屏障组件在spring集成中是如何工作的？

Question

我试图理解以下示例：https://github.com/spring-projects/spring-integration-samples/tree/d8e71c687e86e7a7e35d515824832a92df9d4638/basic/barrier

并使用java DSL重写它。

首先，我想了解那个示例中发生了什么。当然，我已经阅读了github的解释，但我仍然不明白。我在这里问是因为我知道SI团队负责人（该示例的作者）回答了所有标记为Spring集成的问题。

服务器配置：

<int-http:inbound-gateway request-channel="receiveChannel"
                            path="/postGateway"
                            error-channel="errorChannel"
                            supported-methods="POST"/>

    <int-http:inbound-gateway request-channel="createPayload"
                            path="/getGateway"
                            error-channel="errorChannel"
                            supported-methods="GET"/>

    <int:transformer input-channel="createPayload" output-channel="receiveChannel" expression="'A,B,C'" />

    <int:channel id="receiveChannel" />

    <int:header-enricher input-channel="receiveChannel" output-channel="processChannel">
        <int:header name="ackCorrelation" expression="headers['id']" />
    </int:header-enricher>

    <int:publish-subscribe-channel id="processChannel" />

    <int:chain input-channel="processChannel" order="1">
        <int:header-filter header-names="content-type, content-length" />
        <int:splitter delimiters="," />
        <int-amqp:outbound-channel-adapter amqp-template="rabbitTemplate"
            exchange-name="barrier.sample.exchange" routing-key="barrier.sample.key"
            confirm-ack-channel="confirmations"
            confirm-nack-channel="confirmations"
            return-channel="errorChannel"
            confirm-correlation-expression="#this"/>
    </int:chain>

    <!-- Suspend the HTTP thread until the publisher confirms are asynchronously received -->

    <int:barrier id="barrier" input-channel="processChannel" order="2"
        correlation-strategy-expression="headers['ackCorrelation']"
        output-channel="transform" timeout="10000" />

    <int:transformer input-channel="transform" expression="payload[1]" />

    <!-- Aggregate the publisher confirms and send the result to the barrier release channel -->

    <int:chain input-channel="confirmations" output-channel="release">
        <int:header-filter header-names="replyChannel, errorChannel" />
        <int:service-activator expression="payload" /> <!-- INT-3791; use s-a to retain ack header -->
        <int:aggregator>
            <bean class="org.springframework.integration.samples.barrier.AckAggregator" />
        </int:aggregator>
    </int:chain>

    <int:channel id="release" />

    <int:outbound-channel-adapter channel="release" ref="barrier.handler" method="trigger" />

    <!-- Consumer -> nullChannel -->

    <int-amqp:inbound-channel-adapter channel="nullChannel"
        queue-names="barrier.sample.queue"
        connection-factory="rabbitConnectionFactory" />

    <!-- Infrastructure -->

    <rabbit:queue name="barrier.sample.queue" auto-delete="true" />

    <rabbit:direct-exchange name="barrier.sample.exchange" auto-delete="true">
        <rabbit:bindings>
            <rabbit:binding queue="barrier.sample.queue" key="barrier.sample.key" />
        </rabbit:bindings>
    </rabbit:direct-exchange>

据我所知，有三方：

• 客户
• 服务器
• rabbitMq

客户端将A、B、C发送到服务器

RequestGateway requestGateway = client.getBean("requestGateway", RequestGateway.class);
String request = "A,B,C";
System.out.println("\n\n++++++++++++ Sending: " + request + " ++++++++++++\n");
String reply = requestGateway.echo(request);

服务器接受该请求：

<int-http:inbound-gateway request-channel="receiveChannel"
                        path="/postGateway"
                        error-channel="errorChannel"
                        supported-methods="POST"

然后将一些值添加到消息标头中：

<int:header-enricher input-channel="receiveChannel" output-channel="processChannel">
        <int:header name="ackCorrelation" expression="headers['id']" />
    </int:header-enricher>

一些处理：

<int:chain input-channel="processChannel" order="1">
        <int:header-filter header-names="content-type, content-length" />
        <int:splitter delimiters="," />
        <int-amqp:outbound-channel-adapter amqp-template="rabbitTemplate"
            exchange-name="barrier.sample.exchange" routing-key="barrier.sample.key"
            confirm-ack-channel="confirmations"
            confirm-nack-channel="confirmations"
            return-channel="errorChannel"
            confirm-correlation-expression="#this"/>
    </int:chain>

如果我没有弄错的话，消息被分割，因此我们有3条消息AB和C，并发送到rabbitMq交换屏障。样品用钥匙交换。样品键

确实如此。接下来的步骤我还不清楚。你能澄清一下吗？

附笔。

我知道我们希望等待来自Rabbit的所有ACK消息，以确保我们传递给Rabbit的消息，当我们从Rabbit获得所有ACK时，我们希望回答客户端。但我不明白导致该结果的SI组件定义。您能否提供任何模式/图片/解释它是如何发生的？

更具体的问题：

为什么我们需要充实标题以及我们是如何做到的？

receiveChannel的目标是什么-愚蠢的问题

2个超文本传输协议服务-/postGateway和/getGateway在哪里。/postGateway用于从客户端获取msg、拆分成部分、发送到兔子、获取Acks然后回复给客户端。但是/getGateway的目的是什么？

目前，我的流定义如下所示：

    @Bean
public IntegrationFlow integrationFlow() {
    return IntegrationFlows.from(Http.inboundGateway("/spring_integration_post")
            .requestMapping(m -> m.methods(HttpMethod.POST))
            .requestPayloadType(String.class))
            .enrich(enricherSpec -> {
                enricherSpec.header("correlationId", 1); //or ackCorrelationId ?
            })
            .split(s -> s.applySequence(false).get().getT2().setDelimiters(","))
            .log()
            //.barrier(1000L) is it correct place for barrier?
            .log()
            .handle(Amqp.outboundAdapter(amqpTemplate())
                    .exchangeName("barrierExchange")
                    .routingKey("barrierKey"))
            .get();
}

我不知道怎么使用这里的屏障。

从服务器端，一切都在部分工作-我看到队列中的消息（在rabbitMq web界面上），但从客户端，我开始看到以下堆栈跟踪：

2019-08-28 22:38:43.432 ERROR 12936 --- [ask-scheduler-8] o.s.integration.handler.LoggingHandler   : org.springframework.messaging.MessageHandlingException: HTTP request execution failed for URI [http://localhost:8080/spring_integration_post]; nested exception is org.springframework.web.client.HttpServerErrorException$InternalServerError: 500 null, failedMessage=GenericMessage [payload=6, headers={id=36781a7f-3d4f-e17d-60e6-33450c9307e4, timestamp=1567021122424}]
    at org.springframework.integration.http.outbound.HttpRequestExecutingMessageHandler.exchange(HttpRequestExecutingMessageHandler.java:171)
    at org.springframework.integration.http.outbound.AbstractHttpRequestExecutingMessageHandler.handleRequestMessage(AbstractHttpRequestExecutingMessageHandler.java:289)
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:123)
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:169)
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115)
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:132)
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:105)
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73)
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453)
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:401)
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187)
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166)
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47)
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109)
    at org.springframework.integration.endpoint.SourcePollingChannelAdapter.handleMessage(SourcePollingChannelAdapter.java:234)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint.doPoll(AbstractPollingEndpoint.java:390)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint.pollForMessage(AbstractPollingEndpoint.java:329)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint.lambda$null$1(AbstractPollingEndpoint.java:277)
    at org.springframework.integration.util.ErrorHandlingTaskExecutor.lambda$execute$0(ErrorHandlingTaskExecutor.java:57)
    at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50)
    at org.springframework.integration.util.ErrorHandlingTaskExecutor.execute(ErrorHandlingTaskExecutor.java:55)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint.lambda$createPoller$2(AbstractPollingEndpoint.java:274)
    at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
    at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93)
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
    at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
    at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: org.springframework.web.client.HttpServerErrorException$InternalServerError: 500 null
    at org.springframework.web.client.HttpServerErrorException.create(HttpServerErrorException.java:79)
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:124)
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:102)
    at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63)
    at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:778)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:736)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:710)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:598)
    at org.springframework.integration.http.outbound.HttpRequestExecutingMessageHandler.exchange(HttpRequestExecutingMessageHandler.java:165)
    ... 30 more

Answer 1

这很简单；不清楚你不明白什么。

• 我们收到超文本传输协议的请求
• 我们为消息添加一个相关标头（标头增强器）
• 我们向Rabbitmq发送3条消息
• 我们需要等待确认-所以HTTP线程挂起在屏障中
• 3个确认异步返回
• 我们将响应聚合到一条消息中（使用相关标头）
• 我们将该消息发送到释放HTTP线程的屏障

接收器通道是标头增强器的输入通道。

您需要添加流来接收确认、聚合和触发屏障。