Software Design 2e - DIM

392indicate the degree of effort. A white box does not denote complete absence, onlya low level of emphasis.)Designing with objectsSo for this section we adopt a rather different structure to the one used to describemost of the methods in this book. First, we examine the purpose and nature of eachphase, and then we look at the five workflows, keeping throughout an emphasis uponthose issues most relevant to this book. (Hence, for example, we do not discuss anydetails about testing.) Since iterations form part of the detailed implementation ofphases, and are also specific to particular projects, we do not discuss the iterationcycles either. Finally, we draw some comparisons with some of the other design methodsthat we have examined in this and earlier chapters.The UP phasesThe phases are very project-driven, and create a framework that emphasizes the stronguser links and iterative practices that characterize the UP (both of which are ratherreminiscent of DSDM although, of course, DSDM does not provide any equivalents tothe workflows). The descriptions are kept fairly brief and are chiefly focused on themore technical issues rather than project-centred ones.1. Inception This phase is primarily concerned with getting a project ‘under way’,and so most of its goals are related to planning activities. These include:nnnnestablishing the feasibility of the project (possibly with the aid of one or moreexploratory prototypes);developing a business case that relates the outcomes of the project to the organization’sneeds;eliciting the essential core functional and non-functional requirements for the systemand agreeing these with the stakeholders;identifying the critical risk factors, and determining how these will be addressed inthe project.The milestone for this phase, Life Cycle Objectives, can be quantified in terms of a setof deliverables (documents, models, prototypes) that encompasses those goals, andwhich includes a candidate architecture (initial architectural design) for the system.As shown in Figure 16.16, this phase largely employs the workflow techniques ofRequirements Elicitation and Analysis (the latter largely for the purpose of establishingan initial set of use cases). The Design workflow has a relatively small, but critical,role in this phase, chiefly concerned with establishing the high-level architectural formof the system.In terms of the models produced as part of the milestone documents, this phaseshould result in:nnnan initial domain-based class modela set of domain-based use casesinitial analysis and design models