```mermaid
sequenceDiagram
    participant Device
    participant Broker
    participant Web
    Device->>Broker: 建立TCP连接
    Broker->>Broker: 5s未注册，主动断开
    Device->>Broker: 注册报文
    Broker->>Device: 注册回复
    Device->>Broker: 心跳报文
    Broker->>Device: 心跳报文
    Web->>Broker: 创建Session
    Broker->>Device: 创建Session

```