This is probably a simple mistake. I have a nodejs Server running socket.io, I have got everything to work within the server.

However, I want to be able to make a CURL post via PHP to the node server, and have it emit the data. I can make the server receive the request, but when I try to emit the data, I get an error saying that the socket is not defined.

This is obvious in my code. My question is, how do I require socket.io before I setup the server? Hopefully a segment my code will help explain my problem:

var http = require('http')
, url = require('url')
, fs = require('fs')
, server;

server = http.createServer(function(req, res) {
// your normal server code
var path = url.parse(req.url).pathname;
switch (path){
   case '/':
     res.writeHead(200, {'Content-Type': 'text/html'});
     res.write('
Hello! Enter
');
     res.end();
     break;
   case '/index.html':
     fs.readFile(__dirname + path, function(err, data){
        if (err) return send404(res);
        res.writeHead(200, {'Content-Type': path == 'json.js' ? 'text/javascript' : 'text/html'})
        res.write(data, 'utf8');
        res.end();
     });
    break;
   case '/write.html':
     fs.readFile(__dirname + path, function(err, data){
        if (err) return send404(res);
        res.write(data, 'utf8');
        res.end();
     });
   break;
  case '/post':
     console.log(req.toString());
     socket.broadcast.emit('user', {state: 'PHP Post', userid: 'PHP'});
     res.writeHead(200);
     res.end();
   break;

  default: send404(res);
}
}),

send404 = function(res){
   res.writeHead(404);
   res.write('404');
   res.end();
};

server.listen(843);

// socket.io 
var io = require('socket.io').listen(server);

// Regular socket.io events

how do I require socket.io before I setup the server?

That part is pretty easy; at the top of your file, do something like:

var http = require('http')
, url = require('url')
, fs = require('fs')
, socketIO = require('socket.io')  // 

and at the bottom:

var io = socketIO.listen(server);

The problem is, in your POST handler, you're using socket.broadcast.emit, but socket isn't defined. Are you trying to send a message to all Socket.IO users? If so, you can use io.sockets.emit; I'd probably do something like this:

var http = require('http')
, url = require('url')
, fs = require('fs')
, server
, io;

...

case '/post':
   console.log(req.toString());
   io.sockets.emit('user', {state: 'PHP Post', userid: 'PHP'});
   res.writeHead(200);
   res.end();
 break;

...

io = require('socket.io').listen(server);

If you're trying to send data to a single socket, or every socket except for a particular one (which is how you'd normally use socket.broadcast), you'll somehow need to map HTTP requests to Socket.IO sockets; using sessions for this is common.