Evolutionary Delivery versus the "waterfall model"

Abstract

The conventional wisdom of planning software engineering projects, using the widely cited "waterfall model" is not the only useful software development process model. In fact, the "waterfall model" may be unrealistic, and dangerous to the primary objectives of any software project.The alternative model, which I choose to call "evolutionary delivery" is not widely taught or practiced yet. But there is already more than a decade of practical experience in using it. In various forms. It is quite clear from these experiences that evolutionary delivery is a powerful general tool for both software development and associated systems development.Almost all experienced software developers do make use of some of the ideas in evolutionary development at one time or another. But, this is often unplanned, informal and it is an incomplete exploitation of this powerful method. This paper will try to expose the theoretical and practical aspects of the method in a fuller perspective. We need to learn the theory fully, so that we can apply and learn it completely.

Historical Roots of Agile Methods: Where Did “Agile Thinking” Come From?

“…Gilb based EVO on three simple principles [17]: • Deliver something to the real end-user • Measure the added-value to the user in all critical dimensions • Adjust both design and objectives based on observed realities…”

“…When he discussed the early frequent iteration, he emphasised the concept of selecting the "potential steps with the highest user-value to developmentcost ratio for earliest implementation" [17]. Another important concept in EVO method is "Complete analysis, design and test in each step" where he stated that the waterfall is one of the great time wasters with too many unknowns, too much dynamic change and systems complexity.…”

“…EVO first principle: deliver something to the real end-user [17] Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage.…”

“…In EVO the frequent and early delivery is essential , also RAD recommended quick delivery [17,24] Business people and developers must work together daily throughout the project.…”

“…EVO second principle: measure the addedvalue to the user in all criteria dimensions [17] Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.…”