DC-Text: a simple text-based format for DC metadata DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico

DC-Text: a text format for DC metadata Context & motivation DCMI Abstract Model DCMI “encoding guidelines” DC-Text Basic structure Features Some reflections, issues still to be discussed

Context & motivation

DCMI Abstract Model

DCMI “encoding guidelines”

DC-Text

Basic structure

Features

Some reflections, issues still to be discussed

Why DC-Text? Context & Motivation Historical separation of DC description model from representation/encoding “ Grammatical Principles” v “Encoding Guidelines” Formalised in development of DCMI Abstract Model DCMI Recommendation March 2005 DCAM describes Components and constructs that make up an information structure (“DC description set”) How that information structure is to be interpreted DCAM does not describe how to represent a DC description set in concrete form

Historical separation of DC description model from representation/encoding

“ Grammatical Principles” v “Encoding Guidelines”

Formalised in development of DCMI Abstract Model

DCMI Recommendation March 2005

DCAM describes

Components and constructs that make up an information structure (“DC description set”)

How that information structure is to be interpreted

DCAM does not describe how to represent a DC description set in concrete form

DCAM Description Model a description set is made up of one or more descriptions a description is made up of zero or one resource URI and one or more statements a statement is made up of exactly one property URI and zero or one reference to a value in the form of a value URI zero or more representations of a value, each in the form of a value representation zero or one vocabulary encoding scheme URI a value representation is either a value string or a rich representation a value string may have an associated value string language a value string may have an associated syntax encoding scheme URI a value may be the subject of a related description

a description set is made up of one or more descriptions

a description is made up of

zero or one resource URI and

one or more statements

a statement is made up of

exactly one property URI and

zero or one reference to a value in the form of a value URI

zero or more representations of a value, each in the form of a value representation

zero or one vocabulary encoding scheme URI

a value representation is either

a value string or

a rich representation

a value string may have an associated value string language

a value string may have an associated syntax encoding scheme URI

a value may be the subject of a related description

Resource URI Property URI Rich representation Property URI Value URI Vocab Enc Scheme URI Property URI Value string Syntax Enc Scheme URI Value string Syntax Enc Scheme URI Resource URI Property URI Rich representation Property URI Value URI Vocab Enc Scheme URI Property URI Value string Syntax Enc Scheme URI Statement Description Description Set

Why DC-Text? Context & Motivation DCMI “Encoding Guidelines” specs Pre-date development of DCAM Use earlier, simpler “DC abstract models” Not fully compatible with DCAM description model Currently, no machine-readable format for full DCAM description model Updating of specs in progress (2006) Also, demand for human-readable format Examples to support discussion of DCAM Examples in “encoding guidelines” documents Similar role for N3, Turtle etc for RDF model

DCMI “Encoding Guidelines” specs

Pre-date development of DCAM

Use earlier, simpler “DC abstract models”

Not fully compatible with DCAM description model

Currently, no machine-readable format for full DCAM description model

Updating of specs in progress (2006)

Also, demand for human-readable format

Examples to support discussion of DCAM

Examples in “encoding guidelines” documents

Similar role for N3, Turtle etc for RDF model

Design Principles Plain text format Avoid complexity of XML, XML Namespaces etc Easily human-readable, human-writable Suitable for use in e.g. email, Wiki pages Support full DCAM description model DC-Text document = single description set Clear (to human reader) representation of DCAM description model Conciseness not major consideration But support useful abbreviation mechanisms where possible

Plain text format

Avoid complexity of XML, XML Namespaces etc

Easily human-readable, human-writable

Suitable for use in e.g. email, Wiki pages

Support full DCAM description model

DC-Text document = single description set

Clear (to human reader) representation of DCAM description model

Conciseness not major consideration

But support useful abbreviation mechanisms where possible

DC-Text: Syntactic Structure label DescriptionSet Description ResourceURI Statement PropertyURI etc label ( label ( content ) label ( label ( content ) ) ) content label (content) “ literal” <URI> prefix:name language tag description id/idref

label

DescriptionSet

Description

ResourceURI

Statement

PropertyURI

etc

content

label (content)

“ literal”

<URI>

prefix:name

language tag

description id/idref

DescriptionSet ( Description ( ResourceURI ( <http://example.org/page/home> ) Statement ( PropertyURI ( <http://purl.org/dc/elements/1.1/title> ) ValueString ( “My Home Page” Language ( en ) ) ) Statement ( PropertyURI ( <http://purl.org/dc/elements/1.1/creator> ) ValueURI ( <http://example.org/person/fred> ) ) ) Description ( ResourceURI ( <http://example.org/person/fred> ) Statement ( PropertyURI ( <http://xmlns.com/foaf/0.1/knows> ) ValueURI ( <http://example.org/person/tom> ) ) ) )

@prefix dc <http://purl.org/dc/elements/1.1/> . @prefix foaf <http://xmlns.com/foaf/0.1/> . @prefix page <http://example.org/page/> . @prefix person <http://example.org/person/> . DescriptionSet ( Description ( ResourceURI ( page:home ) Statement ( PropertyURI ( dc:title ) ValueString ( “My Home Page” Language ( en ) ) ) Statement ( PropertyURI ( dc:creator ) ValueURI ( person:fred ) ) ) Description ( ResourceURI ( person:fred ) Statement ( PropertyURI ( foaf:knows ) ValueURI ( person:tom ) ) ) ) URIs abbreviated as Qualified Names http://example.org/person/fred

@prefix dc <http://purl.org/dc/elements/1.1/> . @prefix foaf <http://xmlns.com/foaf/0.1/> . @prefix page <http://example.org/page/> . DescriptionSet ( Description ( ResourceURI ( page:home ) Statement ( PropertyURI ( dc:title ) ValueString ( “My Home Page” Language ( en ) ) ) Statement ( PropertyURI ( dc:creator ) DescriptionRef ( fred ) ) ) Description ( DescriptionId ( fred ) Statement ( PropertyURI ( foaf:mbox ) ValueURI ( <mailto:fred@example.org> ) ) ) ) (“Related”) description of value linked by id/idref

Some reflections, issues Several conventions taken from Turtle (Dave Beckett) Draft circulated to DCMI Architecture WG (May 2006) Used for human-readable examples in DC in XML, DC in RDF drafts DCMI IEEE LTSC Task Force documents supporting email discussions DC-Text as machine-readable format? BNF provided Use YAML? Use JSON?

Several conventions taken from Turtle (Dave Beckett)

Draft circulated to DCMI Architecture WG (May 2006)

Used for human-readable examples in

DC in XML, DC in RDF drafts

DCMI IEEE LTSC Task Force documents

supporting email discussions

DC-Text as machine-readable format?

BNF provided

Use YAML?

Use JSON?

DC-Text: a simple text-based format for DC metadata DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico