HTML5_07之WebSocket

1、HTML5新特性之WebSocket：
 ①HTTP协议的不足：基于“请求——响应”模型，只有在客户端发送请求后，服务器才会给予响应；对于实时的股票走势图，以及聊天通讯等无法满足需求；
 ②解决方案：setInterval+AJAX：心跳请求；
  问题：过于频繁对服务器压力过大，频率过低则信息获取延迟；
 ③最佳解决方案——WebSocket协议：
  基于“广播——收听”模型，客户端连接到服务器后不再断开，服务器有了消息随时发送给客户端，客户端也可以不停地给服务器发送消息；
  不足：客户端和服务器是永久连接，服务器端可容纳的连接数是有限的；
 ④WebSocket应用需要服务器端和客户端都使用WebSocket协议；
 ⑤socket_server.php：

<?php

$address = "127.0.0.1";

$port = 9999; //调试的时候，可以多换端口来测试程序！

set_time_limit(0);

$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);

socket_set_block($sock);

socket_bind($sock, $address, $port);

socket_listen($sock, 4);

do

{

echo "Waiting for Connection...\n";

$msgsock = socket_accept($sock);

echo "Waiting for Request...\n";

$buf = socket_read($msgsock, 8192);     //读取请求

echo "Request Received: $buf\n";

$response = hand_shake($buf);

socket_write($msgsock,$response,strlen($response)); //发送响应

//正式开始通信...

$buf = socket_read($msgsock, 8192);

for($i=0; $i<5; $i++){

$msg = "WELCOME $i\n";

$msg = code($msg);

sleep(1);

socket_write($msgsock, $msg, strlen($msg));

}

socket_close($msgsock);

} while (true);

socket_close($sock);

function hand_shake($buf){

$buf  = substr($buf,strpos($buf,'Sec-WebSocket-Key:')+18);

$key  = trim(substr($buf,0,strpos($buf,"\r\n")));

$new_key = base64_encode(sha1($key."258EAFA5-E914-47DA-95CA-C5AB0DC85B11",true));

$new_message = "HTTP/1.1 101 Switching Protocols\r\n";

$new_message .= "Upgrade: websocket\r\n";

$new_message .= "Sec-WebSocket-Version: 13\r\n";

$new_message .= "Connection: Upgrade\r\n";

$new_message .= "Sec-WebSocket-Accept: " . $new_key . "\r\n\r\n";

return $new_message;

}

function code($msg){

$msg = preg_replace(array('/\r$/','/\n$/','/\r\n$/',), '', $msg);

$frame = array();

$frame[0] = '81';

$len = strlen($msg);

$frame[1] = $len<16?'0'.dechex($len):dechex($len);

$frame[2] = ord_hex($msg);

$data = implode('',$frame);

return pack("H*", $data);

}

function ord_hex($data)  {

$msg = '';

$l = strlen($data);

for ($i= 0; $i<$l; $i++) {

$msg .= dechex(ord($data{$i}));

}

return $msg;

}