Building a Real-Time Bidding System for Car Booking with Spring Boot, WebSocket, and ActiveMQ
Tags: bidding, webdev, springboot, java
Published: 2023-10-28 03:09:30


In the fast-paced world of online services, having a real-time bidding system for car booking can be a game-changer. In this technical blog, we'll guide you through the process of building a robust and efficient bidding system using Spring Boot and WebSocket while leveraging ActiveMQ to protect against concurrent transactions. With this technology stack, you can create a dynamic platform that facilitates car bookings with seamless, real-time auction-style bidding.

![Bidding Car System](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/pnqnycc1lubojik5hixn.png)

## 1. **Why Real-Time Bidding Matters**

Real-time bidding systems have gained popularity across various industries, from online advertising to e-commerce. They enable instant transactions and engagement, which are crucial for services like car booking. Here are some key reasons why a real-time bidding system is essential:

- **Dynamic Pricing**: Real-time bidding allows for dynamic pricing, ensuring that customers are charged a fair market rate at any given time.
- **Instant Booking**: Customers can quickly secure a car by placing bids in real-time, eliminating the need for manual reservations and confirmations.
- **Competitive Advantage**: A bidding system can set you apart from competitors by providing a unique, interactive experience for users.
- **Efficient Allocation**: It enables efficient allocation of available cars, ensuring that resources are used optimally.

## 2. **Building a Real-Time Bidding System with Spring Boot and WebSocket**

### 2.1. Setting Up the Development Environment

Before diving into the coding, make sure you have the following tools and libraries installed:

- Java Development Kit (JDK)
- Apache Maven
- Spring Boot
- WebSocket
- ActiveMQ

### 2.2. Designing the Bidding System

In a real-time bidding system, you need components for users to place bids, see the current highest bid, and automatically allocate the car to the highest bidder. Here's a simplified structure:

- **WebSocket Server**: Handles real-time communication between the server and clients. Spring Boot makes it easy to set up WebSocket support.
- **Bidding Engine**: Manages the bidding process, including validating and recording bids, determining the highest bid, and awarding the car to the highest bidder.
- **ActiveMQ**: ActiveMQ acts as a message broker to ensure that concurrent transactions are processed securely. It prevents race conditions and data inconsistency.

### 2.3 Building the Spring Boot Application

Create a Spring Boot project and set up your WebSocket server. You can use Spring's built-in WebSocket support to establish real-time communication between clients and the server. This is where users can place their bids and see updates in real-time.

### 2.4. Implementing the Bidding Engine

The bidding engine is responsible for processing bids and determining the highest bidder. You'll need to write code to:

- Accept bid requests from clients.
- Validate bids to ensure they meet certain criteria (e.g., minimum bid increments).
- Keep track of the current highest bid.
- Notify clients of changes in the highest bid.

**Let's start with the setup…**

**WebSocket Configuration in Spring Boot**

Here's how you can set up WebSocket configuration in Spring Boot:

```java
@Configuration
@EnableWebSocket
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic"); // Enable topic-based messaging
        config.setApplicationDestinationPrefixes("/app"); // Set application prefix for client messages
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/ws-bidding").withSockJS(); // WebSocket endpoint for clients
    }
}
```

**Bidding Engine: Processing Bids**

```java
@RestController
@RequestMapping("/bidding")
public class BiddingController {

    private double currentHighestBid = 0.0;
    private String currentHighestBidder = null;

    @MessageMapping("/placeBid/{bookingId}")
    @SendTo("/topic/bidding/{bookingId}")
    public BidResponse placeBid(@Payload BidRequest bidRequest, @DestinationVariable String bookingId) {
        double newBid = bidRequest.getBidAmount();

        if (newBid > currentHighestBid) {
            currentHighestBid = newBid;
            currentHighestBidder = bidRequest.getUsername();
        }

        return new BidResponse(currentHighestBid, currentHighestBidder);
    }
}
```

**ActiveMQ Integration: Handling Concurrent Transactions**

Here's an example of setting up ActiveMQ to handle concurrent transactions:

```java
@Configuration
@EnableJms
public class ActiveMQConfig {

    @Bean
    public JmsListenerContainerFactory<?> myFactory(ConnectionFactory connectionFactory,
            DefaultJmsListenerContainerFactoryConfigurer configurer) {
        DefaultJmsListenerContainerFactory factory = new DefaultJmsListenerContainerFactory();
        configurer.configure(factory, connectionFactory);
        return factory;
    }

    @JmsListener(destination = "biddingQueue")
    public void processBid(String message) {
        // Process the bid in a thread-safe manner
        // You can implement your logic here to handle concurrent transactions
    }
}
```

These are simplified code examples to get you started. In a real-world application, you would need to consider user authentication, data validation, and more complex business logic. Additionally, you would likely have a more extensive system with multiple components, such as user management, car inventory, and auction end conditions.

### 2.6. Testing and Scaling

Once your bidding system is set up, thoroughly test it to ensure it's functioning as expected. Pay special attention to the real-time aspect, ensuring that bids are processed promptly and that clients receive updates in real-time. As your platform grows, you can scale your infrastructure to handle increased traffic and bidding activity.

## **Conclusion**

Building a real-time bidding system for car booking with Spring Boot, WebSocket, and ActiveMQ is a powerful way to enhance your car rental service. It enables dynamic pricing, instant bookings, and a competitive edge in the market. By combining these technologies, you can provide a seamless, interactive experience for your users while safeguarding against concurrent transactions with ActiveMQ. With this system in place, you'll be well on your way to transforming the car booking industry.

This technical blog serves as a roadmap to get you started on building your real-time bidding system, and it's a promising step towards creating a more dynamic and engaging platform for your users. Happy coding!