Generic handling of metadata/Technology basics
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Concept[edit]
Discussion Points[edit]
- exact requirements (known data/unknown data), use cases
- defining structure, screen config and vocabulary mapping in one file or separated
- technology decision
- restrictions on incoming data
Requirements in General[edit]
- view
- edit
- search
- store in repository
- define metadata
- define interoperable metadata (resources and statements)= compatibility to RDF, DCAP
- encoding schemes (controlles vocabulary, syntax restrictions)
- mapping to Standard vocabulary terms
- screen configuration
- label
- positioning
- occurence
- form element
- validation of data against a schema/DSP
- additional requirements see known data
Requirement Matrix[edit]
| Requirements\Data | Unknown data | Known data |
| view | + | + |
| edit | + | + |
| search | + | + |
| Screen configuration | + | + |
| store in repository | + | + |
| define Metadata in general | ? | + |
| define interoperable metadata (resources and statements) | ? | + |
| define encoding schemes | ? | + |
| define Mapping to Standard Vocabulary Terms | ? | + |
| Validation of data against a schema | - | + |
Data to handle (Known Data/Unknown Data)[edit]
- Definition (Known data):
- xml format (only well-formed and valid xml???)
- schema or DSP is available
- related concepts: Handling of Semistructured Data might be interesting[1] ???
- Definition (Unknown data):
- heterogenous or unstructured data
- any format
- no schema od DSP available
Considered Techologies[edit]
RDF/RDFS[edit]
RDF Data Model
- triples consisting of resources (literal or non-literal) and statements/properties
- subject predicate object. where subject and object are resources, predicate is statement
- described structure is a directed graph
Syntax/Language
- Data: variants of rdf triple syntax, xml syntax
- Schema: RDFS [2] (XML Syntax)
RDF Sample 1:
http://example.org/einstein ex:name "Albert Einstein".
- resources: http://example.org/einstein (non-literal, uri), "Albert Einstein" (literal)
- statements: ex:name
RDF Sample 2:
http://example.org/einstein ex:affiliation http://example.org/mpdl.
http://example.org/mpdl ex:name "MPDL".
- resources: http://example.org/mpdl, http://example.org/einstein, "MPDL"
- statements: ex:name, ex:affiliation
Rules/Validation
- RDFS can be extended to Web Ontology Language (OWL)[3]
- 2 versions of OWL:
- OWL Lite: definition of classes/subclasses for resources and properties, property range and domain, only cardinality 0 and 1 allowed (occurence)
- OWL DL: OWL Lite + set operations (intersect, union, complement), unrestricted cardinality, enumeration classes, disjoint classes
XML, XML Schema, Relax NG[edit]
Data Model
- described structure is a ordered tree (graph possible with references)
- basic components: elements and attributes
- difference to RDF, DSP: basic components are just syntactical constructs, they don't give any information about the content
Syntax/Language
- Data: XML
- Schema: XML Schema, Relax NG, maybe also Schematron
Description Set Profile: DC-DS-XML, DSP[edit]
Data Model
- basic components: resources (or classes), properties and constraints (Vocabulary Encoding Scheme, Syntax Encoding Scheme)
Syntax
- for Data (Instances): DC-DS-XML [4], DC-Text Syntax [5]
- for Definition/Schema: DSP-XML [6], DSP-RDF [6], DSP-WIKI [7], DC-Text Syntax [5]
DSP-XML Sample 1:
<?xml version="1.0" ?>
<DescriptionSetTemplate xmlns="http://dublincore.org/xml/dc-dsp/2008/03/31">
<DescriptionTemplate ID="http://example.org/einstein" minOccurs="1" maxOccurs="1" standalone="yes">
<ResourceClass>http://xmlns.com/foaf/0.1/Person</ResourceClass>
<StatementTemplate minOccurs="1" maxOccurs="1" type="literal">
<Property>http://example.org/name</Property>
</StatementTemplate>
</DescriptionTemplate>
</DescriptionSetTemplate>
DC-DS-XML Sample 1:
<?xml version="1.0" encoding="UTF-8" ?>
<dcds:descriptionSet xmlns:dcds="http://purl.org/dc/xmlns/2008/09/01/dc-ds-xml/">
<!-- Description Element -->
<dcds:description dcds:resourceURI="http://example/einstein">
<dcds:statement dcds:propertyURI="ex:name">
<dcds:literalValueString>Albert Einstein</dcds:literalValueString>
</dcds:statement>
</dcds:description>
</dcds:descriptionSet>
Overview (pros and cons)[edit]
| Requirements\Technology | RDF/RDFS | XML/XSD/RelaxNG | DSP |
| describe interoperable Metadata/compatibility with DCAP, RDF | implicit (+) | possible, but not implicit (-) | implicit (+) |
| Screen config | -- | -- | -- |
| Technology/Tool Support | -- | -- | -- |
| Mapping to Standard Vocabulary Terms | -- | -- | -- |
| Validation mechanism | -- | -- | -- |