Drools

Drools is actually made up of several other projects like Guvnor (Business Rules Manager), Expert (rule engine), 5jBPM 5 (process/workflow), Fusion (event processing/temporal reasoning) and Planner (automated planning).

Features:

• Engine features:
• Full Rete Implementation -with high performance indexing
• Dynamic RuleBases
• Stateful and Stateless Execution Modes
• Async operations
• Rete and Sequential Rete
• Rule Agent
• Optional Data Shadowing
• Pluggeable Dialects
• Propositional Logic features:
• Literal Restriction
• Variable Restriction
• Return Value Restriction
• Jointed and dis-jointed Connectives allowed '&&' '||'
• inline-Eval
• First Order Logic (Quantifiers) features:
• And
• Or
• Exists
• Not
• Accumulate
• Collect
• From
• Forall
• Nesting of any CE inside of 'and' and 'or'
• Support for both infix and prefix 'and'/'or' CEs
• Nesting and Chaining of 'from', 'accumulate', 'collect'
• Execution Control features:
• Conflict Resolution (salience) Now pluggeable
• Agenda Filters
• Agenda Groups
• Activation Groups
• Rule Flow
• Attributes (no-loop, lock-on-active)
• Temporal Rules
• Scheduler for rule duration will fire when a rule is true for X duration
• Truth maintenance with Logical Insertions
• Event Model features:
• Working Memory, Agenda and Rule Flow
• Configurable
• All Rete optimizations and execution behavior can be configured
• Authoring
• Technical rules: DRL and XML formats supported
• Template based DSLs
• Guided Editor
• BRMS and Eclipse
• Decision Tables (Excel, Open Office)
• BRMS (Knowledge Asset Management System)
• Authoring and Storage DRLs, RuleFlows, Decision Tables, Business Rules (Guided Editor)
• Multi level Versioning, at both the rule and package level
• Classification
• Deployment
• Built on Standards and Open APIs JCR (JSR 170) Dublin Core, GWT