Spring Cloud Stream Tutorial - Publish Message To RabbitMQ Simple Example

Spring Cloud - Table Of Contents

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.javainuse</groupId> <artifactId>employee-registration-producer</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>employee-registration-producer</name> <description>Demo project for Spring Cloud Stream publishing</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath />  </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> <spring-cloud.version>Edgware.SR1</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-stream-rabbit</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>0</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>

Create the Spring Boot Bootstrap class with the SpringBootApplication annotation as follows-

   package com.javainuse;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class EmployeeRegistrationApplication {

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

Next we define the model class Employee-

   package com.javainuse.model;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
public class Employee {

	private String empName;
	private String empID;

	public String getEmpName() {
		return empName;
	}

	public void setEmpName(String empName) {
		this.empName = empName;
	}

	public String getEmpID() {
		return empID;
	}

	public void setEmpID(String empID) {
		this.empID = empID;
	}

	@Override
	public String toString() {
		return "Employee [empName=" + empName + ", empID=" + empID + "]";
	}

}

Next define the Source class. This will simply be an interface that defines ways of obtaining the MessageChannel object needed to send the message. Here we define the output channel named as employeeRegistrationChannel.

   package com.javainuse.source;

import org.springframework.cloud.stream.annotation.Output;
import org.springframework.messaging.MessageChannel;

public interface EmployeeRegistrationSource {

	@Output("employeeRegistrationChannel")
	MessageChannel employeeRegistration();

}

Next we define a simple controller that will make use of the above defined classes to publish the message upon receiving the employeeRegistration request. Here the @EnableBinding annotation tells Spring Cloud Stream that you want to bind the Controller to a message broker.

   package com.javainuse.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.integration.support.MessageBuilder;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.javainuse.model.Employee;
import com.javainuse.source.EmployeeRegistrationSource;

@RestController
@EnableBinding(EmployeeRegistrationSource.class)
public class EmployeeRegistrationController {

	@Autowired
	EmployeeRegistrationSource employeeRegistrationSource;

	@RequestMapping("/register")
	@ResponseBody
	public String orderFood(@RequestBody Employee employee) {
		employeeRegistrationSource.employeeRegistration().send(MessageBuilder.withPayload(employee).build());
		System.out.println(employee.toString());
		return "Employee Registered";
	}
}

Finally we specify the properties. Here we specify the RabbitMQ properties. Also we associate the channel to the queue to be used -

   server.port=8080
spring.rabbitmq.host=localhost
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

spring.cloud.stream.bindings.employeeRegistrationChannel.destination=employeeRegistrations
spring.cloud.stream.default.contentType=application/json

We are done with the required Java code. Now lets start RabbitMQ. As we had explained in detail in the Getting started with RabbitMQ perform the steps to start the RabbitMQ.
Next start the Spring Boot Application by running it as a Java Application. Create a POST request with payload as follows
Spring Cloud Stream Example

Send the above request, it trigger the message to be sent to the RabbitMQ.
Next go to the RabbitMQ console-http://localhost:15672/. We can see in the Exchange section, an exchange named employeeRegistration gets created and it has one message.
Spring Cloud Stream RabbitMQ Example

In the next tutorial we will see how to bind this exchange to a queue and consume this RabbitMQ message using Spring Cloud Stream.

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Spring Cloud Stream - RabbitMQ Publish Message Example

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Spring Cloud Stream Tutorial - Publish Message to RabbitMQ Simple Example

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