Http outbound gateway is working but not making the call - using spring integration DSL java

Question

I am a newbie in the spring integration framework. Below is my code, I am actually trying to make some HTTP calls using HTTP outbound gateway using SI DSL configuration. When I ran the code the IntegrationFlow methods are called but the HTTP hit is not making. I am not sure why.

Main class

@EnableIntegration
@Configuration
@Import({ AptHttp.class })
public class DemosiApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemosiApplication.class, args);
    }

}

config class

@Configuration
@IntegrationComponentScan
public class AptHttp {

    @EnableIntegration
    public static class ContextConfiguration {

        @Bean("inputChannel")
        public MessageChannel inputChannel() {
            return MessageChannels.direct().get();
        }

        @Bean
        public MessageChannel outputChannel() {
            return MessageChannels.direct().get();
        }

        @Bean
        public IntegrationFlow outBoundFlow() {
            System.out.println("Inside t outBoundFlow flow ");
            final String uri = "http://localhost:9090/api/test";
            return f -> f.channel(inputChannel())
                    .handle(Http.outboundGateway(uri).httpMethod(HttpMethod.GET).expectedResponseType(String.class))
                    .channel(outputChannel());
        }

    }

}

Above two classes only. I don't get any error too when I ran the SI application (sysout are printing but the call is not made I don't know why ). I have another application where I can have some API through the spring integration code I am trying to hit that API method. To understand the flow of HTTP outbound gateway I am trying this way.

Could anyone please help/ suggest me on this.

Answer 1

You don't show (or don't have) the code which sends messages into the inputChannel.

The Http.outboundGateway() is not an active components and its work has to be triggered by the request message.

Also there are two main phases in Spring application context: bean creation and runtime. So, you see that System.out.println() during bean creation phase. It has nothing to do with runtime when really a send over HTTP happens.

So, after crating and starting an application context (SpringApplication.run(DemosiApplication.class, args);) you need to take an inputChannel bean and send a Message<?> into it. Only after that your HTTP Outbound Gateway is going to be triggered.

See more info in samples: https://github.com/spring-projects/spring-integration-samples