New technologies are currently advancing the Semantic Web, based on the data semantics of XML and RDF. An advantage of RDF is that data from diverse sources can, in principle, be freely merged and repurposed. Yet we cannot expect meaningful results from simply merging previously unseen RDF data under an existing application. We need to be able to easily state new meanings, at the application level. Since much of the world’s data is in SQL, we need to work with application semantics over hybrid RDF-SQL data.
Rule systems offer an agile way of doing this. Yet, reasoning with rule systems over the web is a conceptually complex process. To bring order to this process, it is useful to focus on three kinds of semantics early on:
- Semantics1 is "Data Semantics" as in XML or RDF.
- Semantics2 specifies what a reasoning engine should do.
- Semantics3 concerns the Application Semantics in the meaning of English concepts at the author- and user-interface.
We use examples to describe a system that supports Application Semantics. For accountability, the system can explain, in business level English, results that it obtains from RDF or SQL. Anyone can use a browser to view, run and change the examples. Shared use of the system, at reengineeringllc.com , is free.