The Design Environment

Abstract

The core modeling component of the YAWL System is the Editor. This tool enables workflow designers to graphically define complex process models, and to analyze and export these models to the Engine. Specifically, the Editor is a rich client application offering visual support for the definition of the process control logic, the data associated with the process and its tasks, and the organizational resources participating in the process. An important aspect of the Editor is the provision of sophisticated logic to verify the produced models. Through this capability, a designer can pinpoint syntactical and semantic issues at a mouse click, so as to avoid potentially costly mistakes before deploying a process to a workflow engine. The main driver behind the development of a visual editor for YAWL was the necessity to speed up the creation of process models and to foster the uptake of the language by nontechnical users. In light of this, the Editor had to fulfill the requirements of free availability, portability, ease of use, and interoperability. The tool had to be freely available; therefore, it was decided to release it under the open source LGPL license. Portability was guaranteed by developing the Editor in Java^TM and avoiding any code dependency on OS-specific libraries. Ease of use was achieved by providing the Editor with an intuitive user interface on top of a core graphical component based on extensions to the JGraph libraries.¹ Interoperability was supported by the definition of a common XML format and a set of API calls for the exchange of workflow specifications between an editor and the runtime environment (cf. Chap. 9). The interaction between design and runtime environment in the YAWL System is depicted in Fig. 8.1.