多任务CAD系统的执行中心模型

针对直接操纵的多任务CAD系统的实时反馈、并发对话等需求，提出CAD 系统的基于事件驱动的层次化执行中心模型EDHM。该模型遵循对话独立性原则，将执行中心划分为3个层次5大部件，支持连续语义反馈和异步并发对话，并以统一的框架支持顺序和异步交织的交互风格。此模型已被应用到多任务CAD支撑系统OpenDesign的执行中心构造中。实践表明，基于EDHM模型建立的执行中心满足直接操纵和多进程的需求，具有结构上的独立性，易于移植和封装复用。

Model of Execution Center in Multi-Task CAD Systems

We present the Event Driven Hierarchy model (EDHM) of execution center, aiming at fulfilling the requirements of direct manipulation such as real time feedback and concurrent dialog in multi task CAD systems. The EDHM model conforms to the principle of independence for human computer interaction, divides the execution center into three levels and five modules. It supports continuous semantic feedback and asynchronous concurrent interaction, provides the mixed styles of interaction in a uniform framework. This model has been applied to the construction of execution center of OpenDesign (a CAD supporting system) and is proved to be a solid base for the modeling and implementation of efficient execution centers that support direct manipulation and multi process. In addition, execution center based on EDHM model is independent in structure, thus is easy to port and reuse.