Transfer Object Design Pattern in Java

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

What is Transfer Object Design Pattern?

In software development, the Transfer Object Design Pattern provides an efficient and flexible way to transfer data between components or layers of an application. It encapsulates a set of related data fields into a single object, which can be easily serialized, transmitted, and reconstructed at the receiving end.

The Transfer Object design pattern aims to improve the performance and maintainability of data transfer operations by encapsulating related data fields into a single object. It is often used in scenarios where data needs to be transferred between remote components or layers of an application.

Components of Transfer Object Design Pattern

The Transfer Object Design Pattern consists of the following components:

Transfer Object: It is a lightweight, serializable object that encapsulates a set of related data fields. The Transfer Object typically consists of public properties or getter/setter methods to access and manipulate the data. It does not contain any business logic.
Client: The client component represents the consumer or recipient of the data. It interacts with the Transfer Object to retrieve or update the data fields it requires.

Example to Understand Transfer Object Design Pattern in Java

To illustrate the Transfer Object design pattern in a real-world context, let’s consider an application that handles employee data. The application needs to transfer employee information between the client-side and server-side components efficiently. The Transfer Object pattern can be employed to encapsulate the employee data into a single object for transmission.

In this example, the employee Transfer Object serves as a container for the employee’s personal details such as name and id. The Transfer Object includes getter and setter methods to access and manipulate the employee data fields.

When an employee updates their information, the client-side component gathers the necessary data and creates an employee Transfer Object. The object is then transmitted to the server-side component, which receives the Transfer Object and extracts the relevant data fields to update the employee’s profile or perform other operations.

By using the Transfer Object pattern, the application benefits from reduced network traffic and improved performance. Instead of transmitting each customer data field individually, the entire set of data is encapsulated within a single Transfer Object, minimizing network overhead. This approach is particularly useful in scenarios where multiple employee data fields need to be transferred between the client and server.

Furthermore, the Transfer Object promotes code maintainability by centralizing the definition and management of the employee data structure. If additional data fields are required in the future or changes are made to the existing fields, the modifications can be implemented within the Transfer Object without affecting the client and server components separately. The UML Diagram of this example is given below using Transfer Object Design Pattern.

Implementing Transfer Object 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 transferobjet.

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

public class Employee
{
    private int id;
    private String name;

    public Employee(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Employee [id=" + id + ", name=" + name + "]";
    }
}

This is the POJO class that needs to be encapsulated and transferred.

Step 4: In the project, create a new file called EmployeeManager.java. This class is responsible for managing the employees as well as operations performed on employees (such as adding, updating, and deleting). Add the following code to EmployeeManager.java:

import java.util.ArrayList;
import java.util.List;

public class EmployeeManager
{
    private List<Employee> employees;
    
    public EmployeeManager ()
    {
        employees = new ArrayList<>();
        employees.add(new Employee(0, "Employee A"));
        employees.add(new Employee(1, "Employee B"));
        employees.add(new Employee(2, "Employee C"));
    }

    public void delete(Employee e)
    {
        employees.remove(e.getId());
        System.out.println("Employee #" + e.getId() + " deleted!");
    }

    public List<Employee> getAllEmployees()
    {return employees;}

    public Employee getEmployee(int id)
    {return employees.get(id);}

    public void update(Employee e)
    {
        employees.get(e.getId()).setName(e.getName());
        System.out.println("Employee #" + e.getId() + " updated!");
    }
}

Step 5: In the project, create a new file called TransferObjectPatternDemo.java. This class will contain the main() function. Add the following code to TransferObjectPatternDemo.java:

public class TrasferObjectPatternDemo
{
    public static void main(String[] args)
    {
        EmployeeManager em = new EmployeeManager();

        System.out.println("Employees before update:");
        for (Employee e : em.getAllEmployees())
            System.out.println(e.toString());

        em.update(new Employee(2, "Employee X"));

        System.out.println("Employees after update:");
        for (Employee e : em.getAllEmployees())
            System.out.println(e.toString());
    }    
}

The main() function does the following things, in order

Prints out the list of all the employees
Modifies the name of one employee
Reprints the list of employees to demonstrate that the update was successful

Step 6: Compile and execute the application. Ensure compilation is successful. Verify that the program works as expected.

Congratulations! You now know how to implement Transfer Object Design Pattern in Java!

UML Diagram of Transfer Object Design Pattern:

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

The classes can be described as follows:

Object: This is the object that needs to be encapsulated and transferred.
ObjectManager: This class is responsible for the communication between DriverClass and Objects.
DriverClass: This class contains the main() function and is responsible for the simulation of the program.

Advantages of Transfer Object Design Pattern in Java:

The followings are the advantages of using the Transfer Object Design Pattern in Java:

Performance Improvement: The Transfer Object pattern helps improve performance by reducing the number of remote calls or data transfers. Instead of transferring individual data fields or making multiple requests, the Transfer Object encapsulates all required data into a single object, minimizing network overhead and latency.
Reduced Network Traffic: By bundling related data fields into a Transfer Object, the pattern reduces network traffic. Instead of transferring multiple data packets or messages, the Transfer Object allows for efficient serialization and deserialization of the entire object, resulting in fewer network round trips.
Encapsulation of Data: The Transfer Object pattern encapsulates related data fields into a single object, providing a structured way to transmit and access data. It promotes data integrity and reduces the risk of data inconsistencies during transfer, as all relevant fields are contained within a cohesive object.
Improved Maintainability: The Transfer Object pattern enhances code maintainability by centralizing the definition and management of data structures. Changes to the data fields or structure can be easily made within the Transfer Object, and all clients automatically benefit from these modifications without requiring individual code updates.
Separation of Concerns: The Transfer Object pattern separates the data transfer concerns from the business logic. It allows developers to focus on the implementation of business rules and algorithms separately from the data transmission and serialization concerns, promoting code organization and reusability.

Disadvantages of Transfer Object Design Pattern in Java:

The followings are the disadvantages of using the Transfer Object Design Pattern in Java:

Increased Object Size: The Transfer Object pattern can lead to increased object sizes, especially when large amounts of data are bundled within a single object. This can impact memory usage and network bandwidth, particularly in scenarios where only a subset of the data fields is required by the client. Care should be taken to balance the benefits of data encapsulation with the potential overhead of larger objects.
Tight Coupling: In some cases, the Transfer Object pattern can result in tight coupling between the client and the Transfer Object. If the Transfer Object’s structure or data fields change, all clients using the Transfer Object need to be updated accordingly. This can introduce dependencies and maintenance challenges, particularly in large-scale applications with numerous clients.
Limited Flexibility: The Transfer Object pattern may lack flexibility in scenarios where data transformation or additional processing is required before transferring the data. Since the Transfer Object only encapsulates data fields without containing business logic, additional transformations or manipulations may need to be performed outside the Transfer Object, leading to code duplication or added complexity.
Potential Over-serialization: The Transfer Object pattern can result in over-serialization, where unnecessary data fields are included in the Transfer Object. This can impact performance and network bandwidth if irrelevant or sensitive data is transmitted over the network. It’s essential to carefully consider the fields included in the Transfer Object to avoid unnecessary data transfer.

Real-Time Use Cases of Transfer Object Design Pattern in Java

The Transfer Object pattern finds practical applications in various software development scenarios:

Remote Method Invocations: In distributed systems or remote procedure call (RPC) scenarios, the Transfer Object pattern is used to transfer data between client and server components. It allows for efficient serialization and deserialization of data, reducing network traffic and improving performance.
Web Services: When exposing data through web services, the Transfer Object pattern is commonly used to represent the data being transferred between the service provider and the service consumer. The Transfer Object encapsulates the relevant data fields and can be easily serialized into different formats such as JSON or XML for efficient transmission.
Data Access Layers: In applications with a separate data access layer, the Transfer Object pattern is used to encapsulate data retrieved from the database or other data sources. It allows for the efficient transfer of data between the data access layer and the business logic layer, reducing the number of database queries and improving overall performance.
Distributed Caching: When caching data in distributed systems, the Transfer Object pattern can be used to transfer the cached data between different nodes or layers of the cache infrastructure. It enables efficient serialization and deserialization of the cached data, reducing the need for repetitive network calls.

In the next article, I am going to discuss Intercepting Filter Design Pattern in Java with Examples. Here, in this article, I try to explain Transfer Object Design Pattern in Java with Examples. I hope you understood the need for and use of the Transfer Object Design Pattern in Java.