HTML5 / CSS / JavaScript

The user interfaces developed using RapidClipse are based on HTML5, CSS, and JavaScript and run in the web browser of the client without the need for any additional plugin.  

Java

With RapidClipse, you develop your applications completely in Java. The HTML5 user interface is dynamically generated at runtime. You do not need to interact with any HTML5 or JavaScript at any time.

Vaadin

The Java UI code generated by RapidClipse is based on the Vaadin framework. Vaadin consists of a client side and a server side.

Source: Vaadin documentation.

Server side

The server side of Vaadin allows you to develop the entire interface in Java. In this regard, Vaadin is very similar to Java Swing. The UI code is automatically generated by the RapidClipse GUI Builder so that you don't have to write it by hand. At runtime, the server-side Vaadin application runs in a Servlet container on the server, delivers the interface to the client, handles the User Session Management and the requests of individual clients, and automatically updates the interface in the event of changes, so that you do not have to perform any of these tasks manually.

Client side

On the client side, Vaadin offers an AJAX-based JavaScript engine that renders the user interface in the browser. The JavaScript UI widgets that achieve this are based on GWT (Google Web Toolkit) code, which was generated using the GWT compiler. The Vaadin client-side engine sends every user interaction to the server side and updates the interface, thereby ensuring both sides are fully synchronized. The communication takes place asynchronously via HTTP or HTTPS requests. 

Themes

The design and appearance of the interface can be defined using CSS or SCSS. Several high-quality themes are available with Vaadin by default.

Google Web-Tookit (GWT) 

GWT is a Java Framework that includes a Java to JavaScript compiler with which it is possible to entirely implement HTML/JavaScript user interfaces in Java. At the final point, the client-side Java code is converted to JavaScript code by using the GWT compiler. The JavaScript code generated by GWT can be executed by the browser and already contains optimizations for all major browsers on all platforms, including Windows, Linux, Mac OS X, Android, iOS, and Windows Mobile. Since RapidClipse provides a widget palette that has already been pre-compiled by Vaadin, you won’t have to grapple with GWT in RapidClipse unless you want to develop your own UI widgets.