DWilliams

I'm developing an application that consists of several parts. The main website is written in PHP, but there are also several WebSocket servers that the user might need to connect to. The servers are written in C# and have no direct communication with the web server other than via sharing the same database. Where should I start reading to come up with a way to have website logins also authenticate the user on the WebSocket servers? Since the WebSocket connections are all done in client-side JS, nothing it does can be trusted. For example, if I have a WebSocket chat server, I don't want the connecting users to have to re-login but I also don't want to rely on the JavaScript to, for example, say "Hey, my name is Fred". I'd rather have the web server somehow tell the chat server "Yep, he's logged in as Fred, all is good".

Getting all users by a state or city is very easy. Assuming you have this data in a database then just query with " WHERE city='whatever' " or the same for state/country. Distance based calculations are a bit more complicated, though. First you'll need to get the latitude and longitude for each city. The Google Maps API could probably help you here. They have services where you can pass addresses in and get the latitude/longitude returned. Once you have that you can calculate the distance between two lat/long points with a bit of math. See http://www.movable-type.co.uk/scripts/latlong.html for details on how to do that (implementation is in JavaScript but it shouldn't be too hard to convert to PHP). Assuming you don't have thousands and thousands of users you could probably just loop through each user and calculate their distance from the city in question and kick them out of the result set if they are too far away

I don't know if this works on every platform, but in my particular Linux distro I just had to uncomment "extension=pdo_mysql.so" in php.ini

Sockets can operate in two different modes: 1) Blocking (default) 2) Non-blocking If in blocking mode, then yes, execution will stop until all the data is sent, and all your other clients will be left waiting. If in non-blocking mode, the function will send what it can then return. However, the OS does not keep the unsent data and slowly send it as it is able. This is something you have to manage yourself. socket_write returns the number of bytes successfully sent. If that is less than what you attempted to send, you need to store the excess bytes somewhere and try again later. Hmm, I'd previously been just calling socket_write and assuming magical network fairies took care of everything from that point on and carried my data from server to client. I'm a bit confused as to how TCP comes into effect here, though. I know that TCP is supposed to ensure that my packets arrive at their destination all intact and orderly, but if I send a chunk of data with socket_write over my TCP socket and it doesn't all get to the other side, isn't that contrary to TCP's guarantees or am I thinking about this on the wrong level? Given this knowledge, allow me to think out loud (and probably incorrectly) for how this should be done properly: I call socket_set_nonblock() on a user's socket as soon as they connect. Instead of having a send method that simply passes data on through socket_write, I should have it add data to a buffer. I should have some other code somewhere (where?) that routinely checks buffers and writes what it can, subtracting what went through until all data is sent. I don't know if I'm massively overthinking this of massively underthinking it I'm beginning to think all of this cannot be accomplished in a timely manner with only one thread?

A "simple" multiplayer game server using php/web sockets as the server and JS as the client. My 10MB example was a bit on the large side, nothing that large will likely ever be sent by the server, but still, if the server is locked while sending data then it will become locked up more the more users are connected, especially if their connections are bad. Might you have a link to something that explains how to better engineer a server?

First things first I'm terrible with JavaScript so I'm muddling through almost everything I do with it My basic goal here is that I need to "include" a list of JS files into my main file and pause execution of my main script until they're loaded. After some googling I've found jQuery's getScript() method. I tried to make a script loader function based on my (working) image preloader. Here's my code: function loadScripts(callback) { var scripts = new Array('cCell.js', 'cPlayer.js'); var loadedScripts = 0; var numScripts = scripts.length; for(var i = 0;i < numScripts;i++) { $.getScript(resPath + 'js/' + scripts[i], function() { if(++loadedScripts >= numScripts) callback(); }); } } resPath is defined outside that function but I have checked to verify the paths it creates is a valid path to my script. No matter what I try, the callback never seems to get called. At first I had resPath set to be a complete URL to my resource folder. I read somewhere that JS has security features to prevent executing code from a remote URL or something so I tried replacing it with both relative and absolute paths to no avail. What am I doing wrong?

Say I have a server written in PHP (don't ask ). Let's say I have 10 users connected to my script and one of those users, for the sake of the example, needs 10MB of data sent to them. If I send that data via socket_write(), does my program execution stop (therefor locking up every other user) until the data has gone through, or is the actual task of sending data over the tubes passed on to some lower level OS function so my program can get on with its flow?

Sure, here's the server code: http://pastebin.com/a1Mzt3pC Pretty much any simple websocket will work for it, here's the one I was using to test: http://code.google.com/p/phpwebsocket/source/browse/trunk/%20phpwebsocket/client.html I don't take credit for most of it, I mainly pieced it together from several outdated and/or half-working sources. My main contribution to it is the handshaking code. It has flaws obviously, the main being is that it isn't coded to properly respond to ping/pong/close packets but the framework is there and ready to be implemented. It's a good starting point for somebody wanting to implement a server, though. Also, for people not used to working with sockets in PHP take note that by default PHP has no support for listening sockets. In Linux/mac you'll need to recompile with --enable-sockets and under Windows you have to enable some module.

So it turns out the solution was much simpler than it seemed. The browser expects "\r\n\r\n" at the end of the handshake. Works fine with that, I now have a working websocket server

You don't grant permissions to PHP specifically, the webserver PHP is running under (most commonly Apache) is the process that needs to have write permissions to the upload folder. Apache is configurable to run as a specific user/group that changes based on the OS or distro so you'll need to look that up in the main httpd.conf file (assuming you're using Apache, if not refer to your webserver's documentation).

In that specific example you could do $car = substr('car/red/blue/gun/hit', 0, 3); http://php.net/manual/en/function.substr.php

I've implemented it with hybi-17 but it doesn't work. I don't see any differences in the handshake between what I implemented and the IETF paper for version 8. This is my handshake function: function dohandshake($user, $buffer) { server_log(1, 'Requesting handshake...'); // Determine which version of the WebSocket protocol the client is using if(preg_match("/Sec-WebSocket-Version: (.*)\r\n/ ", $buffer, $match)) $version = $match[1]; else return false; if($version == { // Extract header variables if(preg_match("/GET (.*) HTTP/" ,$buffer,$match)){ $r=$match[1]; } if(preg_match("/Host: (.*)\r\n/" ,$buffer,$match)){ $h=$match[1]; } if(preg_match("/Sec-WebSocket-Origin: (.*)\r\n/",$buffer,$match)){ $o=$match[1]; } if(preg_match("/Sec-WebSocket-Key: (.*)\r\n/",$buffer,$match)){ $k = $match[1]; } // Generate our Socket-Accept key based on the IETF specifications $accept_key = $k . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'; $accept_key = sha1($accept_key, true); $accept_key = base64_encode($accept_key); $upgrade = "HTTP/1.1 101 Switching Protocols\r\n" . "Upgrade: websocket\r\n" . "Connection: Upgrade\r\n" . "Sec-WebSocket-Accept: $accept_key"; socket_write($user->socket, $upgrade, strlen($upgrade)); $user->handshake = true; return true; } else { server_log("Client is trying to use an unsupported WebSocket protocol ({$version})"); return false; } } I can't tell for sure whether it's working but I suspect the handshake is not working.The JS client connects to it but when it tries to send data, I get a "Error: INVALID_STATE_ERR: DOM Exception 11" exception, and the readyState never changes from 0. When I feed the sample keys into my function it produces the correct accept key...

After some more tinkering I think I have confirmed that it is indeed the server script that's causing the problem. I don't see anything wrong with it but with new server code I was able to capture the packet. Now my problem is that the WebSocket protocol seems to be adapting so rapidly that trying to apply it seems like trying to hit a moving target. This is the packet I captured (sent from Chrome): GET / HTTP/1.1 Upgrade: websocket Connection: Upgrade Host: 192.168.1.29:12345 Sec-WebSocket-Origin: http://192.168.1.29 Sec-WebSocket-Key: 0fEMxyrlgsuDp8IA02nxCA== Sec-WebSocket-Version: 8 That differs from all the examples I can find on the internet as well as the Wikipedia page, so I guess I have to hunt down the IETF protocol description for version 8 and implement it off that...

Hmm I tried setting up the websocket example from this page and it doesn't work either. Similar result. No connection is made although the server script still shows something hitting it. No handshake packets are sent on this example either. Maybe something else is the issue here? I'm not running through a proxy or anything. I've tried it both from the local machine as well as from another computer and the result is the same EDIT: I've also tried in both Firefox 8 and Chrome 15

Yeah, the script outputs that it's being connected to: New client connected 0 Client disconnected 0 And I'm capturing loopback with wireshark. I can see all the packets for downloading the page itself, just nothing about websockets or the HTTP upgrade packet. I've looked through every HTTP packet it produces and run searches for any of the terms that should be in the handshake packet