# Software Architecture Documentation (arc42) ## About this document **Purpose.** This document follows the **arc42** template to describe, communicate, and evolve the architecture of the system in a clear, lightweight, and practical way. For background on arc42, see the official overview and documentation. --- ## 1. Introduction and Goals Briefly explains why the system exists and which forces shape the architecture (business goals, functional scope, quality goals, stakeholders). **Add your content here…** ### 1.1 Requirements Overview Summarize key functional requirements or link to your product/backlog sources; keep this concise and focused on what drives architecture. **Add your content here…** ### 1.2 Quality Goals Capture 3–5 top quality attributes (e.g., performance, security, evolvability) that guide trade-offs and decisions. **Add your content here…** ### 1.3 Stakeholders List stakeholders (roles, responsibilities, concerns) whose needs the architecture must satisfy. **Add your content here…** --- ## 2. Architecture Constraints Record constraints (technical, organizational, legal, standards, runtime environments, toolchains) that restrict options and influence design. **Add your content here…** --- ## 3. System Scope and Context Defines what’s in/out of scope and how the system interacts with its environment (users, neighboring systems, external services). **Add your content here…** ### 3.1 Business Context Show business actors, interactions, and the value exchange; describe business-level inputs/outputs. **Add your content here…** ### 3.2 Technical Context Show technical interfaces, protocols, data formats, and integration endpoints between the system and external systems. **Add your content here…** --- ## 4. Solution Strategy Summarize the key architecture approach: principal patterns, frameworks, major decisions, and the rationale linked to goals and constraints. **Add your content here…** --- ## 5. Building Block View Explains the static decomposition of the system into building blocks (modules/components/subsystems), their responsibilities, and dependencies—the “floor plan”. **Add your content here…** ### 5.1 Level 1 – System/Top-Level Show the top-level breakdown into major subsystems or layers and how they collaborate. **Add your content here…** ### 5.2 Level 2 – Key Components Zoom into one or more subsystems from 5.1 and present their main components and relationships. **Add your content here…** ### 5.3 Level 3 – Internal Structure (as needed) Detail important components (data structures, classes, packages) when necessary for understanding or change. **Add your content here…** --- ## 6. Runtime View Describes significant scenarios to illustrate behavior and interactions of building blocks (sequence/flow, error paths, non-functional aspects). **Add your content here…** ### 6.x Scenario State context, triggers, participating blocks, message/interaction flow, and notable variations. **Add your content here…** --- ## 7. Deployment View Maps software artifacts to infrastructure (nodes, regions, runtime platforms), including redundancy, scaling, and operational concerns. **Add your content here…** ### 7.1 Infrastructure Overview Present environments (dev/test/stage/prod), regions/zones, and high-level topology. **Add your content here…** ### 7.2 Deployment Mapping Describe which artifacts run where; capture capacity, sizing assumptions, and elasticity. **Add your content here…** ### 7.3 Cross-Environment Differences List relevant differences (configs, data stores, integrations, security postures). **Add your content here…** --- ## 8. Cross-Cutting Concepts Central rules & approaches that apply across the system (domain model, architecture patterns, security, logging, error handling, configuration, i18n, etc.). **Add your content here…** ### 8.1 Domain & Data Share ubiquitous language, key domain concepts, data ownership, and data lifecycle. **Add your content here…** ### 8.2 Security Threat model highlights, authn/authz, secrets handling, crypto, secure defaults. **Add your content here…** ### 8.3 Observability & Operations Logging, metrics, tracing, health checks, dashboards, incident response hooks. **Add your content here…** ### 8.4 Error Handling & Resilience Policies for retries, timeouts, backoff, circuit breakers, idempotency. **Add your content here…** ### 8.5 Configuration & Feature Flags How configuration is structured, validated, and delivered; flag strategy. **Add your content here…** ### 8.6 Performance & Caching Hot paths, caching layers, data locality, performance budgets and profiles. **Add your content here…** ### 8.7 Code & API Guidelines Language/framework idioms, API style (REST/gRPC/GraphQL), versioning and compatibility rules. **Add your content here…** ### 8.8 Compliance & Data Protection Relevant standards/regulations (e.g., ISO, GDPR), data retention, audit trails. **Add your content here…** --- ## 9. Architecture Decisions A log of significant decisions (ADRs): context, options considered, decision, consequences, status (proposed/accepted/superseded). **Add your content here…** --- ## 10. Quality Requirements Elaborate quality scenarios (stimulus → response measure) tied to the goals in 1.2, including measurable acceptance criteria. **Add your content here…** ### 10.1 Quality Tree Visualize quality attributes and their refinements to orient priorities. **Add your content here…** ### 10.2 Quality Scenarios Concrete scenarios per attribute (e.g., “Under X load, 95th-pct latency ≤ Y ms”). **Add your content here…** --- ## 11. Risks and Technical Debt List key risks, assumptions, unknowns, and consciously accepted debt with mitigation/retirement plans. **Add your content here…** --- ## 12. Glossary Define important domain and technical terms to ensure a shared vocabulary; add abbreviations and acronyms. **Add your content here…** --- ## 13. Best-Practice Requirements & Quality Checklist Use these requirements to review and keep the document—and architecture—healthy over time. ### 13.1 Structural Completeness - **All 12 arc42 chapters present or explicitly marked “N/A” with rationale.** **Add your content here…** - **Each section starts with a purpose blurb and ends with concrete, current content or a tracked TODO.** **Add your content here…** - **Cross-references link related content (e.g., 4 ↔ 5/8, 1.2 ↔ 10).** **Add your content here…** ### 13.2 Consistency & Traceability - **Every major decision in 4 is backed by ADRs in 9 and aligned with 1.2/10.** **Add your content here…** - **Interfaces in 3.2 are consistent with components in 5 and scenarios in 6.** **Add your content here…** - **Deployment (7) matches runtime needs (6) and non-functional drivers (10).** **Add your content here…** ### 13.3 Quality & Measurability - **Quality goals (1.2) translated into measurable scenarios (10.2) with thresholds.** **Add your content here…** - **Operational SLOs/SLIs defined and observable (8.3) and tied to alerts/dashboards.** **Add your content here…** ### 13.4 Risk & Debt Management - **Top risks ranked with mitigations, owners, and review cadence (11).** **Add your content here…** - **Technical debt items carry impact, “pay-down” trigger, and target release.** **Add your content here…** ### 13.5 Security & Compliance Hygiene - **Threat model snapshot exists; controls mapped (8.2).** **Add your content here…** - **Data protection & retention addressed; lawful bases documented (8.8).** **Add your content here…** ### 13.6 Evolution & Maintainability - **Document is versioned; changes tracked with changelog and ADR status updates.** **Add your content here…** - **Architecture fitness checks (e.g., lightweight ATAM or quality scenario tests) scheduled.** **Add your content here…** - **Diagrams are living (source-controlled), with legend, date, and level of detail.** **Add your content here…** ### 13.7 Fitness-for-Purpose Read-Through - **One-page executive summary aligns with goals and constraints.** **Add your content here…** - **A new team member can understand system scope (3), big picture (5.1), and how to run it (7) within 60 minutes.** **Add your content here…**