au.com.agilepractices.rules.engine.examples:rules-engine-examples-hmrc-tax

Getting Started

To start playing with rules just add the dependency to your project: au.com.agilepractices.rules.engine:rule-engine-core:

Maven

<dependency>
    <groupId>au.com.agilepractices.rules.engine</groupId>
    <artifactId>rules-engine-core</artifactId>
    <version>${rules.version}</version>
</dependency>

Gradle

dependencies {
  compile "au.com.agilepractices.rules.engine:rules-engine-core:$rulesVersion"
}

A rule consists of:

• A Condition - which must evaluate to true or false
• An Action - which is executed if the Condition evaluates to true
• An optional alternative Action - which is executed if the Condition evaluates to false

Example

First step towards evaluation using the rule engine is to define a rule.

We can do it using:

• Java DSL

final Rule<String, String> rule = RuleBuilder.newRule()
        .when((input, ruleAuditor) -> true)
        .then(context -> context.setResult("Hello " + context.getData()))
        .build();

Then add the Rule to a RuleBook

RuleBook<String, String> ruleBook = RuleBook.newInstance(String.class, String.class)
        .add(rule);

To execute the RuleBook:

String result = new SimpleRuleExecutor<>(ruleBook)
        .execute("World");

assertThat(result).isEqualTo("Hello World");