Unix tools as visual programming components in a GUI-builder environment

Development environments based on ActiveX controls and JavaBeans are marketed as “visual programming” platforms; in practice their visual dimension is limited to the design and implementation of an application’s graphical user interface (GUI. The availability of sophisticated GUI development environments and visual component development frameworks is now providing viable platforms for implementing visual programming within general-purpose platforms, i.e. for the specification of non-GUI program functionality using visual representations. We describe how specially-designed reflective components can be used in an industry-standard visual programming environment to graphically specify sophisticated data transformation pipelines that interact with GUI elements. The components are based on Unix-style filters repackaged as ActiveX controls. Their visual layout on the development environment canvas is used to specify the connection topology of the resultant pipeline. The process of converting filter-style programs as visual controls is automated using a domainspecific language. We demonstrate the approach through the design and the visual implementation of a GUI-based spelling checker.