Swoole 网络通信协议，固定包头。

网络通信过程中，可能会出现分包和合包的情况。具体情况如https://wiki.swoole.com/wiki/page/484.html文档所讲的。这里测试了下固定包头的协议。示例代码如下

1.解包封装的方法 

communicationPack.php

<?php
//对数据信息封装
function packData($sendData,$packModel){
    return pack($packModel, strlen($sendData)).$sendData;
}

//解包
function unpackData($rcvData,$packModel){
    $length = $packModel=='N'?4:2;
    return substr($rcvData,$length);
}

2.服务端 tcpServer.php

<?php
require_once 'communicationPack.php';
$packModel = 'N';
//创建Server对象，监听 127.0.0.1:9501端口
$serv = new swoole_server("127.0.0.1", 9501);
$serv->set(array(
    'open_length_check' => true,
    'package_max_length' => 2000000,
    'package_length_type' => $packModel, //see php pack()
    'package_length_offset' => 0,
    'package_body_offset' => $packModel=='N'?4:2,
));
//监听连接进入事件
$serv->on('connect', function ($serv, $fd) {
    echo "Client: Connect.
";
});

//监听数据接收事件
$serv->on('receive', function ($serv, $fd, $from_id, $data) use($packModel){
    echo "#{$serv->worker_id}>> received length=" . strlen($data) ."data=".$data. "}
";
    $data = unpackData($data,$packModel);
    $returnStr = "Server: ".$data;
    $serv->send($fd, packData($returnStr,$packModel));
});

//监听连接关闭事件
$serv->on('close', function ($serv, $fd) {
    echo "Client: Close.
";
});

//启动服务器
$serv->start();

启动服务端

3 客户端 tcpClient.php

<?php
require_once 'communicationPack.php';
$packModel = 'N';
$client = new swoole_client(SWOOLE_SOCK_TCP);
$client->set(array(
    'open_length_check'     => true,
    'package_length_type'   => $packModel,
    'package_length_offset' => 0,       //第N个字节是包长度的值
    'package_body_offset'   => $packModel=='N'?4:2,       //第几个字节开始计算长度
    'package_max_length'    => 2000000,  //协议最大长度
));
//连接到服务器
if (!$client->connect('127.0.0.1', 9501, 0.5))
{
    die("connect failed.");
}
//向服务器发送数据
//数据协议
$sendData = "test123";
$sendData = packData($sendData,$packModel);
if (!$client->send($sendData))
{
    die("send failed.");
}
//从服务器接收数据
$data = $client->recv();
if (!$data)
{

    die("recv failed.");
}
echo unpackData($data,$packModel);
//关闭连接
$client->close();

 然后启动客户端

服务端会打印

pack N是将数据转成了无符号32位的数字，这个刚好长度是4个字节，所以设定

package_body_offset=4