Detailed explanation of examples of using websocket in php

What is WebSocket?

WebSocket is a persistent protocol, which is compared to http which is non-persistent. To give a simple example, the life cycle of http1.0 is defined by request, that is, a request and a response. For http, the session between the client and the server ends here; while in http1. 1, there is a slight improvement, that is, keep-alive is added, that is, multiple request requests and multiple response acceptance operations can be performed in one http connection. However, in real-time communication, it does not play a big role. HTTP requests can only be initiated by the client, and the server can return information. That is, the server cannot actively push information to the client and cannot meet the requirements of real-time communication. WebSocket can perform persistent connections, that is, the client only needs to perform a handshake, and data communication can continue after success. It is worth noting that WebSocket implements full-duplex communication between the client and the server, that is, the server can actively communicate when data is updated. Pushed to the client.

The following figure demonstrates the handshake part when establishing a websocket connection between client and server. This part can be completed very easily in node, because the net module provided by node has already done this for socket sockets. Without encapsulation processing, developers only need to consider the interaction of data when using it without having to deal with the establishment of connections.

The session content of the handshake between client and server when establishing a socket, that is, request and response

a. The information requested by the client from the server when establishing WebSocket

GET /chat HTTP/1.1
Host: server.example.com
Upgrade: websocket //告诉服务器现在发送的是WebSocket协议
Connection: Upgrade
Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw== //是一个Base64 encode的值，这个是浏览器随机生成的，用于验证服务器端返回数据是否是WebSocket助理
Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 13
Origin: php.cn

b. After the server obtains the information requested by the client, it processes the data according to the WebSocket protocol. And return, including encryption and other operations on Sec-WebSocket-Key

HTTP/1.1 101 Switching Protocols
Upgrade: websocket //依然是固定的，告诉客户端即将升级的是Websocket协议，而不是mozillasocket，lurnarsocket或者shitsocket
Connection: Upgrade
Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk= //这个则是经过服务器确认，并且加密过后的 Sec-WebSocket-Key,也就是client要求建立WebSocket验证的凭证
Sec-WebSocket-Protocol: chat

Explanation of the process of establishing socket in PHP

1. In PHP, socket communication is established between client and server. First, create a socket in PHP and listen for port information. The code is as follows:

<?php
//传相应的IP与端口进行创建socket操作
function WebSocket($address,$port){
$server = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_set_option($server, SOL_SOCKET, SO_REUSEADDR, 1);//1表示接受所有的数据包
socket_bind($server, $address, $port);
socket_listen($server);return $server;
}
?>

2. Design a loop to hang up the WebSocket channel to receive, process and send data

<?php
//对创建的socket循环进行监听，处理数据    
function run(){
  //死循环，直到socket断开
  while(true){
    $changes=$this->sockets;
    $write=NULL;
    $except=NULL;
    /*
    //这个函数是同时接受多个连接的关键，我的理解它是为了阻塞程序继续往下执行。
    socket_select ($sockets, $write = NULL, $except = NULL, NULL);
    $sockets可以理解为一个数组，这个数组中存放的是文件描述符。当它有变化（就是有新消息到或者有客户端连接/断开）时，socket_select函数才会返回，继续往下执行。 
    $write是监听是否有客户端写数据，传入NULL是不关心是否有写变化。 
    $except是$sockets里面要被排除的元素，传入NULL是”监听”全部。 
    最后一个参数是超时时间 
    如果为0：则立即结束 
    如果为n>1: 则最多在n秒后结束，如遇某一个连接有新动态，则提前返回 
    如果为null：如遇某一个连接有新动态，则返回
    */
    socket_select($changes,$write,$except,NULL);
    foreach($changes as $sock){
      //如果有新的client连接进来，则
      if($sock==$this->master){
        //接受一个socket连接
        $client=socket_accept($this->master);
        //给新连接进来的socket一个唯一的ID
        $key=uniqid();
        $this->sockets[]=$client;  //将新连接进来的socket存进连接池
        $this->users[$key]=array(
          &#39;socket&#39;=>$client,  //记录新连接进来client的socket信息
          &#39;shou&#39;=>false       //标志该socket资源没有完成握手
        );
        //否则1.为client断开socket连接，2.client发送信息
      }else{
        $len=0;
        $buffer=&#39;&#39;;
        //读取该socket的信息，注意：第二个参数是引用传参即接收数据，第三个参数是接收数据的长度
        do{
          $l=socket_recv($sock,$buf,1000,0);
          $len+=$l;
          $buffer.=$buf;
        }while($l==1000);
        //根据socket在user池里面查找相应的$k,即健ID
        $k=$this->search($sock);
        //如果接收的信息长度小于7，则该client的socket为断开连接
        if($len<7){
          //给该client的socket进行断开操作，并在$this->sockets和$this->users里面进行删除
          $this->send2($k);
          continue;
        }
        //判断该socket是否已经握手
        if(!$this->users[$k][&#39;shou&#39;]){
          //如果没有握手，则进行握手处理
          $this->woshou($k,$buffer);
        }else{
          //走到这里就是该client发送信息了，对接受到的信息进行uncode处理
          $buffer = $this->uncode($buffer,$k);
          if($buffer==false){
            continue;
          }
          //如果不为空，则进行消息推送操作
          $this->send($k,$buffer);
        }
      }
    }
  }
}
?>

3. After the above preliminary work of WebSocket is completed on the server side, wait for the client connection to proceed. It is very simple for the client to create a WebSocket. The code As follows:

var ws = new WebSocket("ws://IP:端口");
//握手监听函数
ws.onopen=function(){
  //状态为1证明握手成功，然后把client自定义的名字发送过去
  if(so.readyState==1){
    //握手成功后对服务器发送信息
    so.send('type=add&ming='+n);
  }
}
//错误返回信息函数
ws.onerror = function(){
  console.log("error");
};
//监听服务器端推送的消息
ws.onmessage = function (msg){
  console.log(msg);
}
//断开WebSocket连接
ws.onclose = function(){
  ws = false;
}

【Recommended tutorials】

1. "php.cn Dugu Jiujian (4)-php video tutorial"

2 . php programming from entry to master a complete set of tutorials

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