Updating the noticeboard using the Refresher add-on

This recipe is about the online sharing of information between more applications. We will create a public noticeboard, as in the following screenshot. Users can open this application in web browsers on different computers. Each of them sees the same, shared board. Users can move and edit any note and other users can see it live. In this recipe, we will see how to use the Refresher add-on. This component makes it possible to make UI changes, even if the user does not start a transaction.

Getting ready

1. We create a Vaadin project with main UI class called Demo.

   public class Demo extends UI {…}
   

2. We will use the Refresher add-on. We download it from the Vaadin directory at http://vaadin.com/addon/refresher and put the JAR file in our web project under the WebContent/WEB-INF/lib directory.

3. Or we can add Maven dependency according to instructions on the mentioned web page.

4. Then we recompile this add-on. In Eclipse, we can do it by pressing Ctrl + 6...