WebSocket subscriber using Stomp with Arduino

Projects Programming
1

I have created a simple Web socket application using Spring boot that's running on my local network on 192.168.1.50:8080(I've enabled CORS).

You can see the Spring boot application code here.

The server is waiting for a call from the URL /arduino/api/v1/getArduinoResponse and should forward the message to /arduino/subscribers channel.

The WebSocket server is fully functional.

@RestController

@MessageMapping("/arduino/api/v1")
@RequestMapping("/arduino/api/v1")
public class ArduinoControllerV1 {

    @Autowired
    private SimpMessagingTemplate template;

    @MessageMapping("/getArduinoResponse")
    @SendTo("/arduino/subscribers")
    public WebSocketResponseEntity getArduinoResponse(WebSocketResponseEntity message) throws Exception {
        return message;
    }


    @PostMapping("/sendCommand")
    public String sendCommand(@RequestBody CommandEntity commandEntity) throws Exception {
        this.template.convertAndSend("/arduino/subscribers", commandEntity.getCommand());
        return String.format("Sending to %s the command: %s ", commandEntity.getDeviceSerial(), commandEntity.getCommand());
    }
}

Configuration file:

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

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

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/arduino-websocket").setAllowedOriginPatterns("*").withSockJS();
    }

    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurerAdapter() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                registry.addMapping("/**").allowedOrigins("*");
            }
        };
    }

}

I have created a sketch on my Arduino MEGA that suppose to subscribe to the broker that belongs to the Spring boot server.

But for some reason, I'm receiving a message that I am unable to connect to the WS server. I know that I'm missing the channel name in the Arduino code, and I don't know where to put it.

This is my Arduino code:

#include <Arduino.h>
#include <WebSocketsClient.h>


#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };   //physical mac address
byte ip[] = { 192, 168, 1, 178 };                      // ip in lan (that's what you need to use in your browser. ("192.168.1.178")
byte gateway[] = { 192, 168, 1, 1 };                   // internet access via router
byte subnet[] = { 255, 255, 255, 0 };    

const char* ws_host               = "192.168.1.50";
const int   ws_port               = 8080;


const char* stompUrl              = "/arduino-websocket"; // don't forget the leading "/" !!!

WebSocketsClient webSocket;

void sendMessage(String & msg) {
    webSocket.sendTXT(msg.c_str(), msg.length() + 1);
}


void webSocketEvent(WStype_t type, uint8_t * payload, size_t length) {


    switch(type) {
        case WStype_DISCONNECTED:
            Serial.println("[WSc] Disconnected!\n");
            break;
        case WStype_CONNECTED:
            {
                Serial.print("[WSc] Connected to url: ");
                Serial.println((char *)payload);
                // send message to server when Connected
                webSocket.sendTXT("Connected");
            }
            break;
        case WStype_TEXT:
            Serial.print("[WSc] get text: ");
            Serial.println((char *)payload);
            // send message to server
            // webSocket.sendTXT("message here");
            break;
        case WStype_BIN:
            Serial.print("[WSc] get binary length: ");
            Serial.println(length);
           // hexdump(payload, length);

            // send data to server
            // webSocket.sendBIN(payload, length);
            break;
    }

}


void setup() {

    Serial.begin(115200);
    Serial.println("Started");
    while (!Serial) {
        ; // wait for serial port to connect.
    }
    Serial.println("Serial Started");

    // connect to Ethernet
    Ethernet.begin(mac, ip, gateway, subnet);
    while (!Ethernet.begin(mac)) {
       Serial.println("failed. Retrying in 5 seconds.");
       delay(5000);
       Serial.print("Starting W5100...");
     }
    Serial.println("Ethernet Started");
    Serial.print("I'm sitting on: ");
    Serial.println(Ethernet.localIP());

    

    // connect to websocket
    webSocket.begin(ws_host, ws_port, stompUrl);
    //webSocket.setExtraHeaders(); // remove "Origin: file://" header because it breaks the connection with Spring's default websocket config
    //    webSocket.setExtraHeaders("foo: I am so funny\r\nbar: not"); // some headers, in case you feel funny
    webSocket.onEvent(webSocketEvent);
}

void loop() {
    webSocket.loop();
}

Thanks for your help

2

Does that mean it redirects the client (302/303)? I doubt that an Arduino websocket library can handle redirects. Use the final URL for the websocket on the Arduino.

3

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