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Microservice Registration With Spring Cloud Using Netflix Eureka - Part 2

This is the second article in a series of 5 articles covering service discovery in microservices architecture using SpringBoot and Netflix Eureka:

Part 1 - Overview of Netflix components.

THIS - Develop an Student service to produce and consume REST API using Spring Boot

Part 3 - Use Eureka for Service Registration

Part 4 - Use Eureka for Service Discovery

Part 5 - Load balancing using Netflix Eureka + Ribbon

In this post, we will be creating 2 services - student producer and student consumer. As the name suggests, the student-producer will be exposing REST APIs which will be consumed by the student-consumer.

So, let’s start with student producer. The maven project structure will look like this-

Eureka1

Add these spring dependencies in the pom.xml file:

<?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>org.example</groupId>
    <artifactId>student-producer</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.1.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <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>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

Create the model class Student:

package com.stackdev.model;

public class Student {
    private String sId;
    private String name;
    private Integer className;

    public Student() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getClassName() {
        return className;
    }

    public void setClass(Integer className) {
        this.className = className;
    }


    public String getsId() {
        return sId;
    }

    public void setsId(String sId) {
        this.sId = sId;
    }

}

Create the controller as:

package com.stackdev.controllers;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.stackdev.model.Student;

@RestController
public class TestController {
    @RequestMapping(value = "/student", method = RequestMethod.GET)
    public Student firstPage() {
        Student s = new Student();
        s.setName("emp1");
        s.setClass(12);
        s.setsId("1");

        return s;
    }
}

The SpringBootHelloWorldApplication main class will look like this:

package com.stackdev;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class SpringBootHelloWorldApplication {
    public static void main(String[] args) {
        SpringApplication.run(SpringBootHelloWorldApplication.class, args);
    }
}

Now compile and run the application. Go to localhost:8080/student You will see the response:

Eureka2

Now, we’ll create student-consumer project. The project structure will look like this:

Eureka3

Add the following dependancies in the pom.xml file:

<?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>org.example</groupId>
    <artifactId>student-consumer</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.1.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <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>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Define the controller to consume the service exposed by student-producer above using the REST Template as follows-

import java.io.IOException;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestClientException;
import org.springframework.web.client.RestTemplate;

@RequestMapping(value = "/student/consumer", method = RequestMethod.GET) public String getStudent() throws RestClientException, IOException {

		String baseUrl = "http://localhost:8080/student";
		RestTemplate restTemplate = new RestTemplate();
		ResponseEntity<String> response=null;
		try{
		response=restTemplate.exchange(baseUrl,
				HttpMethod.GET, getHeaders(),String.class);
		}catch (Exception ex)
		{
			System.out.println(ex);
		}
		System.out.println(response.getBody());
	}

	private static HttpEntity<?> getHeaders() throws IOException {
		HttpHeaders headers = new HttpHeaders();
		headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);
		return new HttpEntity<>(headers);
	}
}

Finally create the Bean for the above controller, load it and call the getStudent() Method.

package com.stackdev;

import java.io.IOException;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestClientException;

import com.stackdev.controllers.ConsumerControllerClient;

@SpringBootApplication
public class SpringBootHelloWorldApplication {

	public static void main(String[] args) throws RestClientException, IOException {
		ApplicationContext ctx = SpringApplication.run(
				SpringBootHelloWorldApplication.class, args);
		
		ConsumerControllerClient consumerControllerClient=ctx.getBean(ConsumerControllerClient.class);
		System.out.println(consumerControllerClient);
		consumerControllerClient.getStudent();
	}
	
	@Bean
	public  ConsumerControllerClient  consumerControllerClient()
	{
		return  new ConsumerControllerClient();
	}
}

Now run the application. Check the console for the response:

Eureka4

In the next post we will develop a Eureka Server microservice using Spring Boot and register our student-producer service to it.

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