dmn-engine

Business-Rules Engine

Condition Symbols

• Column Value: $$ example DateDiff($$,@now)

• variable symbol: $example: $caseId this is needed since we allow multi words operations like starts with

• Is null value or empty: Null or Empty

• Any Value: -

• All types:

  • null or empty
  • not null
  • true or false

Type	Syntax	Examples
Numbers	value	500
	compare operator	>500
		<500
		between 500 and 700
String	value	Low-Income
	Quoted Value	'Low-Income'
	string operators	starts with 'Low'
		ends with 'Income'
		contains 'Income'
		not 'Low-Income'
Date	Quoted value	'2020/12/01'
	Date operators	after '2020/12/01'
		>30 days
		<10 years
		contains 'Income'
		not 'Low-Income'

Introduction

Is a Business Rules Engine supporting DMN Decision Tables. Allowing developers to integrate Rules into JavaScript or Node.js applications.

This solution utilizes deterministic rules vs Rete based solutions that are non-deterministic.

This package is designed specifically for Node.js and TypeScript

As an example of Decisition Table

Usage

Definition

Decision table can be defined as a JSON or CSV file

Invoke

To invoke the above example

    const Rules=requires('./business-rules.json')'
    const dt= Rules.load('client-category);
    let result=dt.run({type:'Private',  deposit: 500 , netWorth: 500});

    console.log(result.category);

Testing

    const tester=Rules.loadTest('./client-category-tests.json');
    let results=tester.run();
    console.log(results.summary);

UI for Testing and expeirmenting

Rule Syntax

Conditions

Expression Language

Simple Conditions shortcuts

• Literal values with or without quotes, so "high" and high are acceptable

• coditional operators and functions without referencing the variable like >500

• Empty Condition or - indicates all values are true

• For numeric variables:

  • 500

  • between 500 and 700

• For Date variables, functions like:

  • > 30 days , > 50 minutes , < 10 years etc.
  • before '2018/01/01' or after '2018/03/01'
  • between '2018/01/01' and '2019/12/31'

Complex Conditions

• And , Or and Not operators, brackets () can also be used
• complex operations and functions can reference the variable using @ symbol

Output

Output expressions can use the full expression language and reference any input or ouput variable.

Expression Engine

    const exp=new Expression(`2+3*4`);
    const result= expr.evaluate();
    console.log(result);

Expressions are compiled into AST

    const exp=new Expression(`2+3*4`);
    const compiled= expr.compile();

    // or reloaed

    const expr=Expression.load(compiled);
    const result= expr.evaluate();

    console.log(result);

Language Constructs

Literals

• Strings: 'John'
• Numbers: 123.25

Words

salary

customer.address

Operators

The package already defines a set of operators but you can add your own

Operator Symbols

+ -' * /` etcs.

Word Operators

between is defined as a word operator

Functions

Keywords

The following literals are defined as Keywords

-true -false -null