Using web sockets in your PHP application. Jeff Kolesnikowicz

Transcription

1 Using web sockets in your PHP application Jeff Kolesnikowicz

2 My mom told me to start with a joke Fwd: FW: Fw: Fwd: Fwd: Computer Cartoons

3 About me Building websites since 1999, working with PHP since 2001 Office manager (cat) doesn t get enough scratches

4 What are web sockets? Part of HTML5 Full-duplex client/server communication For real time communication between client and server accessible from nonbrowser applications Built into (most) browsers.

5 Source:

6 Web sockets VS AJAX Web sockets are full-duplex Client-server relationship Connection is persistent and stateful Authentication is built-in to AJAX

7 WAMP No, not the stack Web Application Messaging Protocol Facilitates two types of messaging patterns: publish and subscribe (pub/sub) and, remote procedural call (RPC)

8 WAMP Pub/Sub A client subscribes to a topic and receives all messages in the topic Not limited to 1:1 communication. Scales from 0 to N clients Client cannot request information outside of what is pushed Can be used as a chat, updating configuration between services

9 WAMP RPC Can call custom functions 1:1 communication with the server Can be used to request data, direct communication between browsers, games Server can make a request of the browser and vice versa

10 Ratchet PHP implementation of WAMP protocol Provides server side hooks for pub/sub as well as RPC Provides a flash based client side polyfill Provides a read-only Symfony session handler And more! Canadian!

11 The new shiny Ratchet does not support WAMP2 Thruway does ( github.com/voryx/thruway)

12 WAMP Server Server: <?php use Ratchet\Server\IoServer; use Ratchet\Http\HttpServer; use Ratchet\WebSocket\WsServer; use Ratchet\Wamp\WampServer; use Ratchet\Cookbook\OpenPubSub; require dirname( DIR ). '/vendor/autoload.php'; use MyApp\WampDemo; $server = IoServer::factory( new HttpServer( new WsServer( new WampServer( new WampDemo ) ) ), 8080 ); $server->run();

13 class WampDemo implements WampServerInterface { protected $clients; public function construct() { } $this->clients = new \SplObjectStorage; public function oncall(connectioninterface $conn, $id, $topic, array $params) { } echo "Calling $topic"; public function onsubscribe(connectioninterface $conn, $topic) { echo "Subscribing to $topic"; } public function onunsubscribe(connectioninterface $conn, $topic) { echo "Unsubscribing to $topic"; } public function onpublish(connectioninterface $conn, $topic, $event, array $exclude, array $eligible) { echo "Publishing to $topic"; } public function onopen(connectioninterface $conn) { $this->clients->attach($conn); echo "Connected\n"; } public function onclose(connectioninterface $conn) { $this->clients->detach($conn); } echo "Closed\n"; public function onerror(connectioninterface $conn, \Exception $e) { echo "An error has occurred: {$e->getmessage()}\n"; } $conn->close(); }

14 Client side <script> var connection = new autobahn.connection({ url: ws:// :8080, realm: "demo" }); connection.onopen = function (session, details) { }; console.log("connection established!", session, details); session.call( test"); session.subscribe("test.topic"); session.publish("test.topic"); connection.onclose = function (reason, details) { } console.log("connection lost: " + reason); connection.onmessage = function(e) { }; console.log(e.data); connection.open(); </script>

15 Demo

16 How we used web sockets The problem Application built by external vendor each AJAX request very slow ms+ Data integrity was poor: APP.Case.Score = 100; Duplication of functionality between client and server side Game was attached to a large legacy application

17 How we used web sockets What we needed to do Move logic somewhere that can t be accessed by a user Speed application up Needs to be extensible Could not be entirely rewritten The business wants it done yesterday

18 How we used web sockets The solution Web sockets are faster than AJAX Web sockets are persistent Scoring logic now server side Game is now event driven Lost data is less likely

19 How we used websockets The application

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21 Not so fast aka These are the pitfalls I ve known PHP is not great at running 24/7 Crashy McCrashface Firewalls & Proxies

22 Caching Crashes Get our hands dirty with core dumps Crashing when calling redit_sock_write Connection to caching server was getting disconnected

23 ulimit gotta be kidding me PHP Fatal error: Uncaught exception... Too many open files Everything in UNIX is a file - including sockets PHP has a default limit of 1024 open files jeff@devlocal:~$ ulimit -n 65535

24 ulimit gotta be kidding me OS gave PHP a file handle that was higher than expected, so crashed A theoretical limit of 1024 connections per server (probably lower) lower number of open files Create new user and edit /etc/ security/limits.conf websocket-user hard nofile 1024 websocket-user soft nofile 1024

25 Problem by proxy More restrictive firewalls may need to whitelist web socket servers Useful for diagnosis: Match protocol of webpage and web socket (IE) Run wss to pass through proxy servers Many firewalls block ports above 1024

26 Balancing daemons Use upstart to run web socket server Restart daily Build in a reconnect to help automatically reconnect users

27 A balancing act Rackspace load balancers don t support web sockets Amazon s ELB does (with some work) HAProxy does Apache and Nginx support load balancing and routing through a URL

28 Nginx We load balance through Nginx (will switch to HAProxy) Able to redirect web sockets to a URL Routed through port 443 Websocket server (port 8000) Nginx /websocket/ (port 80) Websocket server (port 8000) Websocket server (port 8000)

29 Nginx configuration http { map $http_upgrade $connection_upgrade { default upgrade; '' close; } upstream websocket { least_conn; server :8000; server :8000; server :8000; } server { listen 8000; location /websocket/ { proxy_pass proxy_http_version 1.1; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection $connection_upgrade; }

30 Monitoring Load balancing helps, but requires a number of failures before down Adding a new piece of infrastructure - monitor it! Pingdom don t support web socket monitoring Newrelic supports process monitoring

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32 Monitoring { public function pingservers() { $reports = []; foreach ($this->servers as $server) try { $report = $this- >pingserver($server, $this->port, $this- >path); $server]; } catch (Exception $e) { $report = "$server is down"; $value = ['server' => AppStat::increment('webapp.server.down', $value); } } } $reports[$server] = $report; return $reports; private function pingserver($server, $port, $path) { $loop = React\EventLoop\Factory::create(); App::import('Lib', 'Simucase.Client'); $client = new Client($loop, $server, $port, $path); $response = null; $params = [json_encode([])]; $client->setonwelcomecallback(function (Client $conn, $data) use (&$response, $loop, $params) { $conn->call('helloworld', $params, function ($data) use (&$response, $loop, $conn) { $response = $data; $loop->stop(); }); }); } $loop->run(); return $response;

33 Provide users with feedback

34 Build a compatibility page for users

35 In Summary Faster and more robust than AJAX Think long and hard before using PHP Adding a piece of fussy infrastructure Know your audience Inform your audience

36 Thank you! Questions? Slides available at Please rate my talk: Sample code available at I m on jeff@codepoets.ca