Abstract : Visual programming languages (VPLs) provide notations for representing both the intermediate and the final results of a knowledge engineering process. Whereas some VPLs particularly focus on control flow and/or data flow of a software, very few VPLs stress on the interactive dimension of application (dialogue flow). This paper focuses on a VPL allowing designers to specify interactions between a user and a system, in the field of Web-based geographic applications. We first present the underlying interaction model that the VPL is based on, and then the detailed characteristics of the VPL. We show how this VPL has been integrated in a graphical design framework allowing designers to immediately assess their specification. Then we illustrate the way to use the framework from the design step to the final code generation step. Last, we detail an experimentation aiming at evaluating the strengths and the weaknesses of our VPL.