title: Wrapper, Filter and Servlet
body: <p>since I am new to Servlet programming, it is possible that I ask a basic question. </p>
  
  <p>I am writing an application where a Filter gets the response from a servlet, and does some computation with it. I found out that I need a wrapper class to catch the response. </p>
  
  <p>My question now is why the wrapper is needed? Thanks in advance!</p>