多次发送回复？

Question

I have a little problem.

I have a node application on a server, that serves a website as control panel for a client based application.

Example:

1. You click a link on the site
2. A http request triggers the server to send a command via socket to the client
3. The client executes this command
4. The client sends the output of the command back to the server (socket)

That works fine, on time. The second time the server crashes because the header is already sent.

//Comand comes in
app.get('/create/:id/:package', function (req, res) {
    if (io.sockets.connected[req.params.id]) {
        //Command is sent to client
        io.sockets.connected[req.params.id].emit('control', {type: 'create', packageName: req.params.package});
        //Output is coming back
        socket.on('createOutput', function (data) {
            //Response sent back to http request (works once)
            res.send(data);
        });
    }
});

Is there any way to work around this behavior?

Answer 1

You can send the data only once with socket.once :

socket.once('createOutput', function (data) {
        //Response sent back to http request (works once)
        res.send(data);
    })