Core Idea
Architecture decision criteria are the evaluation factors used to systematically choose an architecture style based on ranked architecture characteristics, business drivers, constraints, and trade-off analysis rather than trends or personal preference.
Architecture Decision Criteria
The Common Trap: Making architecture decisions based on what’s popular or what you’ve used before is a common but dangerous trap. Effective architecture decision criteria provide a structured framework for evaluating and selecting architecture styles that genuinely fit your context.
Starting Point - Identify Architecture Characteristics:
- Identify your architecture characteristics from both:
- Explicit requirements: Stated by stakeholders
- Implicit needs: Derived from domain and organizational context
- However, identification alone isn’t sufficient
- Not all characteristics are equally important
- Attempting to optimize for everything leads to analysis paralysis and least-worst compromises
Ranking Process - Deliberate Prioritization:
- Rank characteristics as:
- Tier-1: Must-have
- Tier-2: Important
- Tier-3: Nice-to-have
- This ranking provides the foundation for evaluating architecture styles
Architecture Style Trade-offs: Each architecture style excels at supporting specific characteristics while performing poorly at others:
- Layered architecture: Excellent simplicity and low cost but poor scalability and elasticity
- Event-driven architecture: Excels at scalability and fault tolerance but introduces complexity and eventual consistency challenges
- Microservices architecture: Maximizes deployability and testability but increases operational complexity and network latency
Evaluation Framework: With ranked characteristics established, the decision criteria framework evaluates each candidate style:
- Which styles best support your tier-1 characteristics?
- For the top candidates, what trade-offs do you accept in tier-2 and tier-3 characteristics?
- This systematic evaluation surfaces the genuine costs and benefits rather than relying on intuition or marketing materials
Final Criterion - Business Alignment: The selected style must support not just technical characteristics but also organizational realities:
- Team structure
- Deployment capabilities
- Operational maturity
- Budget constraints
- Timeline pressures
- An architecture that’s theoretically optimal but incompatible with organizational capabilities will fail in practice
Why This Matters
Problems Without Explicit Criteria: Without explicit decision criteria, architects choose styles based on familiarity, trends, or vendor marketing rather than business needs:
- Leads to architectures that solve yesterday’s problems or someone else’s problems
- Rather than solving your actual requirements
Benefits of Systematic Criteria: Systematic criteria transform architecture selection from art to engineering:
- Makes decisions defensible
- Makes decisions repeatable
- Aligns decisions with business drivers
Related Concepts
- Architecture-Characteristics-Categories — The operational, structural, and cross-cutting characteristics being evaluated
- Explicit-Architecture-Characteristics — Tier-1 characteristics stated by stakeholders
- Implicit-Architecture-Characteristics — Hidden characteristics derived from domain
- Architecture-Style-Selection-Framework — The systematic process using these criteria
- Trade-Offs-and-Least-Worst-Architecture — The fundamental reality of architecture decisions
- Architecturally-Significant-Decisions — Decisions that require this level of rigor
- Architecture-Decision-Records — Documentation capturing the criteria and rationale
Sources
- Richards, Mark and Neal Ford (2020). Fundamentals of Software Architecture: An Engineering Approach. O’Reilly Media. ISBN: 978-1-492-04345-4.
- Chapter 18: Choosing the Appropriate Architecture Style
- Available: https://www.oreilly.com/library/view/fundamentals-of-software/9781492043447/
Note
This content was drafted with assistance from AI tools for research, organization, and initial content generation. All final content has been reviewed, fact-checked, and edited by the author to ensure accuracy and alignment with the author’s intentions and perspective.