Availability of set of “LOM terms” which are usable in other DCAPs

Availability of RDF binding of LOM “for free” via DC RDF binding (mapping)

Separation of LOM-DCAM translation from RDF binding

First step towards better alignment of DC and LOM abstract models?

Joint DCMI/IEEE LTSC Task Force

Initiated at DC2005 in Madrid, Sep 2005

Reports to DC Education WG & IEEE LTSC

Chairs: Mikael Nilsson & Jon Mason

Participation open to all:

mailing list (~20 subscribers), Wiki

Joint:

Collaborative work on drafts

Joint consensus

Co-publishing of results

Aim: an IEEE “Recommended Practice” and a DCMI “Recommendation”

Charter approved by DCMI Advisory Board and IEEE LTSC SEC

Draft PAR Scope & Purpose presented to LOM WG (March 2006)

Three initial outputs available for discussion:

Draft of LOM-DCAM mapping

includes description of DCAP

Example instance based on mapping

LOM XML

DC Text

Draft of required property/class/value definitions

folllowing DC “Schema Model”/Usage Board conventions

LOM-XML

DescriptionSet (

Description (

ResourceURI ( <http://purl.org/poi/rdn.ac.uk/12345-67890> )

Statement (

PropertyURI ( dc:title )

ValueString ( “Wilfred Owen and Realism”

Language ( en-GB )

)

)

Statement (

PropertyURI ( dc:language )

ValueString ( “en-GB”

SyntaxEncodingSchemeURI ( dcterms:RFC3066 )

)

)

Statement (

PropertyURI ( lom:keyword )

VocabularyEncodingSchemeURI ( a:NLS )

ValueString ( "Owen, Wilfred"

Language ( en-GB )

)

)

)

)

<lom> <general> <identifier> <catalog>URI</catalog> <entry>http://purl.org/poi/rdn.ac.uk/12345-67890</entry> </identifier> <title> <string language="en-GB">Wilfred Owen and Realism</string> </title> <language>en-GB</language> <keyword> <string language="en-GB">Owen, Wilfred</string> </keyword> </general> </lom> DC-Text

Other related DCMI work