Events

我们 发布 了几个`ApplicationContext` 事件，并且可以通过实现 Spring 的 ApplicationListener 接口来接收它们：

Several ApplicationContext events are published and can be received by implementing Spring’s ApplicationListener interface:

  • BrokerAvailabilityEvent: Indicates when the broker becomes available or unavailable. While the “simple” broker becomes available immediately on startup and remains so while the application is running, the STOMP “broker relay” can lose its connection to the full featured broker (for example, if the broker is restarted). The broker relay has reconnect logic and re-establishes the “system” connection to the broker when it comes back. As a result, this event is published whenever the state changes from connected to disconnected and vice-versa. Components that use the SimpMessagingTemplate should subscribe to this event and avoid sending messages at times when the broker is not available. In any case, they should be prepared to handle MessageDeliveryException when sending a message.

  • SessionConnectEvent: Published when a new STOMP CONNECT is received to indicate the start of a new client session. The event contains the message that represents the connect, including the session ID, user information (if any), and any custom headers the client sent. This is useful for tracking client sessions. Components subscribed to this event can wrap the contained message with SimpMessageHeaderAccessor or StompMessageHeaderAccessor.

  • SessionConnectedEvent: Published shortly after a SessionConnectEvent when the broker has sent a STOMP CONNECTED frame in response to the CONNECT. At this point, the STOMP session can be considered fully established.

  • SessionSubscribeEvent: Published when a new STOMP SUBSCRIBE is received.

  • SessionUnsubscribeEvent: Published when a new STOMP UNSUBSCRIBE is received.

  • SessionDisconnectEvent: Published when a STOMP session ends. The DISCONNECT may have been sent from the client or it may be automatically generated when the WebSocket session is closed. In some cases, this event is published more than once per session. Components should be idempotent with regard to multiple disconnect events.

当您使用全功能中介时，STOMP “broker relay” 会在代理暂时不可用时自动重新连接 “system” 连接。但是，客户端连接不会自动重新连接。假设启用心跳，则客户端通常会注意到代理 10 秒内未响应。客户端需要实现自己的重新连接逻辑。

When you use a full-featured broker, the STOMP “broker relay” automatically reconnects the “system” connection if broker becomes temporarily unavailable. Client connections, however, are not automatically reconnected. Assuming heartbeats are enabled, the client typically notices the broker is not responding within 10 seconds. Clients need to implement their own reconnecting logic.