Developing parallel object-oriented programs in the framework of VDM

After surveying the rely-guarantee and some related approaches to extending VDM to develop parallel programs, two main problems are found. One problem is that all explorations of parallelism are done in the stage of operation decomposition or afterwards so that the degree of parallelism is restricted. Another problem is that the atomicity is fixed at one level and the development complexity can not be controlled effectively because there is no natural means to let the level of granularity be under flexible control of the designer. In order to solve these two problems, we introduce a new concept — data decomposition which is based on the ideas of model split, modularisation and operation decomposition, and combine it with VDM to form a more general formal development method DD-VDM, in which some kind of operation decompositions, i.e., operation split can be done before some data reifications. Then a nested parallel object-oriented structure is proposed. Combining these ideas into the unified framework, this paper presents a hierarchical object-oriented design methodology in which two kinds of parallelism, that is, internal parallelism and service parallelism, can be exploited gradually and a kind of virtual atomicity is provided.This research is partially supported by China's National Foundation for Excellent Young Scientists.