Differences Between Scrum and Extreme Programming
four main differences between Scrum and XP:
Scrum teams typically work in iterations (called sprints) that are from two weeks to one month long. XP teams typically work in iterations that are one or two weeks long.
Scrum teams do not allow changes into their sprints. Once the sprint planning meeting is completed and a commitment made to delivering a set of product backlog items, that set of items remains unchanged through the end of the sprint. XP teams are much more amenable to change within their iterations. As long as the team hasn’t started work on a particular feature, a new feature of equivalent size can be swapped into the XP team’s iteration in exchange for the unstarted feature.
Extreme Programming teams work in a strict priority order.Features to be developed are prioritized by the customer (Scrum’s Product Owner) and the team is required to work on them in that order. By contrast, the Scrum product owner prioritizes the product backlog but the team determines the sequence in which they will develop the backlog items.
Scrum doesn’t prescribe any engineering practices; XP does. I love the XP engineering practices, particularly things like test-driven development, the focus on automated testing, pair programming, simple design, refactoring, and so on
Scrum and XP (aka Extreme Programming), both agile software development methodologies based on the iterative and incremental development. They do have similarities but also have differences and here is my attempt to briefly highlight the differences:
1. Scrum is more high level, focusing on the management of the project (e.g. the requirements or features are managed) rather than specifying or defining engineering practice such as pair programming or test driven development
2. The length of an iteration in XP is usually 1-3 weeks whereas, in Scrum sprints are 1-4 weeks
3. Once sprint (or iteration in XP) starts, customer cannot change the requirements, in other words the customer will have to wait until the sprint (or iteration in XP) finishes. In XP however, requirements can change anytime
4. In XP features are developed in a strict order whereas in Scrum, the team is free to choose the features to be developed. Sequence does not matter
5. Both XP and Scrum define the role of a coach, In Scrum it is called Scrum Master and requires (or strongly recommended) certification, whereas, XP defines the role of coach quite informally and the role may float between members of the team.
Scrum and XP are often used together: Scrum defines the framework and XP defines the engineering practices and they fit together nicely.
