Roles in XP

XP defines the following roles for a software development process [Beck2000].

• Programmer The programmer writes source code for the software system under development. This role is at the technical heart of every XP project because it is responsible for the main outcome of the project: the application system.

• Customer The customer writes user stories, which tell the programmer what to program. "The programmer knows how to program. The customer knows what to program" [Beck2000].

• Tester The tester is responsible for helping customers select and write functional tests. On the other side, the tester runs all the tests again and again to create an updated picture of the project state.

• Tracker The tracker keeps track of all the numbers in a project. This role is familiar with the estimation reliability of the team. Whoever plays this role knows the facts and records of the project and should be able to tell the team whether they will finish the next iteration as planned.

• Coach The coach is responsible for the development process as a whole. The coach notices when the team is getting "off track" and puts it "back on track." To do this, the coach must have a profound knowledge of and experience with XP.

• Consultant Whenever the XP team needs additional special knowledge, they "hire" a consultant who possesses this knowledge. The consultant transfers this knowledge to the team members, enabling the team to solve the problem on their own.

• Big boss The big boss is the manager of the XP project and provides the resources for it. The big boss needs to have the general picture of the project, be familiar with the current project state, and know whether any interventions are needed to ensure the project's success.

Although XP addresses management of the software development aspects with the big boss role, it neglects the equivalent of this role on the customer side. XP merges all customer roles into the customer role. We suggest splitting the customer role into two roles: user and client.