A communication micro-kernel for Implementing Object-Oriented programming on Closely Coupled Distributed Architectures

Within the framework of distributed object-oriented programming, this paper illustrates the main features of a communication micro-kernel able to perform, in a transparent way, both local and remote communications among objects located on a network of closely coupled microcomputers. The communication micro-kernel allows one to address an object by specifying its virtual location, which usually corresponds to a set of microcomputers considered as a whole. By default, an object is allowed to migrate within the bounds of a given virtual location; hence, any migration activity may occur without overloading the network with broadcast messages. As a high-level environment, a non-standard CLOS-like interpreter, enhanced with message passing capabilities, has been defined and used to test the communication micro-kernel. Due to the virtualization capabilities provided by such an environment, both an application and the network where the application is intended to be run can be decomposed into several layers and then merged together, thus making it possible to meet hardware and software requirements at a suitable level of abstraction. We believe that the described communication micro-kernel will turn out to be very useful in building adaptive systems and in improving their load-balancing by dynamically performing object / method migration.