Visual Programming of Location-Based Services

"In this paper we discuss a visual programming environment for design and rapid prototyping of web applications, securely connected to remote Location-Based Services. This visual programming approach is based on computation as data transformation within a dataflow, and on visual composition of web services. The VisPro environment uses a very simple approach to service composition: (a) the developer takes a set of web widgets from a library, (b) builds a user interface by drag and drop, (c) builds the application logic of the web service by drawing the connections between boxes (standing for suitable data transformations) and widgets (standing for user interaction). The development session produces, in presentation mode, a web page where the user may trigger, and interact with, the resulting compound service and related computations. A successful GUI (and logic) is abstracted as a new service, characterized as a widget, and stored in the widget library.