XML and the DCMI Abstract Model

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XML and the DCMI Abstract Model DC Architecture
WG Meeting, DC-2005,Madrid, Spain, Monday 12
September 2005 Pete Johnston Research Officer,
UKOLN, University of Bath
UKOLN is supported by
www.bath.ac.uk
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DCMI Abstract Model and Bindings

• DCAM describes conceptual model for DC metadata
  description set
• types of construct
• relationships between constructs
• Description sets encoded/serialised as records
• Binding describes mapping between constructs in
  conceptual model to components in syntax
• Two way
• encoding application description set -gt record
• decoding application record -gt description set

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DCMI Abstract Model and XML

• DCMI provides multiple "encoding guidelines"
  specifications
• XHTML, RDF (Simple, Qualified), XML
• Guidelines for implementing Dublin Core in XML
  (2003)
• DCMI Recommendation
• XML binding for DC metadata
• Mapping between constructs in conceptual model to
  components in XML syntax
• XML elements (names, content),
• XML attributes (values)
• Other non-DCMI XML bindings for DC deployed

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DC-XML-2003 and DCMI Abstract Model

• DCAM Appendix C
• features of DCAM supported by DC-XML-2003
• However, DC-XML-2003 pre-dates DCAM
• maps conceptual models to XML
• but does not map DCAM to XML
• provides own models
• "Simple DC Record"
• "Qualified DC Record
• DC-XML-2003 models different from DCAM

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DC-XML-2003 models and DCMI Abstract Model (1)

• Same/similar concepts, different labels

DC-XML-2003 DCAM
"record" description
"property and associated value" statement
"value" value string
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DC-XML-2003 models and DCMI Abstract Model (2)

• Concepts present/omitted

DC-XML-2003 DCAM
resource URI
value URI
multiple value representations
rich representations
related descriptions
description sets
types of "record"
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DC-XML-2003 models and DCMI Abstract Model (3)

• Concepts conflated

DC-XML-2003 DCAM
"encoding scheme" vocabulary encoding scheme, syntax encoding scheme
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Problems

• Attempts to encode/decode conceptual constructs
  not present in DC-XML-2003 models
• resource URI
• value URI
• vocabulary encoding scheme/syntax encoding scheme
  distinctions

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DC-XML-2003 models and DC-XML-Binding (1)

• Syntax examples with no mapping to DC-XML-2003
  models (section 6)
• ODRL, IMS-LRM XML fragments
• XML sub-tree constructed according to rules of
  second XML format
• XML sub-tree has no interpretation in DC-XML-2003
• Contradicts rationale for specification
• error in specification?

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DC-XML-2003 models and DC-XML-Binding (2)

• Binding "encoding schemes" to XML Schema
  datatypes
• XML Schema datatypes apply to XML element
  content, XML attribute values
• syntax encoding schemes?
• but default type always present?
• Datatype derivation problems
• trying to introduce support for rich
  representations at syntax level

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Problems

• Section 6 encourages merging of arbitrary XML
  fragments
• hybrid document with no interpretation
• "undermines" mapping to DCAM!
• Mapping "encoding schemes" to XML Schema complex
  types
• can't work for both vocabulary encoding schemes
  and syntax encoding schemes
• Complex Type derivation problematic for some
  tools

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Proposal

• XML binding for DC explicitly based on DCAM
• subset of DCAM?
• full DCAM?
• including review of use of XML Schema datatyping
• Early drafts

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Questions

• Stay with (extended) DC-XML-2003?
• emphasise that supports simpler model?
• Maintain both (extended) DC-XML-2003 and
  DC-XML-2005?
• emphasise that different models supported
• Deprecate DC-XML-2003 and move towards support
  for DC-XML-2005 only?

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XML and the DCMI Abstract Model DC Architecture
WG Meeting, DC-2005,Madrid, Spain, Monday 12
September 2005 Pete Johnston Research Officer,
UKOLN, University of Bath
UKOLN is supported by
www.bath.ac.uk