Socket.IO cannot establish a connection

[marmon179]

I use socket.io-client for Javascript(4.5.0) server on JAVA and when I enter address 'ws://10.201.223.67:9902/' the request is not by 'ws' but by 'http'.

It returns

Although I understand it should just come back 0

It keeps trying to connect.

[darrachequesne]

Which server implementation are you using? Could you please check if it's implementing the latest Socket.IO protocol?

See also: https://socket.io/docs/v4/troubleshooting-connection-issues/#problem-the-socket-is-not-able-to-connect

[marmon179]

Hello.client socket.io (2.4.0 JavaScript), I want to connect to the Socket.IO JAVA server (2.x.x).When I set transports: ['websocket', 'polling']. The request doesn't go at all.When I request through Postman the connection is established.

My code

  `    export function useSocketIO(url: string) {
        const ioRef = useRef<Socket>();
      const [connected, setConnected] = useState(false);

    useEffect(() => {
     ioRef.current = io(url, {
    transports: ['websocket', 'polling'],
    });
     ioRef.current.on('connect', () => {
      console.log('WS Connected to', url);
       setConnected(() => true);
     });

ioRef.current.on('disconnect', () => {
  console.log('WS disconnected');
  setConnected(() => false);
});

       return () => {
       console.log('WS destroyed');
         ioRef.current?.close();
       };
       }, [url]);

       return {
        io: ioRef.current,
       connected,
      };
     }

       export type RealtimeOptions<T> = {
       event: string;
       onEvent?: (data: T) => void;
      };

       export type CollectionService<T> = {
       options: RealtimeOptions<T>;
      events: Array<T>;
      send: (data: T) => void;
      emit: (event: string, data: T) => void;
     };

   
     const DEFAULT_URL = 'ws://10.201.223.67:9902/';

   export function useRealtime<T>(options: RealtimeOptions<T>): CollectionService<T> {
    const [url] = useState(DEFAULT_URL);
    const { io } = useSocketIO(url);
    const [events, setEvents] = useState<Array<T>>([]);

      useEffect(() => {
       io?.on(options.event, (data: T) => {
        setEvents((events) => {
         return [...events, data];
        });
       options.onEvent?.(data);
       });
      }, [io, options, events, options.event]);

     return {
      options,
      events,
       send: (data) => io?.send(data),
     emit: (event, data) => io?.emit(event, data),
     };
 }`