会话的详细接口，请参考：[《监听与会话》](/article/718)

### 1、单服务端时


```python
sessoin = await (SocketD.create_client("sd:ws://127.0.0.1:8602") 
                    .listen(EventListener().do_on("hello", lambda s, m: ...)) 
                    .open())
```

### 2、多服务端时，使用集群客户端


```python
sessoin = await (SocketD.create_cluster_client("sd:ws://127.0.0.1:8602", 
                            "sd:ws://127.0.0.1:8603", 
                            "sd:ws://127.0.0.1:8604") 
                    .listen(EventListener().do_on("hello", lambda s, m: ...)) 
                    .open())
```