rulesengine

Business Rules Engine

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rulesengine
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Readme

BizRez Rules - JavaScript Condition Event Engine

A small functional Rule Engine - simple maybe an understatement...

Intro

Simplicity is elegance. This rule engine is NOT forward chaining, backward chaining, nor is this an inference engine. What it is, is a pragmatic reactive engine. Simply stated, when there is a condition, execute an action -- most assuredly in a stateless manner.

Prime directives, and ables ...

  • Stateless
  • Simple input, output, and process
  • Asynchronous non-blocking invocations
  • Rules to be self contained and serializable to a database (persistable)
  • Rules to be versioned (versionable)
  • Rules to be inventoried and stored in a library (sharable)
  • Rules can be modified on-the-fly (adaptable)
  • Rules can be unit tested independently (testable)
  • Crazy fast

#####Martin Fowler on Rule Engines

// Rule Abilities 
{ables: [persistable, versionable, shareable, adaptable, testable, chainable, reusable, extensible]}

Dependencies

  • Underscore.js for Mapreduce Decision Tables
  • Async.js for asynchronous hooks and behavior
  • Mocha.js for for test infecting the code (good infection)
  • Require.js for the module loader

A few Use Cases for Usage

  • Validations
  • Mappings
  • Calculations
  • Batch processing
  • Automated business rules - decision engine
  • Automation of sequential events and process
  • Home security, sprinkler systems, and darn maybe your car...

Benefits

  • Repository of rules
  • Traceability
  • Modify the rule not the code
  • Dynamic changeability - conditions change so do the execution
  • Easy to understand and modify
  • Extensible
  • Maintainable
  • Reusable
  • Chainable
  • Micro foot print and scalable

Design - IPO (Input Process Output)

// Input - Example Greetings

facts = {
          input: { hour: 10 },
          output: {greeting:''}
         }

// Process - Example Decision Table
rule =  {

                "id": "GREETING",
                "description": "Show correct greeting based on time",
                "condition": function (facts) {
                    // We will calculate the results regardless
                    return true;
                },
                "action": function (facts) {

                    var decisionTable
                        = [
                        {from: 0, to: 11, greeting: 'Good Morning'},
                        {from: 12, to: 17, greeting: 'Good Afternoon'},
                        {from: 18, to: 22, greetings: 'Good Evening'},
                        {from: 23, to: 24, greetings: 'Good Night'}
                    ];

                    var resultArray;

                    // MAP
                    resultArray = _.map(decisionTable, function (row) {
                        var result = "";
                        if (facts.input.hour >= row.from && facts.input.hour <= row.to) {
                            result = row.greeting;
                        }
                        return result;
                    });
                    // Reduce
                    var result = _.reduce(resultArray, function (memory, element) {
                        if (element !== "") {
                            memory = element;
                        }
                        return  memory;
                    });
                    facts.output.greeting = result;

                }
            }
// Output - Example result

facts = {
          input: { hour: 10 },
          output: {greeting:'Good Morning'}
         }

Download

The source is available for download from GitHub.

Alternatively, you can install using Node Package Manager npm:

npm install rulesengine

mocha test

If you find any bugs or have a feature request, please open an issue on github!

The npm package download data comes from npm's download counts api and package details come from npms.io.