Business Delegate Design Pattern in Java

In this article, I am going to discuss Business Delegate Design Pattern in Java with Examples. Please read our previous article where we discussed MVC Pattern in Java. In this article, we will explore the Business Delegate Design Pattern in Java, its advantages, disadvantages, and practical applications in modern software development.

What is Business Delegate Design Pattern?

In the world of software development, managing complex business logic and interactions with various services can be a challenging task. The Business Delegate design pattern offers a solution to abstract away the complexities of interacting with multiple services, providing a centralized point of access.

The Business Delegate design pattern separates the client’s presentation logic from the complexities of accessing and interacting with multiple business services. It encapsulates the process of communication, error handling, and protocol-specific details, allowing the client to focus on the core business logic.

Components of Business Delegate Design Pattern

The pattern consists of the following components:

Business Delegate: It is the main component that acts as an intermediary between the client and the business services. The Business Delegate is responsible for abstracting the service lookup, invocation, and error handling. It shields the client from the underlying implementation details of service communication.
Service Locator: It is responsible for the lookup and retrieval of the business services. The Service Locator hides the complexities of locating and initializing the appropriate service objects. It can be used to provide caching mechanisms or load-balancing strategies.
Business Service: It represents the actual business logic or service implementation. Multiple business services can exist, each providing specific functionality. These services are typically accessed through interfaces, which the Business Delegate interacts with.

Example to Understand Business Delegate Design Pattern in Java

Let’s consider a real-world example where the Business Delegate Design Pattern can be applied: a payment processing service. Imagine a software system that handles payments for an e-commerce platform. The system needs to communicate with multiple payment gateways based on customer preferences and availability.

In this scenario, the Business Delegate acts as an intermediary between the client application and the payment gateways. The client application delegates the payment processing task to the Business Delegate, which abstracts away the complexities of interacting with different payment gateways.

The Service Look Up component is responsible for looking up and retrieving the appropriate payment gateway implementation based on configuration or user preferences. It maintains a registry of available payment gateways and their corresponding implementations.

The Business Service represents the payment gateway implementations, each providing specific functionality for processing payments. The Business Delegate interacts with the Service Locator to retrieve the required payment gateway implementation and performs the necessary actions, such as initiating the payment, validating payment information, and handling responses.

By using the Business Delegate design pattern in this payment processing service, the client application can remain decoupled from the specific payment gateways. The delegate shields the client from the complexities of gateway selection, communication protocols, and error handling. It provides a unified interface for processing payments, regardless of the underlying payment gateway being used.

This approach offers flexibility and maintainability. New payment gateways can be added or existing ones can be replaced without affecting the client application. The Business Delegate and Service Locator handle the necessary configuration and communication details, allowing the client application to focus on the core business logic.

Overall, the Business Delegate design pattern proves valuable in scenarios where there is a need to interact with multiple services and abstract away the complexities of service communication. The payment processing service example demonstrates how the pattern can provide a centralized point of access, enhance code organization, and promote scalability and flexibility in software systems. The UML Diagram of this example is given below using Business Delegate Design Pattern.

Implementing Business Delegate Design Pattern in Java

Step 1: Create a new directory to store all the class files of this project.

Step 2: Open VS Code and create a new project, called businessdelegate.

Step 3: In the project, create a new file called BusinessService.java. Add the following code to the file:

public interface BusinessService
{
    public void process();
}

This is the interface from which other concrete classes will extend.

Step 4: In the project, create two new files called ServiceA.java and ServiceB.java. Both of these files extend from the BusinessService interface. Add the following code to the files:

ServiceA.java

public class ServiceA implements BusinessService
{
    @Override
    public void process()
    {System.out.println("Service A processing!");}
}

ServiceB.java

public class ServiceB implements BusinessService
{
    @Override
    public void process()
    {System.out.println("Service B processing!");}
}

Step 5: In the project, create a new file called BusinessLookUp.java. This class is responsible for returning the appropriate process based on the client’s requirements. Add the following code to BusinessLookUp.java:

public class BusinessLookUp
{
    public BusinessService getBusinessService (String s)
    {
        if (s.equalsIgnoreCase("service a"))
            return new ServiceA();
        else if (s.equalsIgnoreCase("service b"))
            return new ServiceB();
        else
            return null;
    }    
}

Step 6: In the project, create a new file called BusinessDelegate.java. This class is responsible for handling the service object. Add the following code to BusinessDelegate.java:

public class BusinessDelegate
{
    private BusinessLookUp blu = new BusinessLookUp();
    private String service;

    public BusinessDelegate(String service)
    {this.service = service;}
    
    public void doTask()
    {blu.getBusinessService(service).process();}
}

Step 7: In the project, create a new file called Client.java. This class represents a client. Add the following code to Client.java:

public class Client
{
    BusinessDelegate bd;

    public Client(BusinessDelegate bd)
    {this.bd = bd;}
    
    public void doTask()
    {bd.doTask();}
}

Step 8: In the project, create a new file called BusinessDelegatePatternDemo.java. This class will contain the main() function. Add the following code to BusinessDelegatePatternDemo.java:

public class BusinessDelegatePatternDemo
{
    public static void main(String[] args)
    {
        new Client(new BusinessDelegate("service a")).doTask();
        new Client(new BusinessDelegate("service b")).doTask();
    }    
}

Step 9: Compile and execute the application. Ensure compilation is successful. Verify that the program works as expected.

Congratulations! You now know how to implement business delegate patterns!

UML Diagram of Business Delegate Design Pattern:

Now, let us see the Business Delegate Design Pattern UML Diagram Components with our Example so that you can easily understand the UML Diagram.

The classes can be described as follows:

BusinessService: This is the interface that will define the basic methods that will be implemented by the concrete business service class.
ConcreteBusinessService: This class implements the BusinessService interface. It implements the functions defined in the interface.
BusinessLookUp: This class is responsible for generating the proper type of resource, based on the client request.
BusinessDelegate: This class is responsible for communication between the client and the service.
Client: This class represents the client.
DriverClass: This class contains the main() function and is responsible for the simulation of the program.

Advantages of Business Delegate Design Pattern in Java:

The followings are the advantages of using the Business Delegate Design Pattern in Java:

Abstraction of Service Lookup: The Business Delegate design pattern abstracts away the complexities of locating and initializing business services. The client no longer needs to know the details of service discovery, such as service names, endpoints, or protocols. The Service Locator component centralizes this logic, making it easier to manage and modify service configurations.
Centralized Error Handling: With the Business Delegate acting as an intermediary, error handling can be centralized in one place. The delegate can handle exceptions, retries, and fallback mechanisms, shielding the client from the complexities of error management. This promotes code reuse, as error-handling logic does not need to be duplicated across multiple client components.
Encapsulation of Service Communication: The Business Delegate encapsulates the communication and interaction with the business services. It abstracts away protocol-specific details, such as REST, SOAP, or messaging formats. This allows the client to focus solely on the business logic, without being concerned with the intricacies of service communication.
Loose Coupling and Scalability: The Business Delegate design pattern promotes loose coupling between the client and the business services. Changes in the service implementation or underlying technologies can be isolated within the delegate and service locator, minimizing the impact on the client code. This loose coupling enhances scalability, as new services can be easily added or existing ones can be replaced without affecting the client’s codebase.
Code Reusability: The Business Delegate pattern facilitates code reusability by encapsulating the service interaction logic. The delegate can be reused by multiple client components, promoting consistency and reducing code duplication. This abstraction simplifies the development and maintenance of client applications, resulting in improved code quality.

Disadvantages of Business Delegate Design Pattern in Java:

The followings are the disadvantages of using the Business Delegate Design Pattern in Java:

Increased Complexity: Implementing the Business Delegate design pattern introduces additional complexity to the architecture. It requires the creation of additional components such as the delegate and service locator, which can increase the overall codebase size. Developers need to carefully manage the interaction between these components to ensure proper functioning and maintainability.
Potential Overhead: The abstraction provided by the Business Delegate pattern can introduce some overhead due to the additional layer of indirection. The delegate and service locator add an extra level of complexity and can impact performance. While the overhead might be negligible in most cases, it should be considered for performance-critical applications.
Learning Curve: Developers who are new to the Business Delegate design pattern may face a learning curve. Understanding the responsibilities and interactions of the delegate, service locator, and business services requires a solid grasp of the pattern’s concepts. Adequate training, documentation, and code examples can help overcome this challenge.
Increased Coupling with the Service Locator: The use of a service locator can introduce a level of coupling between the delegate and the locator. If the delegate relies heavily on the locator for service retrieval and initialization, changes in the locator’s implementation may impact the delegate. Careful design and adherence to principles like dependency inversion can mitigate this issue.

In the next article, I am going to discuss DAO Design Patterns in Java with Examples. Here, in this article, I try to explain Business Delegate Design Pattern in Java with Examples. I hope you understood the need for and use of the Business Delegate Design Pattern in Java.