Seamless Integration of Control Flow and Data Flow in a Visual Language

In the visual programming domain, the stress of research is laid on the use of visual formalism, which is considered to be more intuitive than the textual formalism, in the programming task. Some visual languages are based purely on data flow. With such languages, the execution order depends on the availability of data and it is therefore difficult to specify some programming constructs such as control structures. On the other hand, a pure control-flow based language has shortcomings with respect to data processing. Many visual languages based on the data-flow paradigm are supplemented with control structures to specify repetitive behavior in programs. In our case, the visual language initially used the control-flow paradigm. We then enriched this language with the integration of data-flow. This article presents the advantages of this integration. Then, it explains (mostly from the visual formalism point of view) how we decided to handle the combination of the two paradigms in our language, named DIVA-cd. The article presents through examples the specifications of various control structures in the DIVA-cd language.