The Timewheel Group Communication System

This paper describes a group communication system called the timewheel group communication system that has been designed for a timed asynchronous distributed system model. The timewheel group communication system consists of three protocols: a clock synchronization, an atomic broadcast protocol, and a group membership protocol. All these protocols have been designed to be fail-aware in the sense that a process can detect at any point in time whether any of its properties is violated. Although these protocol have been designed to operate in an asynchronous distributed computing environment, they provide timeliness properties. The timewheel group communication system provides nine group communication semantics that a user can dynamically choose from while broadcasting an update. This system provides high throughput, fast delivery and stability times, uses a small number of messages per update broadcast, and distributes evenly the processing load among group members. The good overall performance is maintained in the absence of any failures and normal update arrival rates, in the presence of communication or process failures, and under very fast or very slow update arrival rates.