Kafka\Protocol\Encoder::_encodeMessage PHP Method

    protected static function _encodeMessage($message, $compression = self::COMPRESSION_NONE)
    {
        // int8 -- magic  int8 -- attribute
        $data = self::pack(self::BIT_B8, self::MESSAGE_MAGIC);
        $data .= self::pack(self::BIT_B8, $compression);
        // message key
        $data .= self::encodeString('', self::PACK_INT32);
        // message value
        $data .= self::encodeString($message, self::PACK_INT32, $compression);
        $crc = crc32($data);
        // int32 -- crc code  string data
        $message = self::pack(self::BIT_B32, $crc) . $data;
        return $message;
    }

 /**
  * encodeMessage
  *
  * @access public
  * @return void
  */
 public static function encodeMessage($message, $compression = self::COMPRESSION_NONE)
 {
     return parent::_encodeMessage($message, $compression);
 }