Software Engineering Lec#8

Plan-driven and agile development
? Agile approaches to software development consider design and implementation to be the central activities in the software process. They incorporate other activities, such as requirements elicitation استنباط/توضيح and testing, into design and implementation. By contrast, a plan-driven approach to software engineering identifies separate stages in the software process with outputs associated with each stage. The outputs from one stage are used as a basis for planning the following process activity. Figure below shows the distinctions between plan-driven and agile approaches to system specification. In a plan-driven approach, iteration occurs within activities with formal documents (Every project manager should create a small core set of formal documents defining the project objectives, how they are to be achieved, who is going to achieve them, when they are going to be achieved, and how much they are going to cost. These documents may also reveal inconsistencies that are otherwise hard to see) used to communicate between stages of the process. For example, the requirements will evolve تطور and, ultimately, a requirements specification will be produced. This is then an input to the design and implementation process. In an agile approach, iteration occurs across activities. Therefore, the requirements and the design are developed together, rather than separately. A plan-driven software process not necessarily waterfall model – plan-driven, incremental development and delivery is possible. It is perfectly feasible to allocate requirements and plan the design and development phase as a series of increments. An agile process is not inevitably code-focused and it may produce some design documentation.