1. Pete Johnston & Andy Powell, Eduserv Foundation pete.johnston@eduserv.org.uk andy.powell@eduserv.org.uk www.eduserv.org.uk/foundation 3 October 2006 DC-Text: a simple text-based format for DC metadata DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico

2. 3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico 2 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. 3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico 3 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

4. 3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico 4 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

5. Resource URI Property URIRich representation Property URIValue URIVocab Enc Scheme URI Property URI Value stringSyntax Enc Scheme URI Value stringSyntax Enc Scheme URI Resource URI Property URIRich representation Property URIValue URIVocab Enc Scheme URI Property URI Value stringSyntax Enc Scheme URI Statement Description Description Set

6. 3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico 6 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

7. 3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico 7 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

8. 3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico 8 DC-Text: Syntactic Structure label ( label ( content ) label ( label ( content ) ) label –DescriptionSet –Description –ResourceURI –Statement –PropertyURI –etc content –label (content) –“literal” – –prefix:name –language tag –description id/idref

9. DescriptionSet ( Description ( ResourceURI ( ) Statement ( PropertyURI ( ) ValueString ( “My Home Page” Language ( en ) ) ) Statement ( PropertyURI ( ) ValueURI ( ) ) Description ( ResourceURI ( ) Statement ( PropertyURI ( ) ValueURI ( ) )

10. @prefix dc. @prefix foaf. @prefix page. @prefix 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

11. @prefix dc. @prefix foaf. @prefix 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 ( ) ) (“Related”) description of value linked by id/idref

12. 3 October 2006DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico 12 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?

13. Pete Johnston & Andy Powell, Eduserv Foundation pete.johnston@eduserv.org.uk andy.powell@eduserv.org.uk www.eduserv.org.uk/foundation 3 October 2006 DC-Text: a simple text-based format for DC metadata DC-2006: Metadata for Knowledge & Learning, Manzanillo, Mexico