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CHAPTER 7  PROJECT SCHEDULING AND TRACKING                         181

                          I.1                 I.3a                     I.5a
                        Concept              Tech. risk               Concept
                         scoping            assessment               implement.


                                   I.2         I.3b         I.4        I.5b
                                 Concept     Tech.Risk    Proof of    Concept     Integrate
                                 planning   assessment    concept    implement.    a, b, c


                                              I.3c                     I.5c                 I.6
                                             Tech. risk               Concept            Customer
                                            assessment               implement.           reaction
                                                                   Three I.5 tasks are
                                                                   applied in parallel to
                                                                   3 different concept
                                                                   functions
               FIGURE 7.3 A task network for concept development

                              as a whole is to be completed on schedule. These issues are discussed in more detail
                              later in this chapter.
                                It is important to note that the task network shown in Figure 7.3 is macroscopic.
                              In a detailed task network (a precursor to a detailed schedule), each activity shown
                              in Figure 7.3 would be expanded. For example, Task I.1 would be expanded to show
                              all tasks detailed in the refinement of Tasks I.1 shown in Section 7.5.


                        7.7   SCHEDULING

                              Scheduling of a software project does not differ greatly from scheduling of any multi-
                              task engineering effort. Therefore, generalized project scheduling tools and tech-
                For all but the simplest  niques can be applied with little modification to software projects.
                projects, scheduling
                should be done with  Program evaluation and review technique (PERT) and critical path method (CPM)
                the aid of a project  [MOD83] are two project scheduling methods that can be applied to software devel-
                scheduling tool.  opment. Both techniques are driven by information already developed in earlier proj-
                              ect planning activities:
                                •  Estimates of effort
                                •  A decomposition of the product function

                                •  The selection of the appropriate process model and task set
                                •  Decomposition of tasks
                              Interdependencies among tasks may be defined using a task network. Tasks,  some-
                              times called the project work breakdown structure (WBS), are defined for the product
                              as a whole or for individual functions.
                                Both PERT and CPM provide quantitative tools that allow the software planner to
                              (1) determine the critical path—the chain of tasks that determines the duration of the
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