延迟入站适配器和控制总线

Question

我的集成流程代码是：

@Bean
    public IntegrationFlow messageFlow() {
        return IntegrationFlows.from(stompInboundChannelAdapter())
                .transform(inBoundStompMsgTransformer::transform)
                .headerFilter("stomp_subscription","content-length")
                .handle(Amqp.outboundAdapter(outboundConfiguration.rabbitTemplate()))
                .get();
    }

我正在使用 Spring 启动。

清除日志指出 {transformer} 订阅者已添加到输入频道

2019-12-09 18:21:41.752  INFO 18248 --- [           main] o.s.i.s.i.StompInboundChannelAdapter     : started bean 'stompInboundChannelAdapter'; defined in: 'class path resource [com/mahesh/siuspdemo/adapter/InBoundStompAdapter.class]'; from source: 'org.springframework.core.type.classreading.SimpleMethodMetadata@21e360a'
2019-12-09 18:21:41.768  INFO 18248 --- [           main] o.s.i.endpoint.EventDrivenConsumer       : Adding {transformer} as a subscriber to the 'stompInputChannel' channel
2019-12-09 18:21:41.768  INFO 18248 --- [           main] o.s.integration.channel.DirectChannel    : Channel 'application.stompInputChannel' has 1 subscriber(s).
2019-12-09 18:21:41.768  INFO 18248 --- [           main] o.s.i.endpoint.EventDrivenConsumer       : started bean 'inboundFlow.org.springframework.integration.config.ConsumerEndpointFactoryBean#0'; defined in: 'class path resource [com/mahesh/siuspdemo/adapter/InBoundStompAdapter.class]'; from source: 'bean method inboundFlow'
2019-12-09 18:21:41.768  INFO 18248 --- [           main] o.s.i.endpoint.EventDrivenConsumer       : Adding {header-filter} as a subscriber to the 'inboundFlow.channel#0' channel
2019-12-09 18:21:41.772  INFO 18248 --- [           main] o.s.integration.channel.DirectChannel    : Channel 'application.inboundFlow.channel#0' has 1 subscriber(s).
2019-12-09 18:21:41.772  INFO 18248 --- [           main] o.s.i.endpoint.EventDrivenConsumer       : started bean 'inboundFlow.org.springframework.integration.config.ConsumerEndpointFactoryBean#1'; defined in: 'class path resource [com/mahesh/siuspdemo/adapter/InBoundStompAdapter.class]'; from source: 'bean method inboundFlow'
2019-12-09 18:21:41.772  INFO 18248 --- [           main] o.s.i.endpoint.EventDrivenConsumer       : Adding {amqp:outbound-channel-adapter} as a subscriber to the 'inboundFlow.channel#1' channel
2019-12-09 18:21:41.772  INFO 18248 --- [           main] o.s.integration.channel.DirectChannel    : Channel 'application.inboundFlow.channel#1' has 1 subscriber(s).
2019-12-09 18:21:41.772  INFO 18248 --- [           main] o.s.i.endpoint.EventDrivenConsumer       : started bean 'inboundFlow.org.springframework.integration.config.ConsumerEndpointFactoryBean#2'; defined in: 'class path resource [com/mahesh/siuspdemo/adapter/InBoundStompAdapter.class]'; from source: 'bean method inboundFlow'

但是，我得到一个异常，我丢失了队列中的第一个 one/two 消息。它处理剩余的消息。

假设在启动应用程序之前队列中有 10 条消息。启动应用程序后，即使日志显示订阅者已添加且 bean 已启动，我仍收到异常，post 异常，处理了 8/9 条消息。

例外情况是：org.springframework.messaging.MessageDeliveryException: Dispatcher has no subscribers for channel 'application.stompInputChannel'.; nested exception is org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers, failedMessage=GenericMessage

很明显，上下文还没有完全准备好处理消息，因此出现了异常。 但日志消息具有误导性。

我的第一个问题：

那么添加订阅者并启动 bean 到底意味着什么？这是否意味着一切都已设置，但上下文仍必须准备好处理消息？

为了克服这个问题，正如许多 post 中所建议的那样，我使用控制总线来启动适配器。代码是：

......
@Component
public class ApplicationLifeCycle implements SmartLifecycle {

    @Autowired
    private MessageChannel controlBusChannel;

    @Override
    public void start() {
        System.out.println("Service starting...");
        controlBusChannel.send(new GenericMessage<>("@stompInboundChannelAdapter.start()"));
    }
.....

我创建了 public class ApplicationLifeCycle implements SmartLifecycle 认为它会很方便。

我的第二个问题是：

这是使用控制总线处理 start/stop 适配器的 right/best 方式吗？如果方法不对，请告诉我正确的方法。

谢谢，

马赫什

Answer 1

我认为这是你另一个问题的延续：IntegrationFlow Amqp Channel Adapter is not working in handle()

你有这个：

@Bean
public StompInboundChannelAdapter stompInboundChannelAdapter() {
    StompInboundChannelAdapter adapter = new StompInboundChannelAdapter(stompSessionManager(), "/queue/myQueue");
    adapter.setOutputChannel(stompInputChannel());
    adapter.setPayloadType(ByteString.class);
    return adapter;
}

您没有在此处显示。

问题是您随后在 IntegrationFlow 中使用了相同的定义。事实证明，StompInboundChannelAdapter bean 较早启动，然后处理 IntegationFlow，并订阅 .transform(inBoundStompMsgTransformer::transform) 以处理传入消息。

因此，如果您从 stompInboundChannelAdapter() 中删除 @Bean，它应该可以正常工作。待会儿再看看为什么MessageProducerSupport早点开始，然后IntegrationFlows...

延迟入站适配器和控制总线

Delayed Inbound Adapter and Control Bus

spring-integration

spring-integration-dsl