This article was originally published on bmf-tech.com.
When making technology selections and design decisions, it is extremely important to explicitly state the constraints and trade-offs involved.
Decision making is always the act of choosing the best option from multiple choices under limited conditions. Therefore, unless the premises and limitations under which the decision was made are documented, it becomes difficult to understand "why this choice was made" when looking back later.
Clarifying the Premises of Decision Making
Technical decisions are made based on "the situation at that time," "the given constraints," and "the evaluation criteria adopted." If these premises are left ambiguous and only the options are recorded, it becomes unclear "why this choice was made," making re-evaluation difficult.
For example, if the background is made clear, it creates a sense of understanding regarding the following question:
Example: "Why was a monolith adopted instead of microservices?"
→ "Because it was in the early development stage, and the team size and resources were limited. There was a need to prioritize speed and avoid the complexity of deployment and operations."
In this way, if the constraints and evaluation criteria are made explicit, the rationality of the decision can be explained.
Future Decision-Making Material
As time passes, organizational structures, technological environments, and requirements change. As a result, decisions that were once optimal may no longer be valid at the present time.
If the trade-offs that existed in past decisions are recorded, it becomes easier to re-evaluate whether "we should take a different option now."
Example: "At that time, we prioritized performance requirements and adopted an in-memory configuration, but now scalability is an issue, and we should transition to a distributed cache."
Such discussions cannot occur without records.
Recognizing and Discussing Technical Debt
Recording trade-offs is also the act of making the implicit debt an "intentional choice."
This involves sharing with the team or organization "where the limitations were placed" and "where compromises were made," which is also helpful for future refactoring and improvement planning.
It is, in a sense, "visualizing the repayment plan."
Facilitating Consensus and Education Within the Team
If constraints and trade-offs are recorded, the cost of explaining to new team members or other departments "why this technology was adopted" and "why this configuration exists" decreases.
Moreover, the process of creating records allows for aligning perceptions among stakeholders, facilitating consensus building.
Verbalizing trade-offs enhances the transparency of decisions and fosters a design culture.
What to Record
By describing from the following perspectives, it becomes a reusable and explanatory record of decision making.
| Item | Content |
|---|---|
| Constraints | Technical limitations, organizational circumstances, external requirements, etc. (e.g., tool selection, availability of skills, implementation deadlines, etc.) |
| Trade-offs | Reasons for not choosing other options, what was prioritized and what was sacrificed (e.g., choosing operational simplicity over flexibility) |
| Side Effects | Unintended but possible impacts (e.g., increased learning costs, effects on runtime performance, etc.) |
If such information is available, the decision itself can be treated as "re-evaluable knowledge."
Conclusion: Reasons for Documenting Constraints and Trade-offs
- To clarify the background of decisions and leave a record that can withstand future re-evaluation.
- To make decisions not just transient choices but something that can be shared and utilized as organizational knowledge.
Making constraints and trade-offs explicit is not just about creating design documents; it is the foundation for continuously evolving the organization’s technical decision-making.
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