How to implement POST http endpoint using spring integration?

Question

I have following configuration:

@Configuration
@EnableIntegration
@IntegrationComponentScan
public class Config {

    @Bean
    public IntegrationFlow integrationFlow() {
        return IntegrationFlows.from(Http.inboundGateway("/spring_integration_post")
                .requestMapping(m -> m.methods(HttpMethod.POST))
                .requestPayloadType(String.class)
        ).channel("responseChannel")
                .get();
    }
}

But when request I see following log on server side:

org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:138) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:105) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:401) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:431) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:284) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:265) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:223) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:129) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:169) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:132) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:105) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSendAndReceive(GenericMessagingTemplate.java:233) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSendAndReceive(GenericMessagingTemplate.java:47) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.AbstractMessagingTemplate.sendAndReceive(AbstractMessagingTemplate.java:46) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.integration.core.MessagingTemplate.sendAndReceive(MessagingTemplate.java:97) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.gateway.MessagingGatewaySupport.doSendAndReceive(MessagingGatewaySupport.java:499) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.gateway.MessagingGatewaySupport.sendAndReceiveMessage(MessagingGatewaySupport.java:470) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.http.inbound.HttpRequestHandlingEndpointSupport.actualDoHandleRequest(HttpRequestHandlingEndpointSupport.java:362) ~[spring-integration-http-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.http.inbound.HttpRequestHandlingEndpointSupport.doHandleRequest(HttpRequestHandlingEndpointSupport.java:253) ~[spring-integration-http-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.http.inbound.HttpRequestHandlingMessagingGateway.handleRequest(HttpRequestHandlingMessagingGateway.java:112) ~[spring-integration-http-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.java:53) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1039) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:853) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

I have no idea where should I subscribe. How can I write request handler to process request and prepare response ?

You need to show the configuration of the flow that is consuming from "responseChannel" - it sounds like you have nothing there (or the error is downstream). — Gary Russell, Aug 28 '19 at 13:32

score 1 · Accepted Answer · answered Aug 28 '19 at 13:33

First of all it doesn't look like you need an @IntegrationComponentScan. This one is especially for the @MessagingGateway parsing. If you don't use this kind of gateways, consider to remove it. More info in Docs: https://docs.spring.io/spring-integration/docs/5.2.0.BUILD-SNAPSHOT/reference/html/gateway.html#messaging-gateway-annotation

The Dispatcher has no subscribers clearly says that there is some DirectChannel bean and this one is not used anywhere as an inputChannel for subscription, e.g. via @ServiceActivator or IntegrationFlows.from().

Looking to the code you have provided, it feels like your .channel("responseChannel") goes without any downstream processing.

You need to get used to EIP principles and determine for yourself that everything in Spring Integration is connected via channels, but sometime if another side is missed (or stopped), you are going to have such an exception since there is no way to send and forget: the DirectChannel is just for EIP semantics and everything is called on the same thread like in plain Java code flow.

Could you list the options I have except the https://stackoverflow.com/a/57693946/2674303 ? — gstackoverflow, Aug 28 '19 at 13:49
As you can see I found that handle method can process requests and its return will be converted into response and send back to the client — gstackoverflow, Aug 28 '19 at 13:51
Right, But you miss the fact that there is an implicit channel between `Http.inboundGateway()` and `.handle()` anyway. And that is where you are subscribing. You could do something similar leaving your `.channel("responseChannel")` in the code and adding that `.handle()` afterwards. Another way is to have one more `IntegrationFlow` bean which could start from the ` IntegrationFlows.from("responseChannel")` and again with the `handle()`. My problem that I can't determine how you're going to process the message since there is no your custom code in the question. Therefore nothing in my answer. — Artem Bilan, Aug 28 '19 at 14:23

score 0 · Answer 2 · answered Aug 28 '19 at 13:45

Eventually I was able to solve the problem:

@Configuration
@EnableIntegration
public class Config {

    @Bean
    public IntegrationFlow integrationFlow() {
        return IntegrationFlows.from(Http.inboundGateway("/spring_integration_post")
                .requestMapping(m -> m.methods(HttpMethod.POST))
                .requestPayloadType(String.class))
                .handle((GenericHandler<String>) (payload, headers) -> "SERVER " + payload)
                .get();
    }
}

How to implement POST http endpoint using spring integration?

2 Answers2