javascript 如何在javascript中实现webSocket连接的Ping/Pong请求？
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How to implement Ping/Pong request for webSocket connection alive in javascript?
提问by Qwer Sense
I use websocket in javascript. But the connection close after one minute.
我在 javascript 中使用 websocket。但是连接在一分钟后关闭。
I am wondering somethings:
我想知道一些事情：
1- Is not Websocket naturaly providing with Ping/Pong messages not to close the connection? I think it have to. Otherwise what is the difference between websocket and TCP connection?
1- 不是 Websocket 自然地提供 Ping/Pong 消息来不关闭连接吗？我认为它必须。否则 websocket 和 TCP 连接有什么区别？
2- If I have to send the ping/pong messages, how is the ping message sent? What am I need to do? Is WebSocket object provide a ping method? Or should I call a method as websocket.send("ping") ? I am use naturaly WebSocket object in javascipt.
2- 如果我必须发送 ping/pong 消息，ping 消息是如何发送的？我需要做什么？WebSocket 对象是否提供 ping 方法？或者我应该调用一个方法作为 websocket.send("ping") ？我在 javascipt 中使用自然的 WebSocket 对象。
3- Should the server respond to Ping requests with Pong? Should this be implemented separately on the server side?
3- 服务器是否应该使用 Pong 响应 Ping 请求？这应该在服务器端单独实现吗？
Note:Sorry for my english.
注意：对不起我的英语。
采纳答案by ouni
At this point in time, heartbeats are normally implemented on the server side: there's not much you can do from the client end.
此时，心跳通常是在服务器端实现的：从客户端您无能为力。
However, if the server keeps killing your socket connection, and you have no control over it, it is possible for the client to send arbitrary data to the websocket on an interval:
但是，如果服务器不断终止您的套接字连接，而您无法控制它，则客户端可能会按时间间隔向 websocket 发送任意数据：
let socket = null;
function connect_socket() {
socket = new WebSocket(ws_url);
socket.on("close", connect_socket); // <- rise from your grave!
heartbeat();
}
function heartbeat() {
if (!socket) return;
if (socket.readyState !== 1) return;
socket.send("heartbeat");
setTimeout(heartbeat, 500);
}
connect_socket();
I strongly recommend trying to sort out what's happening on the server end, rather than trying to work around it on the client.
我强烈建议尝试理清服务器端发生的事情，而不是尝试在客户端上解决它。
回答by ouni
Yes, there are ping/pong frames in websockets. Here is an example using the wsmodule, where the server is initiating the ping request:
是的，websockets 中有 ping/pong 帧。这是使用该ws模块的示例，其中服务器正在启动 ping 请求：
const http = require('http');
const ws = require('ws');
const server = http.createServer(function(req_stream_in, res_stream_out) {
// handle regular HTTP requests here
});
const webSocketServer = new ws.Server({
path: "/websocket",
server: server
});
const connected_clients = new Map();
webSocketServer.on('connection', function connection(ws_client_stream) {
// NOTE: only for demonstration, will cause collisions. Use a UUID or some other identifier that's actually unique.
const this_stream_id = Array.from(connected_clients.values()).length;
// Keep track of the stream, so that we can send all of them messages.
connected_clients.set(this_stream_id, ws_client_stream);
// Attach event handler to mark this client as alive when pinged.
ws_client_stream.is_alive = true;
ws_client_stream.on('pong', () => { ws_client_stream.is_alive = true; });
// When the stream is closed, clean up the stream reference.
ws_client_stream.on('close', function() {
connected_clients.delete(this_stream_id);
});
});
setInterval(function ping() {
Array.from(connected_clients.values()).forEach(function each(client_stream) {
if (!client_stream.is_alive) { client_stream.terminate(); return; }
client_stream.is_alive = false;
client_stream.ping();
});
}, 1000);
回答by Pim Heijden
Mozilla documents a dedicated convention for ping/pong.
Mozilla 记录了一个专门的 ping/pong 约定。
At any point after the handshake, either the client or the server can choose to send a ping to the other party. When the ping is received, the recipient must send back a pong as soon as possible. You can use this to make sure that the client is still connected, for example.
A ping or pong is just a regular frame, but it's a control frame. Pings have an opcode of 0x9, and pongs have an opcode of 0xA. When you get a ping, send back a pong with the exact same Payload Data as the ping (for pings and pongs, the max payload length is 125). You might also get a pong without ever sending a ping; ignore this if it happens.
If you have gotten more than one ping before you get the chance to send a pong, you only send one pong.
在握手之后的任何时候，客户端或服务器都可以选择向对方发送 ping。当收到 ping 时，接收者必须尽快发回一个 pong。例如，您可以使用它来确保客户端仍处于连接状态。
ping 或 pong 只是一个常规框架，但它是一个控制框架。Ping 的操作码为 0x9，pong 的操作码为 0xA。当您收到 ping 时，发送回具有与 ping 完全相同的有效负载数据的 pong（对于 ping 和 pong，最大有效负载长度为 125）。你也可能在不发送 ping 的情况下得到一个 pong；如果发生，请忽略它。
如果在有机会发送 pong 之前您已经收到了多个 ping，则您只发送了一个 pong。
请参阅：https: //developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers#Pings_and_Pongs_The_Heartbeat_of_WebSockets
Find more in depth discussion about ping/pong from the browser side here: Sending websocket ping/pong frame from browser
从浏览器端找到更多关于 ping/pong 的深入讨论：Sending websocket ping/pong frame from browser
More specifically, read the Websocket RFC 6455about ping/pong.
更具体地说，请阅读有关 ping/pong的 Websocket RFC 6455。
回答by upteryx
In ouni's solution, heartbeat() wasn't kicking in. It works when it's put in an openevent like this:
在 ouni 的解决方案中， heartbeat() 没有启动。当它被放入这样的open事件中时它会起作用：
let socket = null;
function connect_socket() {
socket = new WebSocket(ws_url);
socket.on("close", connect_socket); // <- rise from your grave!
socket.on("open", heartbeat); // heartbeat when the socket is open
}
function heartbeat() {
if (!socket) return;
if (socket.readyState !== 1) return;
socket.send("heartbeat");
setTimeout(heartbeat, 500);
}
connect_socket();
