Abstract :
The paper draws on the results emerging from two projects: SPIRITS (supporting predictable implementation of requirements in timing and safety) and DORIS (data orientated requirements implementation scheme). The SPIRITS and DORIS acronyms accurately reflect the main thrust of the work, with a strong emphasis on the timing and integrity properties of systems whose development is based on data flow principles. A set of symbols is described which can be used to capture, with considerable precision, the dynamic effects of interactions between a system and its environment, and between the components within the system. Each symbol represents a form of data flow, and it is shown how the dynamic characteristics can be preserved whatever the distribution of the functions of the system in its operating environment. A number of examples are used to illustrate the approach, and the nature of various temporal effects is discussed
