Consistency: global or partial ?
- wonderful for users and their programs
- too many interacting sources
- long time to achieve, 2 sources (UAL, LH), 3 (+ trucks), 4, … all ?
- costly maintenance, since all sources evolve
- no world-wide authority to dictate conformance
Domain-specific ontologies XML DTD assumption
- Small, focused, cooperating groups
- high quality, some examples - arthritis, Shakespeare plays
- allows sharable, formal tools
- ongoing, local maintenance affecting users - annual updates
- poor interoperation, users still face inter-domain mismatches
- periodic source updates need automation in interoperation