Software Engineering

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CHAPTER 4 
Understanding the Software Project Environment
completion date and deadline that identifies when a delay in task completion begins 
to affect other tasks.
The most common technique for defining a WBS is to use the product break-
down structure to identify the effort necessary to define, design, implement, and 
test the various parts of the product, and perform assembly, integration, and test-
ing of components. This permits each of the project organizations to identify the 
work associated with each element of the software product, identify the staff work 
assignments, and ensure that staff skills and expertise are properly applied across 
all work products. Each work package should be assigned a work authorization or 
cost accounting control number used to track cost accrual over time.
The work package definition establishes the dependencies among task execu-
tion that provide the information necessary to construct a work plan, schedule, and 
budget. The work plan should identify the activities and tasks that must be accom-
plished to generate work products, the organizational roles and contribution to each 
task, and the level of effort and resources necessary to perform the identified work. 
Risks to task execution should be identified and incorporated into the work plan and 
schedule to identify potential problematic situations that must be monitored, and 
the anticipated response to adverse occurrences.
The WBS has long been a project management tool used to define, organize, 
and track progress toward achieving project objectives. It captures the work to be 
performed necessary to deliver the software product and establish the post-devel-
opment processes. It illustrates the numerous interactions among the software 
development organizations required to coordinate and collaborate on development 
activities. However, a new software development product cannot be defined in 
terms of its product breakdown structure during the early stages of development. 
Therefore, the work packages and cost allocations must be continually revisited and 
elaborated to reflect the software architecture as it evolves.
The WBS provides an excellent gage of the project and product complexity rela-
tionships. The number of dependencies among tasks provides a basis for establish-
ing a critical path for achieving project objectives. The slack time (time between 
planned completion and deadline) indicates how compressed the work plan has 
been constructed. The smaller the slack time between elements on the critical path 
indicates the relative stress and significance the tasks on the critical path are to be 
accomplished according to the plan. Slack time should be built into the schedule’s 
critical path to account for unforeseen events that may cause tasks to be delayed.