Modelling Architectures for Dynamic Systems

A dynamic system is one that changes its configuration as it runs. It is a system into which we can drop new components that then cooperate with the existing ones. We are concerned with formally defining architectures for such systems and with realistically validating designs for applications that run on those architectures. We describe a generic architecture based on the familiar registry services of CORBA, DCOM and Jini. We illustrate this architecture by formally describing a simple point-of-sale system built according to this architecture. We then look at the sorts of global properties that a designer of applications would wish a robust system to have and discuss variations on the architecture which make validation of applications more practical.