The Network Data Delivery Service: Real-Time Data Connectivity for Distributed Control Applications

The Network Data Delivery Service (NDDS) is a novel network data-sharing system. NDDS builds on the model of information producers (sources) and consumers (sinks). Producers generate data at their own discretion, unaware of prospective consumers. Consumers \subscribe" to data-updates without concern for who is producing them. The routing protocol is connectionless and nearly \stateless," thus network recongurations, node failures, etc. are handled naturally. This scheme is particularly e ective in systems (such as distributed control systems) where information is of a repetitive nature. NDDS provides support for multiple producers, reliable data-delivery, consumer update guarantees, noti cations vs. polling for updates, dynamic binding of producers and consumers, distributed queries, userde ned data types etc. NDDS is integrated into the ControlShell real-time framework and is being used in several robotic applications as an e ective means of information sharing between sensor systems, robot controllers, planners, graphical user interfaces, simulators etc.