Rules From On High - Drools/BRMS in the Cloud

Hello, and welcome to my talk.

Today we will learn about Drools, why you should care about Drools, and how to strategically utilize Drools synergisticly in your next enterprise cloud microservice architecture. We'll also move a little dude around a map.

Things we will not talk about

BPMS
Business Central
OptaPlanner
Drools Fusion

So what is Drools, and why do I care?

Business rules engine
Declarative Programming
- say what? not how
- solve otherwise impossible problems w/ explanation
- Knowledge Base as documentation
Separate your business logic from data
- vs. OO which combines data with their logics
- easier to maintain, change, adapt
- easier to understand logic that crosses domains
  - clean rules files instead of messy controllers
Cloud ready
- small footprint, very containerable
- KIE-Server REST interface
- PHREAK algorithm easily scales across threads

Cool! But how does it work?

Rete

PHREAK

Too much theory. Can you show me something real?

Rules Rule

package org.some.package.name

rule 'Some rule name'

when
    // conditions
then
    // actions

end

Let's make it more real. Say we have two POJOs:

public class Weather {
    private boolean isRaining;

    // getters + setters 
}

public class Thing {
    private boolean isWet;

    // getters + setters 
}

package class.logic.example

rule "Things get wet outside"
when 
    Weather( raining )
    $t : Thing()
then
    $t.isWet( true );
end

Cross Product

There can be lots of Things. If we aren't careful, we may be comparing every Thing to every other possible Thing. So we need to be more specific. This is variable contraint.

rule when $thing : Thing() $

Salience
Inference
KnowledgeAgent (maybe drop)

This is airy stuff. You said it runs in the cloud?

Yes! Let me demonstrate.

First, let's hop on a cloud (read: someone else's computer) and pull down the official containers.

We're going to need two: the Drools Workbench

docker pull jboss/drools-workbench-showcase

And KieServer

docker pull jboss/kie-server-showcase

This may take awhile. I already did this on my machine, so let's keep going.

Next, we start it:

docker run -p 8080:8080 -p 8001:8001 -d --name drools-workbench jboss/drools-workbench-showcase:latest

docker run -p 8180:8080 -d --name kie-server --link drools-wb:kie_wb jboss/kie-server-showcase:latest

herbertkb / drools-dungeon