Websocket does not connect even in LAN after some failures

user_881712 0
Viewed 29

Here my websocket.js code:

let ws = null;
let connected = false;

const TIMER_RECONNECTION = 10000;
const TIMER_TIMEOUT = 8000;

setInterval(reconnect, TIMER_RECONNECTION);

const extractHostname = function (url) {
    let hostname;
    if (url.indexOf("://") > -1) hostname = url.split("/")[2];
    else hostname = url.split("/")[0];
    hostname = hostname.split(":")[0];
    hostname = hostname.split("?")[0];
    return hostname;
};

const composeWsAddress = function (address) {
    let scheme = "ws";
    if (document.location.protocol === "https:") scheme += "s";
    return scheme + "://" + address + ":8000/ws";
};

const open = function (address) {
    console.log("Connecting...");

    delete ws;
    ws = new WebSocket(address);
    ws.onopen = onOpen;
    ws.onclose = onClose;
    ws.onmessage = onMessage;

    setTimeout(() => {
        if (ws && ws.readyState === WebSocket.CONNECTING) {
            ws.close();
            connected = false;
            console.log("aborted!");
            return;
        }
    }, TIMER_TIMEOUT);
};

let onOpen = function() {
    console.log("success!");
    connected = true;
};

let onClose = function() {
    ws = null;
    connected = false;
};

let onMessage = function(event) {
};

WebSocketClient = {
    init: function() { }
};

function reconnect() {
    if (connected === false) {
        const address = composeWsAddress(extractHostname(location.href));
        open(address);
    }
}

$(function() {
    WebSocketClient.init();
    reconnect();
});

The expected behavior is:

  1. try to connect to the websocket server
  2. if the connection is not done within 8 seconds, abort it
  3. every 10 seconds check the connection state: if not connected retry

It works quite well:

Connecting...
aborted!      [after 8 seconds]
Connecting... [after 2 more seconds]
aborted!      [after 8 seconds]
Connecting... [after 2 more seconds]
aborted!      [after 8 seconds]
success!

If it fails for a quite long time, not sure how much, say several minutes, then when the server it's available it continues to fail again for minutes before connecting. Reloading the page does not help.

The only way I found to connect immediately (after this situation) is to close and open again the whole browser (Firefox).

But I cannot ask the user to do this! How to improve my code to avoid such a behavior?

websocket javascript
1 Answers

I would suggest a simpler mechanism for reconnecting that uses the onError event:

const open = function (address) {
    console.log("Connecting...");

    if(ws && ws.readyState !== WebSocket.CLOSED) ws.close();
    ws = new WebSocket(address);
    ws.onopen = onOpen;
    ws.onclose = onClose;
    ws.onmessage = onMessage;
    ws.onerror = onError;
};

let onError = function() {
    console.log("connection failed, reconnecting ...");
    setTimeout(reconnect, 1000);
};

I.e., no timed abortion and let the websocket do the timing. The onError event will tell you when it is time to do another reconnect try.

Whether this solves your problem needs some testing in your environment. Maybe the timed abortion and too early reconnect creates the problem.

user_86721770
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