Sometimes a design only seems good because there isn’t a baseline for comparison. With the sketch and compare activity, we create two or more alternatives of the same design so it’s easier to see the pros and cons.

Any design alternatives can be sketched and compared. This includes current and future, ideal and reality, technology A and technology B, and many others. Sketching the extremes can also be compared. To do this, pick a quality attribute or design concept and design the architecture for that one thing at the exclusion of all else. Then pick another high-priority quality attribute or interesting design concept and sketch an alternative design for comparison.

Benefits

• Expose both the positive and negative aspects of a decision by comparing it to something else.

• Create a platform for discussion and build consensus around a design decision.

• Avoid buyer’s remorse when making a design decision by doing at least a basic comparison.

Activity Timing

20--30 minutes, up to an hour

Participants

This activity works best in small groups of 3--5 people, including the architect and other stakeholders.

Preparation and Materials

• Whiteboard or flipchart, markers
• Alternatively, prepared views (for example, in slide software), projector

Steps

1. Establish the goals of the activity by saying something like, It seems like there are at least two alternative designs on the table. Let’s put them side by side and pick one.

2. Sketch or show the alternative designs so everyone can see them.

3. Open the discussion by pointing out an advantage or disadvantage of one design compared to the other. Invite others to share their thoughts.

4. Write down participants’ ideas as they share them. If necessary, change or annotate the diagrams to clarify meaning or add new insights.

5. As the group begins to reach consensus, summarize the decisions made. Give a just-in-time sanity check (introduced) to verify that participants understand and agree with the decisions.

6. Take pictures, record the decisions in your team wiki, and use the discussion to help flesh out design rationale.

Guidelines and Hints

• Help participants avoid argumentative confrontations and encourage constructive participation. Sometimes participants will pick sides and entrench themselves, strongly favoring one design over the other.

• Be ready to sketch compromises as the discussion progresses. Some of these new ideas will become new design alternatives.

• Always summarize the findings. Skipping the final summary can leave participants confused about the decisions made.

• Follow up with skeptics to win them over and drive consensus.

Example

In this example, the team was struggling with a few ideas. Parts of the software system were undergoing major refactoring and the team had a strong desire to avoid rework if possible. Several new responsibilities needed a home and two alternatives had been proposed. A deadline was looming and a decision had to be made with imperfect information.

In this case, the team sketched diagrams of the current and possible future designs. Some team members were not satisfied with the current architecture. After seeing how it compared to the potential future state, they were much more willing to go along with the current design. The discussion that went with these sketches also created a shared understanding for the future direction of the system and identified areas with potential technical debt.