Frameworks Frameworks

Standardised Metadata Frameworks

The main problem related to the use of the standardised metadata description schemes is the fixed number of describing attributes and their specialisation on fixed domains with the consequent lesser flexibility in representing needs of particular application domains.
In the light of these difficulties another standard class has been evolved, considering the possibility of integrating more metadata standards mapped on different application domains, providing rich metadata models for media descriptions together with languages allowing the definition of other description schemes for arbitrary domains.
These last standards can be referred as standardised metadata frameworks. They promised simpler interoperability among different application domains and also the possibility to simpler create generic tools able to process multimedia descriptions.
We can summarise the main characteristics of the standardised metadata frameworks in the following points:
This section shows some of reference metadata standard frameworks described classifying them according to relevant characteristics [4].
Particular attention has been given to one of the latest initiative following this tendency which is represented by the MPEG-21, a new MPEG metadata standard framework still under development.
The following table shows a resume of the reference metadata standard frameworks.

PICS MCF RDF XTM
Standardisation body World Wide Web Consortium (W3C) World Wide Web Consortium (W3C) World Wide Web Consortium (W3C) TopicMaps.org Consortium
Year 1996 1997 1999 2001
Data Model Attribute based Semantic network based/directed labelled graphs Semantic network based/directed labelled graphs Semantic network based/directed labelled graphs
Schema Definition Language Rating Systems Standard vocabulary RDF Schema Topic Map Constraint Language (TMCL)
Domain Qualitative rating og web resources Machine understandable, semantic description of web resources Machine understandable, semantic description of web resources Semantic mapping of information resources
Level Semantic Semantic Semantic Semantic
MM type Any Any Any Any

Some characteristics of some reference metadata standard frameworks