looking to build a java dynamic rule engine using easy rules api

Question

I have many rules to be evaluated against the data in our database, i am planning on using easyrules api. I dont prefer programming or hardcoding the rules within my code. It should be easy to change the rule criteria once the code is built. Pls assist me on how can i make it dynamic and readable. Easyrules api insists on having a separate class for each rule as below: I want the below code to be dynamically built based on easily modifiable rule input: I was thinking of the below but not sure which one is best: 1. DB table - a rule table with rule conditions. (I can use an update query to change the rules) 2. JSON or XML.

I am flexible on other tools too not confined to easyrules. https://github.com/j-easy/easy-rules/wiki/hello-world

/**
 * Hello World rule class.
 *
 * @author Mahmoud Ben Hassine ([email protected])
 */
@Rule(name = "Hello World rule", description = "Say Hello to duke's friends only")
public class HelloWorldRule {

    /**
     * The user input which represents the data that the rule will operate on.
     */
    private String input;

    @Condition
    public boolean checkInput() {
        //The rule should be applied only if the user's response is yes (duke friend)
        return input.equalsIgnoreCase("yes");
    }

    @Action
    public void sayHelloToDukeFriend() throws Exception {
        //When rule conditions are satisfied, prints 'Hello duke's friend!' to the console
        System.out.println("Hello duke's friend!");
    }

    public void setInput(String input) {
        this.input = input;
    }

Solution 1

I would probably suggest you go with java + groovySrcipt engine. You can provide your rules in GroovyScripts and can dynamically execute them using GroovyEngine. it just a thought.

Solution 2

This is an old question but by the end of 2017, Easy Rules can have dynamic rules by external files.

From their website:

name: "alcohol rule" 
description: "children are not allowed to buy alcohol" 
priority: 2 condition: "person.isAdult() == false" 
actions: - "System.out.println(\"Shop: Sorry, you are not allowed to buy alcohol\");"