Skeblle: A new kind of diagramming tool with programmable active diagrams

Abstract

Diagramming tools range from manual free-form drawing tools to pre-programmed notation specific tools for UML or SDL, and further to fully programmatic tools like Pic or TikZ. In such tools, the diagrams are the end product, not available for further use, unaware of relations between diagrams or the ability to express one diagram as a function of another. We propose a new kind of tool based on programmable active diagrams, where diagrams are active entities to be operated upon and connected to systems they depict. Our tool, Skeblle, implements this approach for box-line diagrams. In Skeblle, every diagram drawn by a user is backed by a graph, and both the diagram and the underlying graph can be manipulated manually or with a command language. Manipulations of the graph are reflected in the diagram and vice versa, and the graph can link real systems to diagram nodes via urls. In combination, these facilities give us a novel tool that feels like a simple diagramming tool, but is capable of creating diagrams that better capture the domain they represent. Diagrams can change to reflect changes in systems they depict, and may be operated upon to compute related diagrams. We describe how Skeblle may be used to draw software deployment and architecture diagrams, explain distributed protocols, and visualize chemical reactions. We show that Skeblle makes it simple to compute diagrams to illustrate differences in system states due to component failures, data flows, and chemical interactions.