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Created: November 09, 2005.
News: Cover StoriesPrevious News ItemNext News Item

Business Rules and Web Architecture: W3C Creates Rule Interchange Format WG.

Contents

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.

From the Announcement

[On November 7, 2005] the World Wide Web Consortium announced the formation of the Rule Interchange Format (RIF) Working Group with a mission to produce 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.

"After years of industry and research work in rules languages, I'm pleased to see W3C Members working to develop a Web-based rules standard," explained Tim Berners-Lee, Director of the W3C. "The bringing together of business rules vendors, user companies, rule language designers and Semantic Web developers to create a rules standard is an important step in achieving the full power of the Semantic Web."

Rules Standard Adds Power to Business Applications

Today's announcement marks a key step in bringing together the leaders in business rules development, Semantic Web developers, and end users in an effort to identify requirements for a common Rule Interchange Format for the Web. A Rule Interchange Format will 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.

Business Rules Become More Powerful When Coupled with Web Architecture

Linking the vision of the dynamic business rules marketplace with Web architecture began with the successful April 2005 W3C Workshop on Rule Languages for Interoperability, which brought together over sixty industry and research organizations working in this area including ILOG, Fair Isaac, Pegasystems, IBM, Oracle, Agfa, GM and others. The new W3C RIF Working Group is designed to balance the needs of a diverse community and produce a core rule language plus extensions which together allow rules to be translated between rule languages and thus transferred between rule systems.

More information is available from the W3C Rule Interchange Format home page.

Major funding for this work was provided by DARPA, as part of the DAML program, under MIT/AFRL cooperative agreement number F30602-00-2-0593.

From the Rule Interchange Format WG Charter

Mission. The Working Group is to specify a format for rules, so they can be used across diverse systems. This format (or language) will function as an interlingua into which established and new rule languages can be mapped, allowing rules written for one application to be published, shared, and re-used in other applications and other rule engines.

Because of the great variety in rule languages and rule engine technologies, this common format will take the form of a core language to be used along with a set of standard and non-standard extensions. The Working Group is chartered to first establish the extensible core and possibly a set of extensions, and then (in Phase 2) to begin to specify additional extensions based on user requirements. These extensions need not all be combinable into a single unified language.

This mission is part of W3C's larger goal of enabling the sharing of information in forms suited to machine processing, as seen in several application areas presented at the 2005 W3C Workshop on Rule Languages for Interoperability:

  • Rules themselves represent a valuable form of information for which there is not yet a standard interchange format, although significant progress has been made within the RuleML Initiative and elsewhere. Rules provide a powerful business logic representation, as business rules, in many modern information systems.

  • Rules are often the technology of choice for creating maintainable adapters between information systems.

  • As part of the Semantic Web architecture, rules can extend or complement the OWL Web Ontology Language to more thoroughly cover a broader set of applications, with knowledge being encoded in OWL or rules or both.

Phase 1 Scope.

  • Extensibility: "The essential task of the Working Group in Phase 1 is to construct an extensible format for rules. The Working Group must try to keep in mind the various features and usage scenarios for rule languages, to be sure the right kind of extensibility is in place... Some such features discussed at the workshop and probably of wide interest include: (1) Handling uncertain information, such as with fuzzy logic [Fuzzy Extension of SWRL, and FuzzyRuleML], (2) Modal Logics, probably including facilities for temporal logic..."

  • Conformance: "We do not expect rule engines or other rule processing systems (such as editors) to handle even a large set of the features standardized by this Working Group. There are many viable rule languages and rule engines which do not handle even all the Phase 1 features. (In particular, it is common to implement only function-free Horn Logic (Datalog), which is has a finite deductive closure..."

  • Load-and-Query Rule Engine: "The core rule engine functionality is to load zero or more rulesets (or datasets) and then answer zero or more queries against the merged contents. This functionality is largely independent of engine implementation strategies. In particular, it works with both forward chaining and backward chaining... The Working Group must not specify an engine control or query interface (language, protocol, or API) as part of the Phase 1 specifications, although it is expected to make use of some interfaces as part of the test suite and in examples..."

  • XML Syntax: "In order to allow interoperability with RDF and object-oriented systems, the syntax must support named arguments (also called 'role' or 'slot' names), allowing n-ary facts, rules, and queries to be provided through property/value interfaces. Note that the natural overlap in expressivity between this language and RDF means this syntax should function as an alternative XML serialization for RDF Graphs (or at least a subset of RDF Graphs)..."

  • Horn Logic: "The Phase 1 rule semantics will be essentially Horn Logic, a well-studied sublanguage of First-Order Logic which is the basis of Logic Programming... The language must include a way to express facts as well as rules, and also metadata (annotations) about documents, facts, and rules. The WG should consider the benefits of expressing this metadata in RDF, including the ability to query it with SPARQL and analyze it with rules A notion of "ruleset" may also be supported...."

  • Datatype Support: "Datatypes need support in the language, including both a syntax for literals and a set of common functions and operators. Most of the design and selection work here has been done as part of XML Schema and XML Query... In Phase 1, the format must support literals and common functions and operators for at least: text strings (xsd:string), 32-bit signed integers (xsd:int), unlimited-size decimal numbers (xsd:decimal), Boolean values xsd:boolean), and list structures..."

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