1. Introduction to Scrum
Scrum is an iterative and incremental agile software development method for managing software projects and product or application development. Scrum enables the creation of self-organizing teams by encouraging co-location of all team members, and verbal communication among all team members and disciplines in the project. Three distinct roles are identified within the Scrum methodology:
- The Scrum master, who ensures the process is followed, removes impediments, and protects the Development Team from disruption.
- The Product Owner, who represents the stakeholders and the business.
- The Development Team, a cross-functional, self-organizing team who do the actual analysis, design, implementation, testing, and so on.
The development cycle of a software project is broken into time boxed units that are called Sprints. A common time frame for one Sprint is one week. Every day within a Sprint, the progress of the project is evaluated.
Requirements of the final product are maintained in a list called the backlog (product backlog). In each Sprint, one or more requirements will be implemented (Sprint backlog) after which the next Sprint is started.
2. Roles
2.1 Scrum Master
Scrum is facilitated by a Scrum Master, sometimes written as ScrumMaster, who is accountable for removing impediments to the ability of the team to deliver the Sprint goal/deliverables. The Scrum Master is not the team leader, but acts as a buffer between the team and any distracting influences. The Scrum Master ensures that the Scrum process is used as intended. The Scrum Master is the enforcer of rules. A key part of the Scrum Master’s role is to protect the Development Team and keep it focused on the tasks at hand.
2.2 Product Owner
The Product Owner represents the voice of the customer and is accountable for ensuring that the team delivers value to the business. The Product Owner writes customer-centric items (typically user stories), prioritizes them, and adds them to the product backlog. Scrum teams should have one Product Owner, and while they may also be a member of the development team, it is recommended that this role not be combined with that of the Scrum Master.
The Development Team is responsible for delivering potentially shippable product increments at the end of each Sprint. A Development Team is compsoed of people with cross-functional skills who do the actual work (analysis, design, develop, test, technical communication, document, and so on). The Development Team in Scrum is self-organizing.
3. Sprint
A Sprint is the basic unit of development in Scrum. Sprints last between one week and one month, and are a “time boxed” (in other words restricted to a specific duration) effort of a constant length.
Each Sprint is preceded by a planning meeting, where the tasks for the Sprint are identified and an estimated commitment for the Sprint goal is made and followed by a review or retrospective meeting, where the progress is reviewed and lessons for the next Sprint are identified.
During each Sprint, the team creates finished portions of a product. The set of features that go into a Sprint come from the product backlog, that is a prioritized list of requirements. 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 ones with the highest priority). The team then determines how much of this they can commit to complete during the next Sprint, and records this in the Sprint backlog. During a Sprint, no one is allowed to change the Sprint backlog. That means that the requirements are frozen for that Sprint. The development is time boxed such that the Sprint must end on time; if requirements are not completed for any reason then they are left out and returned to the product backlog. After a Sprint is completed, the team demonstrates how to use the software.
Scrum enables the creation of self-organizing teams by encouraging co-location of all team members, and verbal communication among all team members and disciplines 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.
4. Meetings
4.1 Daily Scrum
Each day during the Sprint, a project status meeting occurs. This is called a daily scrum, or the daily standup. This meeting has the following specific guidelines:
- The meeting starts precisely on time.
- All are welcome, but normally only the core roles speak.
- The meeting length is set (timeboxed) to 15 minutes.
- The meeting should happen at the same location and same time every day.
During the meeting, each team member answers three questions:
- What have you done since yesterday?
- What are you planning to do today?
- Any impediments/stumbling blocks?
It is the role of the Scrum Master to facilitate resolution of these impediments, although the resolution should occur outside the Daily Scrum itself to keep it as short as possible.
4.2 Sprint Planning Meeting
At the beginning of a Sprint, a “Sprint planning meeting” is held.
- Select what work is to be done
- Prepare the Sprint Backlog that details the time it will take to do that work, with the entire team
- Identify and communicate how much of the work is likely to be done during the current Sprint
The team should spend time during a Sprint doing backlog grooming. This is the process of: estimating the existing backlog using effort/points, refining the acceptance criteria for individual stories, and breaking larger stories into smaller stories.
- Meetings should not be longer than an hour
- A meeting does not include breaking stories into tasks
- The team can decide how many meetings are needed per week.
4.3 Sprint Review Meeting
- Review the work that was completed and not completed
- Present the completed work to the stakeholders (a.k.a. “the demo”)
4.4 Sprint Retrospective
- All team members reflect on the past Sprint
- Make continuous process improvements
- Two main questions are asked in the Sprint retrospective: What went well during the Sprint? What could be improved in the next Sprint?
4.5 Scrum of Scrums
Each day normally after the Daily Scrum.
These meetings allow clusters of teams to discuss their work, focusing especially on areas of overlap and integration.
- A designated person from each team attends.
- The agenda will be the same as the Daily Scrum, plus the following four questions.
- What has your team done since we last met?
- What will your team do before we meet again?
- Is anything slowing your team down or getting in their way?
- Are you about to put something in another team’s way?
5. Tools
A Team Foundation System has integrated scrum support. With the Microsoft Visual Studio Scrum 1.0 template, it is possible to maintain a product backlog, scope the Sprints, define tasks, assign tasks and create several reports to monitor the progress of the Sprint and the project.
The Scrum tools in TFS can either be accessed from Visual Studio or by using a web interface. The latter is useful for testers and project managers who do not have access to Visual Studio. Furthermore, the web interface exposes some batch processing commands not available in Visual Studio.
6. Conclusion
Scrum is a suitable method to support the development process. It is very efficient in creating solutions with the highest business value in the shortest possible time. Due to the daily scrums any impediments are known to everyone as they occur making it possible to resolve them as quickly as possible. Furthermore, it adds support to prioritize work and closely monitor the progress of a project with little to no overhead.
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