Crystal

Crystal methods are a family of methodologies (the Crystal family) that were developed by Alistair Cockburn in the mid-1990s. The methods come from years of study and interviews of teams by Cockburn. Cockburn’s research showed that the teams he interviewed did not follow the formal methodologies yet they still delivered successful projects. The Crystal family is Cockburn’s way of cataloging what they did that made the projects successful.

Crystal methods are considered and described as “lightweight methodologies”. The use of the word Crystal comes from the gemstone where, in software terms, the faces are a different view on the “underlying core” of principles and values. The faces are a representation of techniques, tools, standards, and roles.

Methodology, techniques, and policies are differentiated between by Cockburn:

• Methodology – set of elements (e.g. practices, tools)
• Techniques – skill areas (e.g. developing use cases)
• Policies – dictate organizational musts

Crystal methods are focused on:

• People
• Interaction
• Community
• Skills
• Talents
• Communications

Cockburn says that Process, while important, should be considered after the above as a secondary focus. The idea behind the Crystal Methods is that the teams involved in developing software would typically have varied skill and talent sets and so the Process element isn’t a major factor.

Since teams can go about similar tasks in different ways, the Crystal family of methodologies are very tolerant to this which makes the Crystal family one of the easiest agile methodologies to apply.

In his research, Cockburn [1999], he defines behaviour of people in teams:

• “People are communicating beings, doing best face-to-face, in person, with real-time question and answer.”
• “People have trouble acting consistently over time.”
• “People are highly variable, varying from day to day and place to place.”
• “People generally want to be good citizens, are good at looking around, taking initiative, and doing ‘whatever is needed’ to get the project to work.”

The points above are why Crystal methods are so flexible and why they avoid strict and rigid processes typically found in older methodologies.

Regardless of which Crystal implementation you choose, you will find seven key principles at the heart of each:

• Frequent Delivery: Project owners/customers can expect deliverables from the team(s) every couple of months.
• Continual Feedback: The entire project team meets on a regular basis to discuss project activities.
• Constant Communication: Small projects expect the entire team to be in the same room, while larger projects are expected to be co-located in the same facility.
• Safety: Crystal is somewhat unique in its focus on the safety aspect of software development.
• Focus: Team members are expected to know the top two or three priority items each member should be working on and should be given time to complete them without interruption.
• Access to Users: As with most Agile methods, Crystal expects that the project team will have access to one or more users of the system being built.
• Automated Tests and Integration: Crystal has various capacities for verification of project functionality.

The Crystal Family

Cockburn developed the different methods in the family of methodologies to suit teams of different sizes which need different strategies to solve diverse problems.

The Crystal family of methodologies use different colours to denote the “weight” of which methodology to use. If a project were a small one a methodology such as Crystal Clear, Crystal Orange or Crystal Yellow may be used or if the project was a mission-critical one where human life could be endangered then the methods Crystal Diamond or Crystal Sapphire would be used.

The letters in the cells represent the criticality of the project as follows:

• C: Comfort
• D: Discretionary Money
• E: Essential Money
• L: Life

The numbers in the cells represent the upper size of the project team. For teams up to six, the Crystal Clear methodology works fine. For teams of seven to 20, Crystal Yellow will introduce mechanisms to help manage the additional team size.