A Simple Rules Engine

For one of my project, I needed a simple rules engine.

I like the DecisionDag that Mandar Jog built. It uses Commons JEXL and allows rules to be defined in plain english.

In my use case, I had following goals.

keep it simple (KISS)
rules engine as micro-service (deployable to cloud).
a rules catalog of sorts that allowed new versions of the rules to be added and older ones removed.
ability to calculate within the rule and return results.

This is a simple rules engine built with spring-boot in java.

The rules are in plain javascript.

Nashorn sccript engine allows runtime loading and evaluation of rules.

Instructions

Install the app by cloning the repository rulesengine

Build and run the app

   $ cd rulesengine
   $ gradlew bootRun

Call rest end-points.

   $ curl -v 'http://localhost:8080/api/rules/WhatToDo?family_visiting=yes'
   
   $ curl 'http://localhost:8080/api/rules/WhatToDo?family_visiting=no&money=poor&weather=good'
   
   $ curl 'http://localhost:8080/api/rules/WhatToDo?family_visiting=no&money=poor&weather=cold'
   
   $ curl 'http://localhost:8080/api/rules/WhatToDo?family_visiting=no&money=rich&weather=cold'

Cloud

Meet PCF Dev. It is a simplifed, and minimized version of the Pivotal Cloud Foundry intended for your local machine. And Getting started is simple.

#####Deploy to cloud

Target the cloud instance

   $ cf login -a api.local.pcfdev.io --skip-ssl-validation

   API endpoint:  api.local.pcfdev.io   
   Email>     admin
   Password>  admin

Build and deploy to cloud

   $ cd rulesengine
   $ ./gradlew assemble
   $ cf push -f manifest.xml

Test the cloud service

   $ curl -v 'http://simplerules.local.pcfdev.io/api/rules/WhatToDo?family_visiting=yes'
   
   $ curl 'http://simplerules.local.pcfdev.io/api/rules/WhatToDo?family_visiting=no&money=poor&weather=good'
   
   $ curl 'http://simplerules.local.pcfdev.io/api/rules/WhatToDo?family_visiting=no&money=poor&weather=cold'
   
   $ curl 'http://simplerules.local.pcfdev.io/api/rules/WhatToDo?family_visiting=no&money=rich&weather=cold'

diamondbigdata/rulesengine

A Simple Rules Engine

Instructions

Cloud