Integrating OpenL Tablets with a Spring Boot Microservice

This post explains how to integrate OpenL Tablets with your Spring Boot microservice. We’ll cover adding the necessary dependencies, configuring OpenL Tablets, and creating a service to use it.

1. Project Setup and Dependencies

Begin by creating a Spring Boot project. Then, add the following OpenL Tablets dependencies to your pom.xml (Maven) or build.gradle (Gradle) file:

Maven:

XML

<dependency>
    <groupId>org.openl.rules</groupId>
    <artifactId>org.openl.rules.ruleservice</artifactId>
    <version>5.27.8</version>
</dependency>
<dependency>
    <groupId>org.openl.rules</groupId>
    <artifactId>org.openl.rules.ruleservice.spring</artifactId>
    <version>5.27.8</version>
</dependency>

Gradle:

Gradle

implementation 'org.openl.rules:org.openl.rules.ruleservice:5.27.8'
implementation 'org.openl.rules:org.openl.rules.ruleservice.spring:5.27.8'

2. OpenL Tablets Configuration

Create a configuration class to set up OpenL Tablets. This class will define a bean for org.openl.rules.ruleservice.loader.RulesLoader and configure the location of your Excel spreadsheet rules.

Java

import org.openl.rules.ruleservice.loader.JcrRulesLoader;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class OpenLTabletsConfig {

    @Bean
    public JcrRulesLoader rulesLoader() {
        JcrRulesLoader rulesLoader = new JcrRulesLoader();
        rulesLoader.setWorkspace("default"); // Your JCR workspace
        rulesLoader.setRulesLocation("/rules"); // Location of your rules in the workspace
        return rulesLoader;
    }
}

This configuration:

• Creates a JcrRulesLoader which loads rules from a JCR repository.
• Sets the workspace and rulesLocation properties to specify where your rule files are located. You’ll likely need to adjust these based on your setup.

3. Create OpenL Tablets Rule Files

Create an Excel spreadsheet with your rules defined in OpenL Tablets format. For example, discount.xlsx:

This simple table defines discount rules based on the total price of an order.

4. Deploying Rule Files

You need to deploy your Excel spreadsheet rule files to your JCR repository (e.g., Jackrabbit). The specific deployment process will depend on your JCR repository setup.

5. Using OpenL Tablets in a Service

Inject the RulesLoader bean and use org.openl.rules.ruleservice.RuleService to execute rules against your domain objects.

Java

import org.openl.rules.ruleservice.RuleService;
import org.openl.rules.ruleservice.loader.RulesLoader;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class OrderService {

    @Autowired
    private RuleService ruleService;

    @Autowired
    private RulesLoader rulesLoader;

    public Order applyRules(Order order) throws Exception {
        // Make sure the rules are loaded
        rulesLoader.reload();

        // Execute the rule
        Object result = ruleService.execute("discount", "getDiscount", new Object[] { order }); 

        // Assuming the rule returns a double representing the discount
        order.applyDiscount((Double) result); 
        return order;
    }
}

This service:

• Injects the RuleService and RulesLoader.
• Calls rulesLoader.reload() to ensure the latest rules are loaded.
• Executes the getDiscount method from the discount rule file (your Excel spreadsheet).
• Applies the returned discount to the order.

6. YML Configuration (Optional)

You might need to configure your JCR repository connection details in your application.yml or application.properties file.

This guide provides a basic framework for integrating OpenL Tablets with your Spring Boot microservice. You can expand on this by exploring more advanced OpenL Tablets features and integrating them with your business logic. Remember to adapt the rules and domain models to your specific requirements.