Abstract: Research can rarely be performed on open platform based large scale distributed systems which always consist of heterogeneous sub-systems and heterogeneous hardware and software components. It is not also pursued to realize the integration of these sub-systems, highly reliable system operations and high productivity of application software development. Our solution is a Cooperating Autonomous Decentralized System Architecture which is an extendible concept of the conventional Autonomous Decentralized System Architecture. The new system architecture is a novel synthesis of four design principles: highly extensible addressing architecture, core communication protocols with minimal semantics, sophisticated network traffic control techniques and reliable communication control mechanism. The current implementation provides both flexibility and high reliability for integrating heterogeneous sub-systems, and it has been proven in several commercial systems.