title: Why we use service classes in spring hibernate integration
body: <p>I want to know the use of service classes in J2EE. </p>
  
  <p>I have 2 projects.</p>
  
  <p>One is in spring hibernate integration.That project contain DAO,MODEL,SERVICE and CONTROLLER.Within that The request is access by the controller and send to the values to the dao class through the service class.</p>
  
  <p>2nd project contain only BEAN,CONTROLLER and DERIVED classes.Within that the request is access by the controller and send the values directly to the derived class.Query is written in this derived class.</p>
  
  <p>I want to know the difference between these two projects. Why we use service class ? </p>