Event-driven Programming

Event-driven

Programming

(and Websockets!)

in PHP

Event-driven Sockets

• Most of ReactPHP depends on an event-driven socket library
• Callbacks occur whenever data is received on the socket
• When the callback is complete, control returns to the event loop
• This is the architecture used by highly scalable web servers like Nginx

About Me

ReactPHP Libraries

Websockets

Simple HTTP Web Server

Simple ZeroMQ Server

• What are websockets?

• How are they implemented?

• What browsers support websockets?

• Predis/Async – Redis client
• DNode-PHP – Node.js-compatible RPC bindings
• Ratchet – Websockets and other servers
• React/ZMQ – ZeroMQ messaging protocol
• React/Stomp – Stomp messaging protocol
• React/Promise – CommonJS Promises/A for PHP
• React/Partial – Pre-fill function arguments

$loop = React\EventLoop\Factory::create();

$socket = new React\Socket\Server($loop);

$http = new React\Http\Server($socket);

$http->on('request', function ($request, $response) {

$response->writeHead(200, [ 'Content-Type' => 'text/plain' ]);

$response->end("Hello World!\n");

});

$socket->listen(8080);

$loop->run();

$loop = React\EventLoop\Factory::create();

$context = new React\ZMQ\Context($loop);

$pull = $context->getSocket(ZMQ::SOCKET_PULL);

$pull->bind('tcp://127.0.0.1:5555');

$pull->on('message', function ($msg) {

printf("RECV: %s\n", $msg);

});

$loop->run();

Websockets - JavaScript

Websockets - PHP

$app = new Ratchet\App("chat.local", 8080);

$app->route("/chat", new Demo\Chat());

$app->run();

var conn = new WebSocket('ws://chat.local:8080/chat');

conn.onmessage = function(e) {

$(“#output”).prepend($(“<div />”).html(e.data);

}

function send_message(msg) {

conn.send(msg);

}

Demo\Chat needs to implement Ratchet's MessageComponentInterface

• onOpen
• onClose
• onError
• onMessage

• 15 years experience in web development and administration (systems, databases, networks)
• Various jobs: Web Developer, Chief Architect, Manager of IT, Director of Technical Operations, Database Consultant
• Mostly worked with MySQL, as a developer, DBA, and administrator
• Member of the Utah Open Source Foundation (UTOS) core team
• Help organize the OpenWest Conference
• Organizer of the Ski PHP Conference

Partial Functions

Promises API

• Implements the CommonJS Promises/A standard
• Allows you to defer giving an answer while allowing other processing to continue
• A “Promise” is a value returned as a placeholder for the final result
• To use a promise, pass a function to the then() method of the Promise object

Demo Code

• Pre-fill function arguments, return new function
• Use Partial\...() or Partial\placeholder() to skip arguments

use React\Partial;

$square = Partial\bind(“pow”, Partial\…(), 2);

$four = $square(2);

$nine = $square(3);

$sixteen = $square(4);

Promises API - Example

$wisdom = new Wisdom\Wisdom($whois_client);

foreach ($domains as $domain) {

$wisdom->check($domain)->then(

function ($avail) use ($domain) {

$txt = $avail ? “unused” : “taken”;

echo “Domain $domain is $txt.\n”;

}

);

}

$loop->run();

https://github.com/stevecoug/reactphp-whois

https://github.com/stevecoug/reactphp-demo

composer.json

bin/chat.php

app/Demo/Http.php

onOpen

app/Demo/Chat.php

History of ReactPHP

require_once __DIR__."/../vendor/autoload.php";

$ip = (isset($argv[1])) ? $argv[1] : "127.0.0.1";

$hostname = (isset($argv[2])) ? $argv[2] : "localhost";

$loop = React\EventLoop\Factory::create();

$http_socket = new React\Socket\Server($loop);

$http = new React\Http\Server($http_socket);

$http->on('request', [ new Demo\Http(), "onRequest" ]);

$http_socket->listen(8000, $ip);

$app = new Ratchet\App($hostname, 8080, $ip, $loop);

$app->route("/chat", new Demo\Chat());

$app->run();

{

"autoload": {

"psr-0": {

"Demo": "app"

}

},

"require": {

"php": ">5.4",

"cboden/Ratchet": "0.3.*",

"react/zmq": "0.2.*",

"react/partial": "~2.0",

"react/http": "*"

}

}

namespace Demo;

define("HTDOCS", realpath(__DIR__."/../../htdocs"));

class Http {

public function onRequest($request, $response) {

$path = $request->getPath();

$file = realpath(HTDOCS.$path);

if ($path === "/") return $this->redirect($response, "/chat.html");

if (substr($file, 0, strlen(HTDOCS)) !== HTDOCS || !is_file($file)) return $this->error404($response);

$ext = pathinfo($file, PATHINFO_EXTENSION);

switch ($ext) {

case "js": $type = "application/javascript"; break;

case "html": $type = "text/html"; break;

default: $type = "text/plain"; break;

}

echo "HTTP FILE: $path ($type)\n";

$response->writeHead(200, [ 'Content-Type' => $type ]);

$response->end(file_get_contents(HTDOCS.$path));

}

}

namespace Demo;

use Ratchet\MessageComponentInterface;

use Ratchet\ConnectionInterface;

class Chat implements MessageComponentInterface {

protected $clients;

protected $next_conn_id = 1;

public function __construct() {

$this->clients = new \SplObjectStorage;

}

public function onOpen(ConnectionInterface $conn) {

$conn_id = $this->next_conn_id++;

$name = "Connection #$conn_id";

$auth = false;

$color = "000000";

$info = [

"id" => $conn_id,

"conn" => $conn,

"auth" => $auth,

"name" => $name,

"color" => $color,

];

$this->clients->attach($conn, $info);

if ($name = $conn->WebSocket->request->getCookie("demo_chat_name")) {

$color = $conn->WebSocket->request->getCookie("demo_chat_color");

try {

$this->setupAuth($conn, $name, $color, $info);

} catch (\Exception $e) {

echo "WS Invalid cookie auth received ($conn_id)\n";

}

}

}

SplObjectStorage

Standard PHP Library

Store objects, and

associated data

onClose, onError

onMessage

setupAuth

recvMessage

validateName, validateColor

private function setupAuth($conn, $name, $color, $info) {

if ($info === null) $info = $this->clients->offsetGet($conn);

$this->validateName($name);

$this->validateColor($color);

$conn->send(json_encode([

"type" => "auth",

"valid" => true,

"name" => $name,

"color" => $color,

]));

$info['auth'] = true;

$info['name'] = $name;

$info['color'] = $color;

$this->clients->offsetSet($conn, $info);

}

public function onClose(ConnectionInterface $conn) {

$info = $this->clients->offsetGet($conn);

$this->clients->detach($conn);

printf("WS DISCONNECTED: %s\n", $info['name']);

}

public function onError(ConnectionInterface $conn, \Exception $e) {

$conn->close();

}

private function recvMessage($from_conn, $data, $info) {

if ($info['auth'] === true) {

foreach ($this->clients as $client) {

if ($client !== $from_conn) {

$client->send(json_encode([

"type" => "chat",

"from" => $info['name'],

"color" => $info['color'],

"message" => $data->message,

]));

}

}

}

}

private function validateName($name) {

if (strlen($name) < 3) {

throw new \Exception("Display name ($name) must be at least 3 characters long");

}

if (strlen($name) > 20) {

throw new \Exception("Display name ($name) cannot exceed 20 characters long");

}

if (!preg_match('/^[A-Za-z]([A-Za-z0-9]+[ ._-])*[A-Za-z0-9]+$/', $name)) {

throw new \Exception("Display name ($name) contains illegal characters");

}

}

private function validateColor($color) {

if (!preg_match('/^[0-9a-fA-F]{6}$/', $color)) {

throw new \Exception("Invalid color selected: $color");

}

}

public function onMessage(ConnectionInterface $from_conn, $payload) {

try {

$data = json_decode($payload);

$info = $this->clients->offsetGet($from_conn);

switch ($data->type) {

case "chat":

$this->recvMessage($from_conn, $data, $info);

break;

case "auth":

$this->setupAuth($from_conn, $data->name, substr($data->color, 1), $info);

break;

default:

print_r($data);

$this->sendError($from_conn, "Unknown message type received: $data->type");

break;

}

} catch (\Exception $e) {

$this->sendError($from_conn, $e->getMessage());

}

}

• Ratchet began as a socket abstraction in 2011 by Chris Boden
• In April 2012, worked with Igor Wiedler to create an evented API for sockets
• Core contributors also include Daniele Alessandri, Jan Sorgalla, Christian Lück, and Jeremy Mikola
• The library uses the Reactor pattern, which is where the name came from

Thank you for coming!

@stevecoug

http://github.com/stevecoug

http://joind.in/10872