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This is one of the possible Use Cases.

1. Abstract

RIF RuleML FOAF combines RDF-based FOAF with RIF RuleML, extending the factual FOAF vocabulary by RIF RuleML rules. Users can derive FOAF data by employing person-centric rules, either before (RDF) FOAF publication or, on demand, from published (RIF RuleML) FOAF pages.

2. Status

3. Links to Related Use Cases

4. Relationship to OWL/RDF Compatibility

OWL Compatiblity can be achieved as in SWRL or, with Hybrid Rules, as in the Realistic Architecture. RDF Compatiblity is achieved via the Fact-oriented Normal Form (see below).

5. Examples of Rule Platforms Supporting this Use Case

6. Benefits of Interchange

7. Requirements on the RIF

8. Breakdown

8.1. Actors and their Goals

8.2. Main Sequence

  1. Publishers create FOAF data in either of two ways:
  2. Rule-oriented Normal Form (RNF)
    • - The RNF includes rules as well as the (elementary) facts that are needed by the premises of the rules, omitting derivable facts - Advantage: the RNF is more compact
  3. Fact-oriented Normal Form (FNF)
    • - The FNF includes elementary facts and derived facts, but omits the rules - Advantage: the FNF (XSLT-)corresponds to RDF FOAF facts
  4. Readers come in corresponding variants:
  5. RNF Readers apply a rule engine to generate relevant FOAF facts on demand
  6. FNF Readers can retrieve raw facts or use any FOAF explorer on (XSLT-)translated RDF facts
  7. Subscribers are served much like returning, incremental Readers
  8. Harvesters periodically crawl Publishers' FOAF data according to specific collection criteria

8.3. Alternate Sequences

9. Narratives

Ben has created his person-centric metadata in the form of a FOAF document as has become popular, covering unconditional properties about his personal interests, friends, etc. However, he also needs to specify properties conditional on other persons, the time, the location, etc. For example, Ben prefers to specify his work time and free time s.t. his colleagues can contact him when at work, while his friends can reach him when off work. Consequently, with rules, his schedule might look as follows:

Monday - Friday

Saturday, Sunday, Holidays

10. Commentary

Given the importance of FOAF and RDF for the Semantic Web, this should become a central Use Case for a Semantic Web RIF. It will also permit the fact and rule based description of our own community of experts.