Rulette
Pragmatic business rule management

Me...
Kislay Verma
Bangalore, India
12 years of code @ Uber | Myntra | D.E. Shaw

What are business rules?

Jargon
Rule : IF order status=”cancelled” AND refunded=”false”, THEN
action=”doRefund”.
Rule Input : “order status”, “refunded” in the above example.
Rule Output : “action” in the above example.

Jargon
Rule : Mapping of “n” rule inputs to 1 output
Rule System : System with ability to manage rules and evaluate them against an input.

Jargon

Business Rules in Excel-speak

Rule Engines

Problems with Drools
1. Cognitive Modelling Mismatch
2. Too much flexibility at the cost of expression
3. No data types
4. How to handle “Any”/”Others”?
5. Large set-up

Enter Rulette...
1. Talks the same language as your business
2. Works out-of-the-box
3. Rule management and evaluation
4. Lightweight with minimal boilerplate
5. Completely extensible with custom data types and data sources

When not to use Rulette
1. Rules go beyond “equals”, “less than”, and “greater than”.
2. The output logic is complicated - genuine ad-hocness.
3. Maintaining a set-up is not a problem.

Rulette Components

Rulette : Core Entities
Rule System
a. Id
b. Name
c. Table name
d. Output column name
e. Input column name

Rulette : Core Entities
Rule Input
a. Rule system id
b. Name
c. Rule Input Type
d. Rule Input Data Type
e. Priority
f. Low threshold column name
g. High Threshold column name

Rulette : Consistency Semantics
1. Rule Input Data Types : Number, Date, String
2. Rule Input Input Types : Value, Range
3. Value inputs can’t all be equal for 2 rules.
4. Ranges can’t overlap partially, one should completely contain another
5. Output : Always String, interpret however you want

Rulette : Stitching things

Case Studies

Modelling GST (Taxes)

Core Entities

Core Entities

Setting up the rules

Modelling Discounts

What next?
1. Support for databases other than MySql.
2. Clustering Support for In-Memory Rulette.
3. Evolving Rulette REST server.
4. Admin UI.

Reference
1. Github - https://github.com/kislayverma/Rulette/wiki
2. Javadoc - https://github.com/kislayverma/Rulette/wiki/Javadoc