Software Design 2e - DIM

184The rationale for methodFigure 8.4 The link between the DVM and the virtual machine levels used on a computer.(Each method has a design virtual machine embodied within it, helping to determine suchaspects as the set of viewpoints used, the strategy, architectural assumptions, etc.)incorporated a virtual machine that was not well matched to that of any existingdesign method. Features such as the package and the task model that is provided forparallel operations required a DVM that addressed such issues as packaging and parallelism,a problem that has yet to be resolved in a completely satisfactory manner.The design methods that provide the topics of Chapter 13 and the following chaptershave been selected precisely because they provide a set of very different DVMs.Perhaps the main feature that they possess in common is that they all assume that thefinal system will be implemented using imperative programming forms.The management benefits of using design methods are (not surprisingly) linked tomany of the same issues as the technical benefits. In particular, the documentation ofa system is important both for the development of the system and for its maintenance.So from a management viewpoint, using a recognized design method will provide:nnna framework for recording decisions and reasons in a systematic manner;a set of procedures that should ensure consistency in the structure of a design, andin the structure of the interfaces between design components, so making it easier touse a team of designers on a large project;a framework that helps with identifying important progress milestones.