Concern Space Model Based Separation Of Concern: A Theory And Applications

Separation of concern (SoC) is one of the most important principles of software engineering. However, with the increasing complexity of software, more and more concerns fail to be separated effectively because of the fact that traditional SoC techniques allow only one way of decomposing a system. Effective and adequate SoC requires that a system be decomposed along more than one way simultaneously, and that all modules into which the system is decompose be able to be composed seamlessly into a whole system at every stage of software lifecycle. Concern space model is proposed to organize and manage concerns, via which the corresponding artifacts are affected.This paper discusses the theory and application of concern space model based SoC. First, it proposes the concepts of conceptual decomposition model and physical decomposition model, based on which it addresses the problems arising from hierarchical decomposition of traditional SoC techniques and shows how to solve them by using crosscutting decomposition. Subsequently, how to design and implement composition mechanism and decomposition mechanism to achieve crosscutting decomposition is exemplified. We consider conceptual decomposition model, physical decomposition model and composition mechanism and decomposition mechanism used through these two kinds of models as the unified foundation of SoC.After that, based on the theory of the unified foundation of SoC, this paper discusses and analyzes the necessity of modeling concerns, and then introduces the concept of concern space model. Later, a general concern space model (Gecosm) is proposed based on the requirements that an effective concern space model should meet, which is drawn from analyzing and comparing the existing concern space models.Lastly, the tool support for Gecosm is presented, with which a case study initially applying the theory of concern space model based SoC is conducted. A conclusion is arrived from this case study that concern space model based SoC can be used to effectively separate concerns, and can reduce software complexity and increase software understandability by organizing and managing concerns on the level of abstraction of concerns which in turn affects the concrete manifestation of concerns.