DDRAW: An Object-Oriented Design Tool

Abstract

In general, graphical tools are a powerful approach for engineering activities. During design and analysis they help to model both the problem and potential solutions. During testing or debugging they can provide a quick visual means of generating test cases. And finally, during maintenance, well-executed graphics can guide software engineers in the repair and extension of existing systems.

The philosophy for the development of ddraw was to elaborate a graphical design tool with wide application fields. ddraw allows the construction of hierarchical structures by the use of a small set of graphical elements. A system in ddraw consists of components and relations between those. Components in turn may contain one or more subcomponents. Each component is described by a name, a graphical element, a set of ports and a text field. As graphical objects the user can choose between predefined elements like circles, boxes, rounded boxes and self defined icons. Ports represent the interfaces of components and can be linked to other ports. Additionally, the text field allows the user to attach any semantical meaning to each component.

ddraw has been implemented on top of the X Window System and uses window techniques and pointing devices to make the construction of complex systems manageable. For example, it supports building up and breaking down hierarchies, moving, copying, editing, storing and restoring partial structures, etc. Thus, it is easy to realize top-down, middle-out, or bottom-up design. Furthermore, a survey window facilitates the navigation through the components and their hierarchical levels.

In order to keep ddraw as a general purpose tool, the created structures are stored in an application independent Model Description Language (MDL). Structures described in MDL contain the complete information about their topology as well as the graphical and semantical attributes of all components. Thus, systems designed with ddraw can further be used by other tools like code generators, syntax checkers, simulators, etc.