Building an English-based Rules Engine Using .NET and IronRuby

@KeithElder

Director, Software Engineering @ Quicken Loansor

Aka: Professional Emailer and Typer

Quicken Loans

WHAT AMAZES YOU?

ARE RULE ENGINES AMAZING?

What We’ll Be Doing Today

RUBY C#

If answer to question 2 is Very Satisfied and client is a repeat client then send them a discount coupon in the mail.Cylinde

r

A business rules engine is a software system that executes one or more business rules in a runtime production environment. It enables these company policies and other operational decisions to be defined, tested, executed and maintained separately from application code.

A deterministic rule engine may forgo both forward chaining and backward chaining, and instead utilize Domain-specific language approaches to better describe policy. This approach is often easier to implement and maintain, and provides performance advantages over forward or backward chaining systems.

Real World Example

You know what would be amazing? If I could create a way for someone in Marketing to enter rules just like above.

DEMO

What This Is Not

• Natural language processing• Machine learning

What It Is

• Ignoring the ceremony of the English language and taking only the parts we care about

• Pattern matching• Mapping the text to Code

HOW DOES IT WORK?

First – Identify Connectors

If answer to question 2 is Very Satisfied and client is a repeat client then send them a discount coupon in the mail.

CONNECTORS

Easier to Process

If answer to question 2 is Very Satisfied And client is a repeat client Then send them a discount coupon in the mail.CONNECTORS

If Statement

If answer to question 2 is Very Satisfied

Need a method that returns a bool and takes two parameters

bool AnswerToQuestion(int num, string ans)

If answer to question (\d+) is (.+)

And Statement

And client is a repeat client

Need a method that returns a bool with no parameters

bool ClientIsARepeatClient()

Then Statement

Then send them a discount coupon in the mail

Need a method that returns void with no parameters

void SendDiscountCoupon()

From English To Code

if AnswerToQuestion(2, “Yes”) && ClientIsARepeatClient() { SendDiscountCoupon() ;}

If answer to question 2 is Very Satisfied and client is a repeat client then send them a discount coupon in the mail.

Now We Have Our Mapping

[If(@"answer to question (\d+) is (.+)")] bool AnswerToQuestion(params string[] args)

[And(@"client is a repeat client")] bool ClientIsARepeatClient()

[Then(@"send them a discount coupon in the mail")] void SendDiscountCoupon()

If answer to question 2 is Very Satisfied And client is a repeat client Then send them a discount coupon in the mail.

We Created A RuleSetclass public SurveyRuleSet{

[If(@"answer to question (\d+) is (.+)")] public bool AnswerToQuestion(params string[] args) {}

[And(@"client is a repeat client")] public bool ClientIsARepeatClient() {}

[Then(@"send them a discount coupon in the mail")] public void SendDiscountCoupon() {}

}

SERIOUSLY DUDE WHERE’S THE RUBY, THAT’S THE ONLY REASON I’M HERE

CONVERTING ENGLISH TO RUBY

What Do We Know?

• Statements• Which functions those statements

map to

DEMO

Cool Features

• Support for variances in the language

• Could support any language, it’s just text after all

• Allows us to define our own DSL

DEMO – RULES FOR THE SOUTH, OTHER LANGUAGES AND LANGUAGE VARIANCES

Building an English-based Rules Engine Using .NET and IronRuby

@KeithElder

Director, Software Engineering @ Quicken Loansor

Aka: Professional Emailer and Typer