WebSockets implementation

This documentation outlines how WebSocket communication is used to manage project notifications in the application in the Back-end side.

Front-end websockets implementation

Dependency Setup

Add the required WebSocket dependency in your build.gradle file:

implementation 'org.springframework.boot:spring-boot-starter-websocket'

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Configuration

Create a WebSocket configuration file to define the topics and endpoints for your WebSocket connections. Below is an example configuration:

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        // Enable a simple message broker for topic destinations
        config.enableSimpleBroker("/projectws");
        // Define a user destination prefix
        config.setUserDestinationPrefix("/projectws");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        // Register the WebSocket endpoint and allow cross-origin requests
        registry.addEndpoint("/ws").setAllowedOrigins("http://localhost:3000");
    }
}

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Controller for Notifications

To enable the backend to send notifications through WebSockets, a controller can be created. Below is an example implementation:

@RestController
@AllArgsConstructor
@RequestMapping("notifications")
public class NotificationsController {

    private final SimpMessagingTemplate messagingTemplate;

    @PostMapping
    public ResponseEntity<Void> sendNotificationToUsers(@RequestBody NotificationMessage message) {
        // Publish the message to the "/project/payment" topic
        messagingTemplate.convertAndSend("/project/payment", message);
        return ResponseEntity.status(HttpStatus.CREATED).build();
    }
}

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Key Components Explained

1. WebSocket Configuration:

   • configureMessageBroker: Configures the message broker to handle destinations prefixed with /projectws.
   • registerStompEndpoints: Defines /ws as the endpoint for WebSocket connections and allows cross-origin requests from http://localhost:3000.

2. SimpMessagingTemplate:

   • Used to send messages to WebSocket destinations.
   • In the example above, messages are sent to the /project/payment topic.

3. REST Endpoint for Notifications:

   • The sendNotificationToUsers method accepts NotificationMessage payloads via a POST request and broadcasts them to the topic /project/payment.