Enhancing Real-Time Event Service for Synchronization in Object-Oriented Distributed Systems

Distributed object computing middleware such as CORBA, RMI, and DCOM have gained wide acceptance and has shielded programmers from many tedious and error-prone aspects of distributed programming. In particular, CORBA Event Service has been used extensively in embedded systems. In this paper, we propose an aspect oriented approach to develop synchronization code for distributed systems that use event service as the underlying communication middleware. Our approach is to factor out synchronization as a separate aspect, synthesize synchronization code and then compose it with the functional code. We use high-level ”global invariants” to specify the synchronization policies which are then automatically translated into synchronization code for the underlying event service. To implement synchronization efficiently using the event service, we propose enhancements to the semantics of the event service. Specifically, we define the notion of condition events and exactly k semantics. Given these enhancements, we describe a synthesis procedure to translate global invariants into synchronization code based on events. We describe the implementation of the enhancements on the Tao’s Real-Time Event Service. We present experimental results to demonstrate that the enhanced event service leads to more efficient implementation of synchronization. We feel that our methodology and the enhanced Real-Time Event Service will lead to more confident use of sophisticated synchronization policies in distributed object oriented systems.