2. ATAM Conceptual Model

The Architecture Tradeoff Analysis Method (ATAM) is a facilitated, stakeholder-driven evaluation process designed to surface risks, non-risks, sensitivity points, and trade-offs in an architecture. Its value lies in creating a structured conversation that aligns technical decisions with business drivers and quality attributes.

Core Concepts

Sensitivity Points

Definition: A property of one or more components that is critical to achieving a specific quality attribute response.

Example: Queue depth is a sensitivity point. Adjusting it directly influences scalability and throughput.

Trade-offs

Definition: A property that simultaneously affects multiple quality attributes, often requiring explicit prioritization.

Example: Persistent vs. non-persistent queues impact durability, availability, and throughput—forcing a conscious trade-off among them.

Conceptual Flow

The ATAM process decouples business drivers and scenarios from the architectural plan and decisions, ensuring a traceable line of reasoning.

A more accurate flow in practice is:

Architectural Plan / Presentation

→ Architectural Approaches (candidate solutions and patterns)

→ Quality Attribute Requirements (QARs) tied to those approaches

→ Architectural Decisions made explicit and evaluated against QARs

Practitioner Advice

Phase Separation: Never run Phase 1 (eliciting drivers and scenarios) and Phase 2 (detailed analysis and trade-offs) in the same week.

Allow 1–2 weeks between phases for participants to reflect, refine scenarios, and prepare.

This gap leads to sharper analysis and more meaningful stakeholder engagement.

Why It Matters for Architects

Brings clarity and rigor to architectural decisions by making implicit trade-offs explicit.

Provides a shared vocabulary for stakeholders and technologists to discuss quality attributes (scalability, availability, performance, etc.).

Ensures that architecture is justified by business drivers, not just technical preference.

See Conceptual Model here: http://www.sei.cmu.edu/architecture/tools/evaluate/atam.cfm