Scrum is an iterative incremental framework for managing complex work (such as new product development) commonly used with agile software development. Although the word is not an acronym, some companies implementing the process have been known to spell it with capital letters as SCRUM. This may be due to one of Ken Schwaber’s early papers, which capitalized SCRUM in the title.
Although Scrum was intended for management of software development projects, it can be used to run software maintenance teams, or as a general project/program management approach.
Scrum is a “process skeleton,” which contains sets of practices and predefined roles. The main roles in Scrum are:
the “ScrumMaster”, who maintains the processes (typically in lieu of a project manager); the “Product Owner”, who represents the stakeholders; the “Team”, a cross-functional group of about 7 people who do the actual analysis, design, implementation, testing, etc. During each “sprint”, typically a two to four week period (with the length being decided by the team), the team creates a potentially shippable product increment (for example, working and tested software). The set of features that go into a sprint come from the product “backlog,” which is a prioritized set of high level requirements of work to be done. Which backlog items go into the sprint is determined during the sprint planning meeting. During this meeting, the Product Owner informs the team of the items in the product backlog that he or she wants completed. The team then determines how much of this they can commit to complete during the next sprint. During a sprint, no one is allowed to change the sprint backlog, which means that the requirements are frozen for that sprint. After a sprint is completed, the team demonstrates the use of the software.
Scrum enables the creation of self-organizing teams by encouraging co-location of all team members, and verbal communication across all team members and disciplines that are involved in the project.
A key principle of Scrum is its recognition that during a project the customers can change their minds about what they want and need (often called requirements churn), and that unpredicted challenges cannot be easily addressed in a traditional predictive or planned manner. As such, Scrum adopts an empirical approach—accepting that the problem cannot be fully understood or defined, focusing instead on maximizing the team’s ability to deliver quickly and respond to emerging requirements.
There are several implementations of systems for managing the Scrum process, which range from yellow stickers and whiteboards, to software packages. One of Scrum’s biggest advantages is that it is very easy to learn and requires little effort to start using.
Ken Schwaber (below) co-developed the Agile process, Scrum. He is a founder of the Agile Alliance and Scrum Alliance, and signatory to the Agile Manifesto. Ken has been a software developer for over thirty years. He is an active advocate and evangelist for Agile processes.
In 1986, Hirotaka Takeuchi and Ikujiro Nonaka described a new holistic approach that increases speed and flexibility in commercial new product development. They compare this new holistic approach, in which the phases strongly overlap and the whole process is performed by one cross-functional team across the different phases, to rugby, where the whole team “tries to go to the distance as a unit, passing the ball back and forth”. The case studies come from the automotive, photo machine, computer and printer industries.
In 1991, DeGrace and Stahl, in Wicked Problems, Righteous Solutions, referred to this approach as Scrum, a rugby term mentioned in the article by Takeuchi and Nonaka. In the early 1990s, Ken Schwaber used an approach that led to Scrum at his company, Advanced Development Methods. At the same time, Jeff Sutherland, John Scumniotales, and Jeff McKenna developed a similar approach at Easel Corporation and were the first to call it Scrum. In 1995 Sutherland and Schwaber jointly presented a paper describing Scrum at OOPSLA ’95 in Austin, TX, its first public appearance. Schwaber and Sutherland collaborated during the following years to merge the above writings, their experiences, and industry best practices into what is now known as Scrum. In 2001, Schwaber teamed up with Mike Beedle to describe the method in the book Agile Software Development with Scrum.
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