Spring: send message to websocket clients

Question

I'm building a webchat with Spring Boot, RabbitMQ and WebSocket as POC, but I'm stucked a the last point: WebSockets
I want my ws clients to connect to a specific endpoint, like /room/{id} and when a new message arrives, I want the server to send the response to clients, but I searched for something similar and didn't found.

Currently, when the message arrives, I process it with RabbitMQ, like

container.setMessageListener(new MessageListenerAdapter(){
            @Override
            public void onMessage(org.springframework.amqp.core.Message message, Channel channel) throws Exception {
                log.info(message);
                log.info("Got: "+ new String(message.getBody()));
            }
        });

what I would like is, instead log it , I want to send it to the client, for example: websocketManager.sendMessage(new String(message.getBody()))

Luiz E. · Accepted Answer · 2015-11-30 09:59:57Z

10

Ok, I think I got it, for everyone who needs it, here is the answer:

first, you need to add WS dependencies to the pom.xml

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-messaging</artifactId>
</dependency>

create a WS endpoint

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        // the endpoint for websocket connections
        registry.addEndpoint("/stomp").withSockJS();
    }

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/");

        // use the /app prefix for others
        config.setApplicationDestinationPrefixes("/app");
    }

}

Note: I'm using STOMP, so the clients should connect like this

<script type="text/javascript">
    $(document).ready(function() {
        var messageList = $("#messages");
        // defined a connection to a new socket endpoint
        var socket = new SockJS('/stomp');
        var stompClient = Stomp.over(socket);
        stompClient.connect({ }, function(frame) {
            // subscribe to the /topic/message endpoint
            stompClient.subscribe("/room.2", function(data) {
                var message = data.body;
                messageList.append("<li>" + message + "</li>");
            });

        });
    });
</script>

Then, you can simply wire the ws messenger on your components with

@Autowired
private SimpMessagingTemplate webSocket;

and send the message with

webSocket.convertAndSend(channel, new String(message.getBody()));

answered Nov 30, 2015 at 9:59

Luiz E.

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2 Comments

Key Lay Over a year ago

where did "channel" come from as your destination argument to convertAndSend?

Luiz E. Over a year ago

channel is a string. it is the "room" I'm sending the message, something like "/room.".concat(message.getRoom().getUid().toString())

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