title: How to make Patch-able/Update-able application?
body: <p>I have completed a student project, this project extract data from xml files on internet and save to database and displays it. And i use that data in a few different ways e.g. display on main page, in another tab as a table, and to create some graphs.</p>
  
  <p>I did all this by making 5 different classes. Each class extracts different type of XML and save it to database with a single Load() function.</p>
  
  <p>Last requirement of the project is to make the application Update-able/Patch-able (user does not need to download the whole new build to update the application, instead a small patch installer will add feature to application). How do i do that? My teacher says that adding polymorphism will help, a friend says that create different modules of application (break it into parts) so that each class will have its own dll. </p>
  
  <p>What steps i need to do to make it patch-able? How to create dll of classes? how to break application into parts? Or all of this is unnecessary, i should just use a patching software that creates a patch by comparing both builds??</p>