How to create a simple chat room using php websocket

socket is the intermediate software abstraction layer that communicates between the application layer and the TCP/IP protocol family. It is a set of interfaces. In the design mode, Socket is actually a facade mode, which hides the complex TCP/IP protocol family behind the Socket interface. For users, a set of simple interfaces is all, allowing Socket to organize data to meet the specified requirements. protocol. In the previous chapter, we talked about the difference between socket and http. To understand socket, you must first understand the difference between http and tcp. Simply put, one is a short chain, the other is a long chain, and the other is to pull data from the server. , one is that the server can actively push data. HTTP connections are divided into short connections and long connections. Short connections can generally be implemented using ajax, and long connections are websockets. Short connections are relatively simple to implement, but consume too many resources. Websocket is efficient but has some issues with compatibility. Websocket is a resource of html5.

php websocket creation simple chat room process introduction

php chat rooms used to be implemented through ajax and PHP. Today we Let’s take a look at a practical example of WebSocket technology in a PHP chat room.

1. Front-end client

How does the front-end file send information to the back-end server? Later research found that The WebSocket technology of js used, the following are common js WebSocket common operations:

The code is as follows:

var socket = new WebSocket('ws://localhost:8080');     
    // 打开Socket     
    socket.onopen = function(event) {     
    }    
    // 发送一个初始化消息    
     socket.send('I am the client and I\'m listening!');     
    // 监听消息    
     socket.onmessage = function(event) {     
        console.log('Client received a message',event);     
      };  //phpfensi.com    
    // 监听Socket的关闭    
      socket.onclose = function(event) {     
        console.log('Client notified socket has closed',event);     
      };     
      // 关闭Socket....     
    socket.close()     
   socket.onerror = function(evt){console.log(“WebSocketError!”);};

Description: The first line will send a handshake request to the specified server. If the server returns legal http header, the handshake is successful, and then the message sent by the server can be processed by listening to the onmessage event. There are many other events that can be monitored, see the previous URL.

2. Background server

The process of the server is roughly:

a. Suspend a socket process Waiting for connection

b. After there is a socket connection, traverse the socket array

c. If there is no handshake, perform handshake operation. If there is a handshake, receive the data, parse it and write it into the buffer for output

The sample code is as follows:

public function start_server(){
  $this->socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
  //允许使用本地地址
  socket_set_option($this->socket, SOL_SOCKET, SO_REUSEADDR, TRUE);
  socket_bind($this->socket, $this->host, $this->port);
  //最多10个人连接，超过的客户端连接会返回WSAECONNREFUSED错误
  socket_listen($this->socket, $this->maxuser);
  while(TRUE) {
    $this->cycle = $this->accept;
    $this->cycle[] = $this->socket;
    //阻塞用，有新连接时才会结束
    socket_select($this->cycle, $write, $except, null);
    foreach ($this->cycle as $k => $v) {
      if($v === $this->socket) {
        if (($accept = socket_accept($v)) < 0) {
          continue;
        }
        //如果请求来自监听端口那个套接字，则创建一个新的套接字用于通信
        $this->add_accept($accept);
        continue;
      }
      $index = array_search($v, $this->accept);
      if ($index === NULL) {
        continue;
      }
      //没消息的socket就跳过
      if (!@socket_recv($v, $data, 1024, 0) || !$data) {
        $this->close($v);
        continue;
      }
      if (!$this->isHand[$index]) {
        $this->upgrade($v, $data, $index);
        if(!empty($this->function['add'])) {
          call_user_func_array($this->function['add'], array($this));
        }
        continue;
      }
      $data = $this->decode($data);
      if(!empty($this->function['send'])) {
        call_user_func_array($this->function['send'], array($data, $index, $this));
      }
    }
    sleep(1);
  }
}
//增加一个初次连接的用户
public function add_accept($accept){
  $this->accept[] = $accept;
  $index = array_keys($this->accept);
  $index = end($index);
  $this->isHand[$index] = FALSE;
}
//关闭一个连接
public function close($accept) {
  $index = array_search($accept, $this->accept);
  socket_close($accept);
  unset($this->accept[$index]);
  unset($this->isHand[$index]);
  if(!empty($this->function['close'])) {
    call_user_func_array($this->function['close'], array($this));
  }
}
//响应升级协议
public function upgrade($accept, $data, $index) {
  if (preg_match("/Sec-WebSocket-Key: (.*)\r\n/",$data,$match)) {
    $key = base64_encode(sha1($match[1] . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11', true));
    $upgrade  = "HTTP/1.1 101 Switching Protocol\r\n" .
      "Upgrade: websocket\r\n" .
      "Connection: Upgrade\r\n" .
      "Sec-WebSocket-Accept: " . $key . "\r\n\r\n";  //必须以两个回车结尾
    socket_write($accept, $upgrade, strlen($upgrade));
    $this->isHand[$index] = TRUE;
  }
}

Explanation: There are several key points. One is while(true) to suspend the process, otherwise the process will exit after executing it once. The second is the use of socket_select and socket_accept functions. The third is the handshake when the client makes the first request.

The following process is very clear. When a new client request arrives, use socket_accept to create a resource and add it to the $this->accept connection pool. And set its label isHand to false, then the next time it cycles (because $this->cycle[] = $this->socket;$this->cycle has changed, so socket_select will return) Perform upgrade handshake. Then just wait for its new messages.

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