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W3C has announced the formation of a new Rule Interchange Format (RIF) Working Group tasked with the challenge of producing a "standard means for exchanging rules on the Web. Rules constitute a key element of the Semantic Web vision, allowing integration, derivation, and transformation of data from multiple sources in a distributed, transparent and scalable manner."
The Rule Interchange Format WG has been chartered at least through November 2007 to "produce a core rule language plus extensions which together allow rules to be translated between rule languages and thus transferred between rule systems. The Working Group will have to balance the needs of a diverse community — including Business Rules and Semantic Web users — specifying extensions for which it can articulate a consensus design and which are sufficiently motivated by use cases."
According to Tim Berners-Lee, announcing the new activity at the Information Juggernaut event in Galway, Ireland, the chartered work builds upon the foundation of years of industry and research work in rules languages. "bringing together business rules vendors, user companies, rule language designers, and Semantic Web developers to create a rules standard as an important step in achieving the full power of the Semantic Web."
Creating a common Rule Interchange Format for the Web is expected to "provide a way to represent established and new rule languages, allowing rules written for one application to be published, shared, merged and re-used in other applications and by other rule engines. This in turn facilitates the integration of individual, departmental, corporate, and public data sources and the ability to draw new conclusions. A Rule Interchange Format will, for example, help businesses find new customers, doctors validate prescriptions, and banks process loan applications. With a Rule Interchange Format for the Web, conventional rules technology will be enhanced not only by the usual economies of standardization, but specifically by what the Semantic Web infrastructure provides: the ability to exchange and merge rules from different sources."
In the interest of interoperability and compatibility, the new W3C Working Group will "reuse and build on existing technologies and standards, even when this makes the design job harder." The charter acknowledges that the "greatest challenge in establishing a rule language standard may be the multitude of existing approaches in the marketplace. Interoperation with the most widely deployed technologies will be crucial for obtaining the desired standardization effect."
Specific compatibility goals are targeted for: (1) XML. "There is no standard mechanism for mapping XML data directly to semantic structures (e.g., relations); in Phase 2 the WG must address at least part of this challenge in specifying a way for rules to make use of XML data." (2) RDF. "RDF's design has considerable overlap with the condition/fact part of a rule language; both are ways of formally expressing propositions. In order to reduce unnecessary re-invention and incompatibilities, the Working Group must use the RDF Semantics as a starting point in the areas of overlap, justifying and agreeing to any variation. (3) SPARQL. "The WG should ensure the rule language is compatible with the use of SPARQL as a language for query of the dataset, that the extension mechanism is compatible with use of the SPARQL protocol for fetching additional datasets, and should aim for compatibility with SPARQL's use of XML datatypes, functions and operators." (4) OWL. "It is important that the Working Group maintain compatibility with OWL, allowing knowledge expressed in OWL and in rules to be easily used together."
Formation of the Rule Interchange Format (RIF) Working Group follows a number of preliminary research and coordination activities by W3C, including a successful Workshop on Rule Languages for Interoperability, held 27-28 April 2005 in Washington, D.C. The Workshop's program committee "accepted 71 papers and selected a subset of them for presentation; some 82 people attended the Workshop, representing vendors, user communities, and research groups. More than a dozen use cases were presented for rule language standardization, and about a half-dozen candidate technologies were presented and discussed. The workshop confirmed the differences among types of rules, such as 'if condition then action' rules and 'if condition then condition' rule types.
In Phase 1 the Rule Interchange Format Working Group will produce specifications for a very simple and yet useful and extensible format for rules. Phase 1 deliverables include: (1) a "Use Cases and Requirements" document; (2) a W3C Recommendation providing technical specifications of the interchange format, suitable for implementers of rule engines and rule language translation software; (3) a W3C Recommendation on using this rule interchange format in combination with OWL, designed to help show implementors and advanced users how these technologies overlap and the advantages and limitations around using them together; (4) a set of Test Cases which reflect issue resolution and which aid in conformance evaluation.
For Phase 2 the Working Group is chartered to produce Recommendations for standard extensions which are strongly motivated by use cases and for which it can articulate a consensus design. These designs will build on the Phase 1 specifications which establish the basic extensibility mechanism and produce a usable language; with that core, vendors and advanced users implementing applications around that format will generate additional use cases. Phase 2 Recommendations may be released separately, grouped into language "levels", as with CSS and DOM, or the Working Group may decide to use a combination of release strategies to maximize effective deployment."
The published Charter of the Rule Interchange Format Working Group discusses specific relationships of the work to external standards efforts, including RuleML, JSR 94: Java Rule Engine API, OMG Production Rule Representation (PRR), OMG Semantics of Business Vocabulary and Business Rules (SBVR), and ISO Common Logic (CL). The WG's relationships to other W3C tecnical areas and specifications are also addressed, including the W3C RDF Data Access Working Group (DAWG), the W3C XML Activity, and various W3C Submissions: Semantic Web Rule Language (SWRL), Semantic Web Rule Language First-Order Logic (SWRL FOL), Semantic Web Services Language (SWSL) — part of the Semantic Web Services Framework (SWSF), and the Web Rule Language (WRL).
Participation in the RIF Working Group is open to affilites of W3C Member organizations and (upon approval) to Invited Experts. The first face-to-face meeting of the Rule Interchange Format Working Group will be held 8-9 December 2005 at the Hyatt Regency, San Francisco Airport, co-located with OMG's technical meeting.
