For understanding the further differences between the two, it is important that we know what Agile Development is. The Agile manifest defines the agile methodology. There are 7 agile methodologies; namely XP, Crystal orange, Scrum, Adaptive Software Development, DSDM, Pragmatic programming and Feature – driven development. All these methods differ in their mechanisms and the parameters they take. All these methods have a different agile life cycle. For ASD, it depends on what techniques we are going to use. Generally speaking it doesn’t have a life cycle of its own. In contrast to this, scrum has an abstract lifecycle which packs certain activities in to its schedule.
However here we discuss differences based up on a lifecycle having some general phases.
- Project initiation: This step includes justification of the project and determining the requirements.
- Planning: Laying out an elaborate plan for development and leaving some gap for contingency actions. Scrum doesn’t have choice for including optional phases. It must work within predefined options, whereas the adaptive software development can have many options because it does not limits itself to few techniques.
- Elaboration of requirements: This stage is optional. The requirements are explained in great detail. Scrum does not implement this stage separately, but, it may be done in Adaptive Software development. Since the requirements are still in high level, they need to be broken down in to simpler specifications. The requirements are collated in to requirements document after classification. This document also contains use cases apart from the requirements.
- Architecture: Both scrum and ASD are based on agile principle of, design today and refactor tomorrow. Software developed using ASD can be modified to suit the changing environment just by adjusting their software capabilities and leaving the hardware unchanged. Software developed through scrum has to be modified through manual intervention and may even require to change hardware. A system architecture document is prepared in this phase.
- Release: The software is released to the customer. It has one timebox at least. Scrum can have many releases depending upon the development span of the project. Adaptive software usually delivers product in one go.
One of the important questions to be asked during project initiation phase is that whether to invest more or not? Not all methods answer this question. However addressing this question is an important part of the adaptive software development. Scrum doesn’t address this question explicitly. Next step is choosing the appropriate method. Scrum claims that it can be used for any project. Adaptive software development creates a list of all alternatives that can be used and chooses the best one.
The level of formality to be maintained in scrum is given by documents such as running code and backlog. In adaptive software development there are many too many choices to choose from. It makes use of vision statements for clearing out the confusion. Scrum defines a sprint goal which is a kind of timebox vision i.e., it follows one choice for some time and then can change if required.
Scrum avoids elaboration phase for speeding up the delivery. It uses product backlog maintained by the product owner.
Since adaptive software development may have an elaboration phase, it may also have a draft plan initially which may turn into a complete plan after determination of requirements. Scrum plans based on timeboxes.
Both methodologies help you work faster creating products with better quality. The agile customer too is an important role in the agile process. The customers are responsible for providing input during prototyping sessions. The organizing and controlling of user testing is the responsibility of the user.