Create a Java class called com.packt.microservices.geolocation.GeoLocationApplication.java and give it an empty main method:

        package com.packt.microservices.geolocation;  
          public class GeoLocationApplication {  
            public static void main(String[] args) { 
            // left empty intentionally 
           } 
          } 

Now that we have our basic template project, let's make our project a child project of Spring Boot's spring-boot-starter-parent pom module. This module has a lot of prerequisite configurations in its pom.xml file, thereby reducing the amount of boilerplate code in our pom.xml file. At the time of writing this, 1.3.6.RELEASE was the most recent version:

        <parent> 
          <groupId>org.springframework.boot</groupId> 
          <artifactId>spring-boot-starter-parent</artifactId> 
          <version>1.3.6.RELEASE</version> 
        </parent> 

After this step, you might want to run a Maven update on your project as you have added a new parent module. If you see any warnings about the version of the maven-compiler  plugin, you can either ignore it or just remove the <version>3.5.1</version> element. If you remove the version element, please perform a Maven update afterward.

Spring Boot has the ability to enable or disable Spring modules such as Spring MVC, Spring Data, and Spring Caching. In our use case, we will be creating some REST APIs to consume the geolocation information of the users. So we will need Spring MVC. Add the following dependencies to your pom.xml file:

        <dependencies> 
          <dependency> 
            <groupId>org.springframework.boot</groupId> 
            <artifactId>spring-boot-starter-web</artifactId> 
          </dependency> 
        </dependencies> 

We also need to expose the APIs using web servers such as Tomcat, Jetty, or Undertow. Spring Boot has an in-memory Tomcat server that starts up as soon as you start your Spring Boot application. So we already have an in-memory Tomcat server that we could utilize.

Now let's modify the GeoLocationApplication.java class to make it a Spring Boot application:

        package com.packt.microservices.geolocation; 
        import org.springframework.boot.SpringApplication; 
        import org.springframework.boot.autoconfigure
         .SpringBootApplication; 
          @SpringBootApplication 
          public class GeoLocationApplication { 
            public static void main(String[] args) {
            SpringApplication.run(GeoLocationApplication.class, args); 
           } 
          } 

Now that our Spring Boot application is all set to run, let's see how to run our microservice. Right-click on GeoLocationApplication.java from Package Explorer, select Run As, and then select Spring Boot App. You can also choose Java Application instead of Spring Boot App. Both the options ultimately do the same thing. You should see something like this on your STS console:

If you look closely at the console logs, you will notice that Tomcat is being started on port number 8080. In order to make sure our Tomcat server is listening, let's run a simple curl command. cURL is a command-line utility available on most Unix and Mac systems. For Windows, use tools such as Cygwin or even Postman. Postman is a Google Chrome extension that gives you the ability to send and receive HTTP requests. For simplicity, we will use cURL. Execute the following command on your terminal:

      curl http://localhost:8080

This should give us an output like this:

      {"timestamp":1467420963000,"status":404,"error":"Not
      Found","message":"No message available","path":"/"}