# transport属性 ```要求（workerman >= 3.3.4）``` 设置传输属性，可选值为 [tcp](http://baike.baidu.com/subview/32754/8048820.htm) 和 [ssl](http://baike.baidu.com/view/525499.htm)，默认是tcp。 transport为 [ssl](http://baike.baidu.com/view/525499.htm) 时，要求PHP必须安装[openssl扩展](http://php.net/manual/zh/book.openssl.php)。 当把Workerman作为客户端向服务端发起ssl加密连接(https连接、wss连接等)时请设置此选项为```ssl```，例如下面的例子。 ### 示例 (https连接) ```php use \Workerman\Worker; use \Workerman\Connection\AsyncTcpConnection; require_once __DIR__ . '/Workerman/Autoloader.php'; $task = new Worker(); // 进程启动时异步建立一个到www.baidu.com连接对象，并发送数据获取数据 $task->onWorkerStart = function($task) { $connection_to_baidu = new AsyncTcpConnection('tcp://www.baidu.com:443'); // 设置为ssl加密连接 $connection_to_baidu->transport = 'ssl'; $connection_to_baidu->onConnect = function($connection_to_baidu) { echo "connect success\n"; $connection_to_baidu->send("GET / HTTP/1.1\r\nHost: www.baidu.com\r\nConnection: keep-alive\r\n\r\n"); }; $connection_to_baidu->onMessage = function($connection_to_baidu, $http_buffer) { echo $http_buffer; }; $connection_to_baidu->onClose = function($connection_to_baidu) { echo "connection closed\n"; }; $connection_to_baidu->onError = function($connection_to_baidu, $code, $msg) { echo "Error code:$code msg:$msg\n"; }; $connection_to_baidu->connect(); }; // 运行worker Worker::runAll(); ```