Imagine you're driving on a highway (your program is running). Suddenly, a tyre gets punctured (an exception occurs). If you don't have a spare tyre (no exception handling), you're stuck on the road ...
It encapsulates a Web server (for now, Jetty) on the backend side, and use GWT on the frontend side. So, with PonySDK, you will be able to write standard Java code for creating your Web application.