A C++ framework for active objects in embedded real-time systems-bridging the gap between modeling and implementation

In research communities it is now well-accepted that the object paradigm provides a good foundation for the challenges of concurrent and distributed computing. For practitioners, however, it is not without problems to combine the concepts of processes and objects. A major reason for this is that the predominant object-oriented programming language in industry, C++, does not support concurrency. In this paper we present a simple and powerful approach to extending C++ with constructs for concurrent programming. We discuss the design, application, and implementation of a framework that supports standard concurrency constructs and, contrary to what is suggested in several books on object oriented modeling techniques for real-time systems, we demonstrate that it is possible to integrate the notions of object and process and maintain a smooth-virtually non-existing-transition from modeling to implementation. The framework has been used at Bang and Olufsen, a major Danish manufacturer of audio and video equipment, to develop software for a CD player; we illustrate the strength of the approach with examples from this project. As a pleasant side benefit, the framework approach results in a considerable reduction of the code size of more than 50% compared to earlier versions of the system.