Levels of atomic action in the Flagship parallel system

The Flagship system is a graph reduction machine having a distributed physical architecture. Although Flagship sits firmly in the declarative world, explicit state is supported to express the behaviour of the operating system. This state not only has to be isolated from the declarative aspects of the Flagship machine, but also has to be supported with respect to distribution. The mechanisms provided for maintaining consistency of state are discussed with respect to atomic actions at levels in the Flagship system. This approach is used to demonstrate how the software environment was supported by the basic execution mechanism of the machine. The nature, construction and creation of system software components are described and the structure of the system software is discussed with particular reference to optimizing access to distributed resources.