When building a graphical user interface to run on multiple operating systems, there are many toolkits to choose from. Many traditional toolkits require deploying object code or byte-code to each computer, which requires periodically updating each computer with the latest code. Since nearly all computers have web browsers, an alternative is to write a GUI using a web browser. Current web browsers now support HTML/XHTML, JavaScript, CSS, AJAX, Forms, DHTML, SVG/VML/Canvas that provide a high level of interactivity.

Therefore, I chose to use a web-based toolkit to write a GUI to control the S-Pol and CHILL radars. There are also many web-based toolkits I could have used to write the radar control GUI. I chose the Wt toolkit. One advantage of using Wt was that I could write my application in C++, allowing me to use existing C/C++ libraries for communication to other applications. Another advantage of Wt is that Wt generates the secure, browser specific, JavaScript and AJAX code required for dynamically updating web pages. Writing a web application that avoids security issues, such as "Cross Site Scripting" can be challenging, but Wt generates its own secure and browser-portable code. Wt provides a set of widgets and a signal/slot implementation that closely resembles the Qt toolkit, which makes it fairly straightforward to generate a complex program that decouples the user interface from the data model. Wt allowed me to write a GUI that runs on a single server, yet provides remote or local access from Windows, Linux, or Mac computers.

I will demonstrate a GUI written in Wt for the S-Pol and CHILL radars, with many of the usual "widgets", along with a "drag-and-drop" interface.