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- Call For Participation -

W3C Workshop on
Rule Languages
for Interoperability

27-28 April 2005 — Washington, D.C., USA

Summary: Rule languages and rule systems are widely used in applications ranging from database integration, service provisioning, and business process management to loan underwriting, privacy policies and Web services composition. General purpose rule languages remain relatively unstandardized, however, and rule systems from different suppliers are rarely interoperable.

Meanwhile, the Web has achieved remarkable success in allowing documents to be shared and linked throughout the world. More recently, Semantic Web languages like RDF and OWL are beginning to support data/knowledge sharing on the same scale and with considerable flexibility. Having a language for sharing rules is often seen as the next step in promoting data exchange on the Web.

This workshop, held by W3C with support from DARPA and hosted by ILOG, is intended to gather various participants and inputs needed to see how a standard rule framework might be developed, informed by Web Architecture and useful for addressing real user challenges.

See workshop site for news and repository of contributed materials




Rules everywhere

Rules are everywhere. They are found in many domains, disciplines, and industries. Business policies, laws and regulations, guidelines and best practices, definitions and axioms, database schema translations, workflow branching and technical constraints, all require a declarative and modular approach to their implementation. There is a thriving commercial market in several families of rule technologies, including production rules, event-condition-action rules, Prolog, relational database systems, and others. However, practical interoperability between these systems, especially across the different families, is currently quite limited.

Rules are 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. Rules can themselves be treated as data, published on the web, and when URIs (or QNames) are used as symbol-constants in a rule language, they can form useful links between knowledge bases. In a Web services environment, rules offer the opportunity to enable the automation of the enforcement and composition of policies governing the delivery of information, the access to services, or the execution of processes.

Rules have advantages of flexibility and manageability. In addition, the declarative nature of rules gives them a special appeal as a programmatic and knowledge representation device in a distributed and Web-based environment, where they can be owned, specified and managed in one place, and applied in many other places. This requires, however, a standard way to represent rules unambiguously for publication and interchange purposes.

Different rules and a common foundation

Rules come in a variety of forms for different uses and applications. Business rules, decision tables, and decision trees are used to automate the enforcement of business policies and regulations. Logical formulas, constraints, ontologies, association and transformation rules are used for inferencing in information retrieval and information integration, including databases, and metadata repositories (e.g. Dublin Core Initiative), or in analytical, forecasting and/or optimization applications.

Rules, however, trace their roots back to formal logic. There, semantics can be represented via a logical model theory and inference can be based on logical proof theory. The most important de facto semantic standard is first order predicate calculus, unchanged for nearly a hundred years. In the last three decades, declarative logic programs have emerged as a complement to first order logic, and provided the foundation for the semantics of relational databases and many rule languages. Algorithmic techniques and theory for formal logic have been extended to enable, and semantically treat: procedural attachments for built-ins, tests, and actions; and non-monotonicity for negation-as-failure, defaults, inheritance, prioritization, updating, revision, and conflict handling.

Candidate Languages and related work

To be effective, practical, and deployable, a Web standard on rules needs to focus on the requirements of end users and the needs of rule technology providers. The goal of being able to transfer rulebases / knowledge bases, or simply to process them with different software, has helped motivate several important standardization or standards-proposing efforts including RuleML and SWRL, n3, Metalog, KIF and ISO Common Logic, ISO Prolog, and others. Some of those have been aimed at more or less specialized purposes, e.g., in the domains of Web Service policies (WS-Policy, WSPL, Policy RuleML, SWSL, WSML), access control and authorization (XACML, EPAL, P3P/APPEL), Business Rules (BRML, SRML), and other areas as well. Related standardization efforts have also started with respect to rule modeling (OMG's Business Semantics for Business Rules RFP and Production Rules Representation RFP) and rulebase execution (JSR 94 - Java API for Rules Engine).

Workshop Goals

This workshop is a step along the path to establishing a standard language framework to support rule system interoperation on the Web. It aims at gathering vendors, technologists, application developers and users to discuss and provide recommendations to the W3C regarding what is the best approach to the specification of a standard or family of standards for the public representation and exchange of rules on the Web, in terms of avoiding redundant efforts, of optimizing the potential for wide adoption, and of promoting consistency and interoperability between different applications or layers, while preserving their specific requirements.

The specific goals for this workshop are:

  1. Gather and refine use cases and requirements for a framework;
  2. Gather information about available technologies and relevant areas of practice and research;
  3. Help establish a common ground for this work as well as a community of possible participants;
  4. Understand priorities and time frames and gather information to establish a strategy and a calendar;
  5. Help organizations and individuals learn enough about this work to determine their level of commitment going forward.


The workshop is expected to result in the following deliverables:

These will be published on the workshop home page.

Scope of the Workshop

The scope of this workshop is restricted in order to make the best use of participants' time. In general, discussion at the workshop and in the position papers should stay focused on the workshop goals and deliverables.

In scope:

Out of scope:


Expected Audience

We expect several communities to contribute to the workshop:

Requirements for Participation

Position Papers

Position papers are the basis for the discussion at the workshop. These papers will also be made available to the public from the workshop site.


Position papers discussing applications are expected to focus on the requirements for the public representation and interchange of rules. Position papers discussing interchange formats are expected to focus on the requirements and types of application covered by the proposal. Position papers discussing specifications including a rule interchange format are expected to focus on that aspect and on how they could link to/import rules represented in other existing or emerging formats (or why they cannot). Position papers discussing general issues regarding rules interchange and rule systems interoperability are expected to focus on how relevant existing standards or proposal or parts of an approach can be reused, evolved, extended; on principles and architecture; on related efforts in other communities (OMG, JCP, ISO, RuleML, SWSI, WSMO, etc).


All papers should be 1 to 5 pages, although they may link to longer versions or appendixes. Papers should explain the participant's interest in the workshop, explain their position with respect to a standard for publishing and interchanging rules on the Web and include concrete examples of the kind of rules they are interested in.

Accepted position papers will be published on the public Web pages of the workshop. Submitting a position paper comprises a default recognition of these terms for publication. Allowed formats are (valid) HTML/XHTML, PDF, or plain text. Papers in any other formats (including invalid HTML/XHTML) will be returned with a request for correct formatting. Good examples of position papers can be seen in the QL'98 workshop.

The Program Committee may ask the authors of particularly salient position papers to explicitly present their position at the workshop to foster discussion. Presenters will be asked to make the slides of the presentation available on the workshop home page in HTML, PDF, or plain text.

Position papers must be submitted via email to team-rule-language-workshop-submit@w3.org no later than 18 March 2005. Early submissions are appreciated.

Workshop Organization

Workshop Chairs

Program Committee

At this time, the program committee is still being assembled. The list so far:


The workshop program will run from 8:30 am to 6 pm on both days.


ILOG, S.A. will host the workshop, although not in their own facilities.

Significant funding for organizing this workshop was provided by DARPA through the DAML program.


The workshop will be held in a conference facility (such as a hotel) to be determined, in the Washington, D.C. area. Details will be included with acceptance notification. See workshop site.

Important Dates

Date Event
15 February 2005 Call For Participation issued
18 March 2005 Deadline for position papers.
1 April 2005 Acceptance notification sent; Program released
15 April 2005 Deadline for registration
27 April 2005 Workshop Begins (8:30 AM)
28 April 2005 Workshop Ends (6 PM)

Sandro Hawke, Said Tabet, Christian de Sainte Marie, with help from Benjamin Grosof
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