title: Portlets - Differences between setAttribute and setRenderParameter
body: <p>I'm a beginner with portlets, and I don't understand the difference between request.setAttribute and response.setRenderParameter (for an action). Both save an attribute into the request and allow to access to it after. I think specially about transmission between a processAction and the render which is just after the action method. </p>
  
  <p>I know that with setRenderParameter we cannot "stock" a complex object, but if I just want to transfer a String which one should I use?</p>
  
  <p>In which case should we use the <code>setRenderParameter</code> method or the <code>setAttribute</code> method ? </p>