Validator Implementation Report

From rifle

W3C Implementation Report for RIF Validator. Answers to the questionnaire:

1. Your name, affiliation, and (optionally) the names of other people who helped with the implementation.
   • Jose María Álvarez (Fundación CTIC)
   • Luis Polo (Fundación CTIC)
2. The name of your system, a URL for its website (if any), and a one-sentence description.
   • RIFle Validator
   • Web page: http://idi.fundacionctic.org/rifle
   • Description: RIFle validator is a tool for checking the syntactic correcteness of a RIF document.
3. Which dialects your software is designed to support (eg Core, BLD, PRD, or non-standard extension dialects). We would appreciate some brief commentary about why you chose these dialects, and what sorts of implementation techniques (eg algorithms) are being used.
   • Actually, it only supports RIF-Core, although it is planned to extend its scope to also cover RIF-PRD. We have chosen these RIF dialects because we are interested in production rules, especially in the combination of producion rules with RDF/OWL. As these combinations are based on the combination between RIF-Core and RDF simple entailment, we have started building a RIF-Core validator. This approach also ensures interchange of rules independently of the paradigm chosen, as it is common subset between logical programming and production systems.
   • The validator uses JAXB to marshall and unmarshall RIF XML documents into Java Objects. The validator implements the Visitor pattern to process the XML file. Moreover, Jena framework in conjunction with Pellet reasoner are used to check semantic web compatibility.
4. Do you believe your system currently conforms to the RIF Candidate Recommendations? Does it pass all the test cases for your dialect(s)? If not, which features does it lack and/or which test cases does it not yet pass? Do you have plans to make it conformant, and make it pass all the test cases?
   • The RIFle validator is conformant with the RIF-Core RC, although it doesn't pass yet all the testcases, as it is an alpha release. Our plan is to be fully conformant with the specification. However, please notice that the validator only checks the syntactic correctness of a RIF-Core document. Entailment related issues are out of the scope of this tool, thus there may be test cases that do not apply.
   • XML report file (11th November, 2009).
5. Does it implement any parts of RIF RDF and OWL Compatibility? Any issues?
   • Yes, the validator checks the syntactic conformance of a RIF-Core document which imports RDF graphs according to the specified profile. With respect to the RDF files, they are loaded using Jena framework. However, there is a strong limitation when RDF data are accesible via a SPARQL endpoint. We do not support these issues yet, and we think this is an issue that must be taken into account if we want RIF to be useful for Linked Data applications.
   • The validator only accepts RDF N-triples syntax. RIF testcases also use this syntax. It would be great to have testcases in RDF/XML normative syntax. This is important for implementation, because it must be specified to Jena the format of the RDF file.
6. Did you implement the "at risk" features? If not, do you intend to, or do you think we should remove them from RIF?
   • No. We suggest to remove or to fully add them to specification, otherwise they might be confusing because it is not clear whether they are part of the standard.
7. Finally, we'd appreciate your evaluation of whether the RIF Candidate Recommendation is ready to proceed along the standards track toward being a W3C Recommendation. If not, please be sure to tell us what problems you think we need to address.
   • We support the idea to continue with the process for W3C recommendations. The implementation of a validator and our intentions to continue working on this direction are clear evidences. Moreover, there are some issues we are working on, and we will try to provide feedback as soon as possible.