A document illustrating the steps for creating a component, which provides a service.

To create a component that provides a service, you have to go through the following stages:

1. Write the service interface.

   The following example is the HelloService interface:

   package simple.service;
   
   public interface HelloService {
       
     public void hello();
   }

2. Write the service interface implementation class which will be the component's implementation class as well:

   Here is the HelloService implementation class:

   package simple.service.impl;
   import simple.service.HelloService;
   
   public class HelloServiceImpl implements HelloService {
   
     public void hello() {
               
        System.out.println("Hello components!");
     }
   }

3. Write the component description.

   The XML description of the HelloServiceComponent is the following.

   <?xml version="1.0" encoding="UTF-8"?>
   <scr:component name="HelloServiceComponent"
   xmlns:scr="http://www.osgi.org/xmlns/scr/v1.0.0">
     <!-- The component's implementation class-->
     <implementation class="simple.service.impl.HelloServiceImpl"/>
     <service>
        <!--The interface of the service provided by the component-->
        <provide interface="simple.service.HelloService"/>
     </service>  
   </scr:component>