将请求转发给 ws 客户端并等待响应 Express [英] Forward request to ws client and wait for response Express

问题描述

我正在尝试构建一个端点，该端点将接收请求，将请求数据发送到 WebSocket 客户端，等待事件，然后使用 express + socketio 发回响应.这个问题和它类似:Wait for socketio event inside express route

I'm trying to build an endpoint that will receive a request, emit the request data to a WebSocket client, wait for an event, then send back the response using express + socketio. This question is similar to it: Wait for socketio event inside express route

1) 在 http://localhost:3000/endpoint

2) 将事件作为 'req' 发送到网络套接字

2) Emit the event to web sockets as 'req'

3) 等待来自 ws 的 'res' 事件

3) Wait for 'res' event from ws

4) 发送接收到的事件详细信息作为 express 的响应.

4) Send the received events details as the response of express.

这是我的实现方式:

server.js

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);

app.get('/', (req, res) => {
    res.sendFile(__dirname + '/index.html');
});

var socket;

io.on('connection', function (s) {
    socket = s;
});

http.listen(3000);

app.get('/endpoint', function (req, res) {
    console.log('new request')
    io.emit('req', { data: 'hello' });
    socket.on('res', function (data) {
        res.status(200).json(data);
    });
});

index.html

<script src="/socket.io/socket.io.js"></script>
<script>
    var socket = io();
    socket.on('req', (data) => {
        console.log(data)
        socket.emit('res', data);
    });
</script>

该脚本对于 /endpoint 上的第一个请求工作正常.但是如果我再次点击网址，它会说

The script works fine for the first request on /endpoint. But if i hit the url again, it says

错误 [ERR_HTTP_HEADERS_SENT]:发送后无法设置标头给客户

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

推荐答案

请注意:

socket.on('res', function (data) {
    res.status(200).json(data);
});

每次套接字发送响应时都被调用，从而显示上述错误.您应该在回调函数内解除绑定侦听器.

Is being called each time a socket is sending a response, thus showing the above error. You should unbind the listener inside the callback function.

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