Business Delegate Pattern

1. Introduction

The Business Delegate Pattern is a design pattern that acts as a middleman between the client and the business service. It is used to decouple the client from the business service and to reduce the complexity of the client interface.

2. Definition

The Business Delegate Pattern is a structural design pattern that provides a simplified interface to a complex subsystem. This is particularly useful in applications where multiple services need to be accessed, providing a single point of contact for the client.

3. Key Concepts

Decoupling: Separates the client and the service layer.
Abstraction: Provides a simplified interface for the client.
Flexibility: Facilitates changes in the service layer without affecting the client.

4. Structure

The main components of the Business Delegate Pattern include:

Client: The user interface or application that requires services.
Business Delegate: The intermediary that communicates with the business service.
Business Service: The actual service that performs business logic.
Lookup Service: A service that locates the business service for the business delegate.

5. Implementation

Below is a simple implementation of the Business Delegate Pattern in Java:


                // Business Service Interface
                public interface BusinessService {
                    void doProcessing();
                }

                // Concrete Business Service
                public class EJBService implements BusinessService {
                    @Override
                    public void doProcessing() {
                        System.out.println("Processing task by invoking EJB Service");
                    }
                }

                // Business Delegate
                public class BusinessDelegate {
                    private BusinessService businessService;
                    private String serviceType;

                    public void setServiceType(String serviceType) {
                        this.serviceType = serviceType;
                    }

                    public void doTask() {
                        if (serviceType.equalsIgnoreCase("EJB")) {
                            businessService = new EJBService();
                        }
                        businessService.doProcessing();
                    }
                }

                // Client
                public class Client {
                    private BusinessDelegate businessDelegate;

                    public Client(BusinessDelegate businessDelegate) {
                        this.businessDelegate = businessDelegate;
                    }

                    public void doTask() {
                        businessDelegate.doTask();
                    }
                }

                // Main
                public class Main {
                    public static void main(String[] args) {
                        BusinessDelegate businessDelegate = new BusinessDelegate();
                        businessDelegate.setServiceType("EJB");
                        Client client = new Client(businessDelegate);
                        client.doTask();
                    }
                }

6. Best Practices

When implementing the Business Delegate Pattern, consider the following best practices:

Avoid tight coupling by using interfaces for services.
Use a lookup service to dynamically resolve services.
Keep the business delegate lightweight and focused on communication.

7. FAQ

What is the main benefit of using the Business Delegate Pattern?

The Business Delegate Pattern provides a clear separation between the client and service layers, simplifying communication and reducing the complexity of the client.

Can the Business Delegate Pattern be used in RESTful services?

Yes, the Business Delegate Pattern can be adapted for use with RESTful services to manage communication between the client and the REST API.

Is the Business Delegate Pattern suitable for all applications?

While it is beneficial for large applications with complex service interactions, it may introduce unnecessary overhead in simpler applications.