What is Rule Engine?

What is a Rule Engine?

Cask Distributed Rules Engine is a Rule Engine or a Production Rule System that uses the rule-based approach to implement an Expert System. Expert Systems are knowledge-based systems that use knowledge representation to process acquired knowledge into a knowledge base that can be used for reasoning.

A Production Rule System is Turing complete with a focus on knowledge representation to express propositional and first-order logic in a concise, non-ambiguous and declarative manner.

The brain of a Production Rules System is an Inference Engine that can scale to a large number of rules and facts. The Inference Engine matches facts and data against Production Rules – also called Productions or just Rules – to infer conclusions which result in actions.

A Production Rule is a two-part structure that uses first-order logic for reasoning over knowledge representation. A business rule engine is a software system that executes one or more business rules in a runtime production environment.

A Rule Engine allows you to define “What to Do” and not “How to do it.”

What is a Rule?

Rules are pieces of knowledge often expressed as, "When some conditions occur, then do some tasks."

When
    <Condition is true>
Then
    <Take desired Action>

The most important part of a Rule is its when part. If the when part is satisfied, the then part is triggered.

rule  <Rule Name> 
  When <Condition is TRUE>
  Then 
    <Take Action 1>
    <Take Action 2>
    ...
    <Take Action N>
  }   
}

Pattern Matching

The process of matching the new or existing facts against Production Rules is called Pattern Matching, which is performed by the Inference Engine. There are a number of algorithms used for Pattern Matching including:

• Linear
• Rete
• Treat
• Leaps

YARE currently implements Linear Algorithm for pattern matching, but, there is an effort in progress to implement Rete Algorithm.

What is a Rulebook ?

Logical grouping of Rules is called a Rulebook. Rules are the knowledge-base, but Rulebook are more of concept over the Rule to group them into Logical sets. E.g. Rulebook for handling PII data -- will contain all the rules associated with masking, encrypting fields of your data.

A Rulebook, provides a reference to collection of rules in addition to other metadata that is associated with the Rulebook like user who is building the Rulebook, etc.