Class not found error

I'm trying to execute function in PMMP plugin file from other PHP file.
But, Class not found error is outputted at other PHP file.

Code is
PMMP plugin

PHP:

<?php
namespace EasyCHAT;

use pocketmine\Player;
use pocketmine\plugin\PluginBase;
use pocketmine\Server;
use pocketmine\event\Listener;
use pocketmine\event\player\PlayerChatEvent;
use pocketmine\utils\Config;
use EasyCHAT\WebSocket;

class EasyCHAT extends PluginBase implements Listener{

static $Instance;

public function onLoad(){
 $instance = $this;
}

public static function getInstance(){
 return self::$Instance;
}

public function onEnable(){
  if(!file_exists($this->getDataFolder())){
    mkdir($this->getDataFolder(), 0744, true);
    $this->config = new Config($this->getDataFolder()."Data.json", Config::JSON);
    $this->config->set("ID", "");
    $this->config->save();
  }
    $this->config = new Config($this->getDataFolder()."Data.json", Config::JSON);
    $this->getServer()->getPluginManager()->registerEvents($this, $this);
    $this->getLogger()->info("ロード完了");
}

public function onChat(PlayerChatEvent $event){
  $Message = $event->getMessage();
  $PlayerName = $event->getPlayer()->getName();
  $this->getLogger()->info($Message."+".$PlayerName);
}

public static function showMessage($mes){
    $this->getLogger()->info("メッセージを受信しました: ".$mes);
}
}

other PHP file

PHP:

<?php
namespace EasyCHAT;

use Ratchet\MessageComponentInterface;
use Ratchet\ConnectionInterface;
use Ratchet\Server\IoServer;
use Ratchet\WebSocket\WsServer;
use Ratchet\Http\HttpServer;
use EasyCHAT\EasyCHAT;
require __DIR__.'/vendor/autoload.php';

class WebSocket implements MessageComponentInterface {
protected $clients;
  public function __construct() {
    $this->clients = new \SplObjectStorage;
  }

  public function onOpen(ConnectionInterface $conn) {
    $this->clients->attach($conn);
  }

  public function onMessage(ConnectionInterface $from, $msg) {
    foreach ($this->clients as $client) {
      if ($from != $client) {
        $client->send($msg);
      }
    }
    echo $msg;

    $send = EasyCHAT::getInstance();
    $send->showMessage($msg);
  }

  public function onClose(ConnectionInterface $conn) {
    $this->clients->detach($conn);
  }

  public function onError(ConnectionInterface $conn, \Exception $e) {
    $conn->close();
  }
}

$server = IoServer::

I want to execute "showMessage" function in PMMP plugin file.
But, when the "onMessage" function of other PHP file is executed, that error is output to the command prompt executing other PHP file.

What should I do?

 

Which class name?

 

You just initialized $config twice...

 

In other words, do you mean you can not run a class if composer is used?

 

Sorry. It is my mistake.

 

Before that, even if I didn't composer, a similar error was output.