A design decision is a chosen resolution to a software design problem or alternative. Design activities move a team from the problem space toward a preferred software system, and their resulting plans formulate design decisions. section 3.1.3
Design decisions may remain implicit, isolated, or based on incorrect models. Making them explicit through collaborative modeling helps teams expose assumptions, share understanding, compare tradeoffs, and reduce ambiguity. section 3.1 section 3.1.5
Assess a design decision by asking:
- Does it alter the foundational shape of the software system, or merely change an isolated part of the code? section 3.1.3
- Have the relevant domain experts and stakeholders identified its alternatives, tradeoffs, and value? section 3.1.5
- Can everyone understand and communicate the decision, including its effects on technical, social, and organizational concerns? section 1.3 section 3.1.5
BigScreen’s reservation system
During EventStorming, the BigScreen team examined its ticket-purchasing process for an “Anytime, Anywhere” campaign. The exercise revealed how the existing system had evolved and surfaced surprising past decisions. When teams are excluded from such decisions, they may implement conflicting designs, causing delays, rework, and an implicit architecture. section 3.1.2 section 3.1.5
