The latest rules conferences RulesFest-2011, BBC-2011, and RuleML-2011 were really great events in general and for OpenRules in particular. We announced a new constraint-based Rule Engine that is the first alternative to Rete-based implementations of a real inferencial rule engine.
The integrated Business Rules (BR) + Constraint Programming (CP) approach is supported by OpenRules Rule Solver for a while. However, a new Rule Solver can directly execute decision models and can automatically support the inference principles. It means the following:
1) The order of rules inside decision tables does not matter. You may insert new rules anywhere inside a decision table and the execution results will be the same (even if your decision table does not cover all possible combinations, i.e. rules are not necessarily mutually exclusive)
2) The order of decision tables does not matter. Rule Solver automatically resolves inferential dependencies between decision tables.
Rule Solver considers a decision model as a direct input for a constraint solver (without any preliminary conversion to a rule language or to a constraint engine). Additionally, Rule Solver can effectively validate decision models for conflicts and completeness (across ALL decision tables). Rule Solver reports all errors in business terms of the original decision model. It also goes beyond regular decision models allowing a user not to describe all possible combinations of fact types to come up with a decision: some fact types may remain not instantiated and Rule Solver will automatically find a feasible or an optimal decision.
You may get more details from this, just published paper: “Representing and Solving Rule-Based Decision Models with Constraint Solvers”, F.Olken et al. (Eds.): RuleML 2011 – America, LNCS 7018, pp. 208-221, 2011, Springer-Verlag Berlin Heidelberg 2011. It is downloadable from http://openrules.com/pdf/RuleML2011.JacobFeldman.pdf.
The latest Rule Solver is based on the JSR-331 standard and can utilize different open source constraint solvers. It is currently in a test mode, and will become publicly available by the end of this year.