ProducerApplication.java

package demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.annotation.Output;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;


@EnableBinding(MessageChannels.class)
@RestController
@SpringBootApplication
public class ProducerApplication {

    private final MessageChannels channels;

    @Autowired
    public ProducerApplication(MessageChannels channel) {
        this.channels = channel;
    }

    @RequestMapping(method = RequestMethod.GET, value = "/greet/{name}")
    void greet(@PathVariable String name) {
        Message<String> msg = MessageBuilder.withPayload(name).build();
        this.channels.output().send(msg);
    }

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

interface MessageChannels {

    @Output
    MessageChannel output();
}