The substructure generated from the transform flow can be imploded into the module establish alarm conditions (which will now include the processing implied by select phone number). The incoming controller can be removed because it is unnecessary when a single incoming flow path is to be managed.Дў. Many modifications can be made to the first iteration architecture developed for the SafeHome monitor sensors subsystem. Software requirements coupled with human judgment is the final arbiter. Optimal structural characteristics cannot be achieved. There are times, for example, when the controller for incoming data flow is totally unnecessary, when some input processing is required in a module that is subordinate to the transform controller, when high coupling due to global data cannot be avoided, or when Refinements are dictated by the analysis and assessment methods described briefly, as well as practical considerations and common sense. Modules are exploded or imploded to produce sensible factoring, good cohesion, minimal coupling, and most important, a structure that can be implemented without difficulty, tested without confusion, and maintained without grief. A first-iteration architecture can always be refined by applying concepts of module independence. Refine the first-iteration architecture using design heuristics for improved software quality.

However, further refinement and additions occur regularly during this period of design. The narrative serves as a first-generation Design Specification. A completed first-iteration architecture is shown in figure. Each of the data conversion or calculation transforms of the transform portion of the DFD is mapped into a module subordinate to the transform controller. The transform center of monitor sensors subsystem software is mapped somewhat differently. Factoring is again accomplished by moving outward from the transform center boundary on the incoming flow side. Second-level factoring for incoming flow follows in the same manner. Review and refinement may lead to changes in this structure, but it can serve as a 'first-iteration' design. Practical considerations and measures of design quality dictate the outcome of secondlevel factoring. Two or even three bubbles can be combined and represented as one module (recalling potential problems with cohesion) or a single bubble may be expanded to two or more modules. Although the figure illustrates a one-to-one mapping between DFD transforms and software modules, different mappings frequently occur.

Dfd software engineering