Software Design 2e - DIM

16The nature of the design processgreater degrees of specialization, however, and we are unlikely to find an aeronauticalengineer producing the design for a new oil tanker! This degree of specialization is lessmarked though in software development, which in some ways harks back to the moregeneralist practices witnessed in an earlier era – whilst being applied across what is inmany ways a much wider range of domains. Admittedly a specialist in (say) databasedesign might hesitate to design a real-time control system (or at least, ought to hesitate)but, in principle, one person could possess the necessary expertise to design bothtypes of application.One of the problems that this introduces, therefore, is that a software designermay need to acquire some degree of ‘domain knowledge’ as a routine part of the inputneeded for undertaking any particular design task. Some of this may be obtained fromthe specification (which may well run to hundreds of pages), but by no means all of thenecessary knowledge is likely to be available in this way. So, as shown in Figure 1.7,the software designer may need to be responsive to many channels of communication.This is an aspect that will be addressed further in Chapter 3, while some of theways of transferring the domain knowledge will also be examined more fully in laterchapters.To continue with the needs of software development: it is clear from the abovethat the main task of the design phase is to produce the plans necessary for softwareproduction to proceed. The form and extent of the plans will be determined by thedesign practices and means of implementation chosen, as well as by the size of theRequirementsspecificationPlans forrealizationof the designConstraintsDomain knowledgeFigure 1.7The designer’s channels of communication.