dc-text: a simple text-based format for dc metadata
DESCRIPTION
A description of DC-Text, a text format for the representation of DC metadata description sets. Short paper presented to DC-2006 Conference, Manzanillo, Colima, Mexico on 3 October 2006.TRANSCRIPT
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Pete Johnston & Andy Powell, Eduserv [email protected]
[email protected]/foundation
DC-Text: a simple text-based format for DC metadata
DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico
3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico
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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
3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico
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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
3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico
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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
Resource URI
Property URI Rich representation
Property URI Value URI Vocab Enc Scheme URI
Property URIValue 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
3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico
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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
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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
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DC-Text: Syntactic Structure
label ( label ( content ) label ( label ( content ) ))
• 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 ) ) ))
http://example.org/person/fred
URIs abbreviated as Qualified Names
@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:[email protected]> ) ) ))
(“Related”) description of value linked by id/idref
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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?
3 O
ctob
er 2
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Pete Johnston & Andy Powell, Eduserv [email protected]
[email protected]/foundation
DC-Text: a simple text-based format for DC metadata
DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico