Evolutionary Software Development(ESD) Premkumar

The Requirements Paradox Requirements must be stable Requirements always change Use a process that can cope with the Requirements paradox You cannot foresee every change but you can forsee change itself

2 nd Requirements Paradox We don’t want requirements to change Because requirements change is a known risk: We must provoke requirements change as early as possible !!

ESD? ESD or Evolutionary Software development is a software lifecycle model,which structures and guides the activities between the initial idea of a product and its final implementation. In this approach the developmental cycle is divided smaller incremental cycles in which the users are able to get access to the product at the end of each cycle.

Alright,but why ESD? To understand why let’s first figure out the traditional and most prominent lifecycle model, the WATERFALL MODEL In this model, the development process is organized as a series of steps from the initial software concept,requirements analysis, etc through implementation and testing. Each phase is separated, reviews are held at the end of each phase to determine whether the next phase of the project can be given the go ahead. However applying the Waterfall model requires a correct and complete understanding of the requirements from the beginning.

How they Compare Software development life cycles a) Waterfall model b) Evolutionary model

..contd The Waterfall Model

.contd The Evolutionary Model

Where ESD scores over Waterfall It addresses the ever present problem of change in requirements by early and ongoing involvement of the user in the development process. Increases visibilty of the management by breaking the project into smaller,more manageable pieces,thus addressing any potential risks effectively Continuous process improvement becomes a more realistic possibility The ability of developers to respond to market changes is increased in ESD because the software is continuously evolving and the development team is thus better positioned to change a feature set or release it earlier.

What does an ESD modelled project demand? Clear vision Project planning Select manage users Shift management focus Manage builds

When is ESD not required? When requirements are completely clear, nothing will change :: use waterfall Requirements can easily be met with the available resources, within the available time Everybody knows exactly what to do People make no mistakes Customer can wait until you are ready

Conclusion The most salient and consistent benefits of the ESD model have been its ability to get early,accurate well formed feedback from users and the ability to respond to that feedback. Additional advantages have come from the ability to Better fit the product to user needs and market requirements Manage project risk with definition of early cycle content Uncover key issues early and focus attention appropriately Increase the opportunity to hit market windows Accelerate sales cycles with early customer exposure Increase management visibility of project progress Increase product team productivity and motivation.

..Contd major changes in the customer-developer relationship can result in customer demand for more input and involvement in product definition and design. Since many software developers are no longer primary users of their products, they now need to be able to understand the Primary users’ needs, skill levels, and motivations. Numerous organisations worldwide have recognised ESD for its benefits and have been adopting it with great success..

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