Skip to main content

Architecture Decision Records (ADRs)

Overview​

This folder contains Architecture Decision Records (ADRs) documenting key architectural decisions made for the Inventory Management Module. Each ADR captures the context, alternatives considered, and rationale for important design choices.

What is an ADR?​

An Architecture Decision Record documents an architecturally significant decision, including:

  • Context: The issue or problem being addressed
  • Alternatives: Options considered with pros/cons
  • Decision: The chosen solution and why
  • Consequences: Expected benefits and trade-offs
  • Implementation Guidance: How to apply the decision

ADR Index​

Items Architecture​

ADR-ITEM-001: Composition Over Inheritance for Item Stockability

  • Status: Accepted
  • Date: 2024-10-15
  • Summary: Establishes composition-based design for item stockability using optional StockableBehavior value object instead of inheritance hierarchy. Enables items to transition between stockable and non-stockable states while maintaining clean aggregate boundaries.
  • Key Concepts: Composition over inheritance, optional behaviors, value objects, flexible item lifecycle

Transactions Architecture​

ADR-TRANS-001: Unified Transaction Aggregate with Type Discriminator

  • Status: Accepted
  • Date: 2024-10-18
  • Summary: Adopts single unified InventoryTransaction aggregate for all transaction types (Purchase, Sales, Movement, Adjustment, Assembly) with type discriminator enum and type-specific value objects. Enforces business rules through factory methods.
  • Key Concepts: Unified aggregate, type discriminator, compositional details, factory methods, immutability

Shared Architecture​

ADR-SHARED-001: Event-Driven Architecture for Module Integration

  • Status: Accepted
  • Date: 2024-10-20
  • Summary: Establishes event-driven integration between modules using message bus (RabbitMQ + MassTransit) rather than direct API calls or shared database. Provides loose coupling, autonomous operation, and eventual consistency.
  • Key Concepts: Integration events, message bus, eventual consistency, idempotency, loose coupling

ADR Format​

All ADRs follow a consistent structure:

---
id: ADR-{MODULE}-{NUMBER}
title: Decision Title
status: Proposed | Accepted | Deprecated | Superseded
date: YYYY-MM-DD
author: Author Name
---

### 1. Executive Summary
### 2. Context
### 3. The Architectural Debate
### 4. The Accepted Solution
### 5. Implementation Guidance
### 6. Benefits and Trade-offs
### 7. Future Enhancements (if applicable)
### 8. Final Decision

ADR Statuses​

  • Proposed: Under consideration, not yet decided
  • Accepted: Decision made and being implemented
  • Deprecated: No longer recommended, but still in use
  • Superseded: Replaced by a newer decision (reference provided)

How to Create a New ADR​

  1. Identify the Decision: Recognize an architecturally significant decision
  2. Research Alternatives: Explore different approaches with pros/cons
  3. Draft ADR: Use the template format above
  4. Review: Discuss with team and stakeholders
  5. Finalize: Update status to "Accepted" and date when decided
  6. Update Index: Add entry to this README

Architecturally Significant Decisions​

Decisions warrant an ADR when they:

  • Impact multiple parts of the system
  • Are difficult or costly to change later
  • Affect non-functional requirements (performance, scalability, security)
  • Establish patterns to be followed by the team
  • Involve significant trade-offs
  • Represent a departure from established patterns

Key Architectural Themes​

Domain-Driven Design (DDD)​

All ADRs follow DDD principles:

  • Aggregates with clear boundaries
  • Value objects for immutable concepts
  • Domain events for state changes
  • Repository pattern for persistence
  • Factory methods for complex creation

Composition Over Inheritance​

Established in ADR-ITEM-001 and followed throughout:

  • Behaviors added compositionally rather than through inheritance
  • Flexible, adaptable domain models
  • Clear separation of concerns
  • Extensibility without modification

Event-Driven Architecture​

Established in ADR-SHARED-001:

  • Domain events for internal module communication
  • Integration events for cross-module communication
  • Message bus for reliable delivery
  • Eventual consistency model

Immutability and Audit Trail​

Core principle across all decisions:

  • Transactions immutable after creation
  • Complete audit trail maintained
  • Corrections via new transactions, not modifications
  • Soft delete rather than hard delete

Domain Documentation​

Conceptual Documentation​

API Documentation​

Questions and Discussions​

For questions about architectural decisions or to propose new ADRs:

  1. Review existing ADRs to understand established patterns
  2. Discuss with team lead or architect
  3. Create proposal document following ADR format
  4. Schedule architecture review meeting
  5. Update ADR based on feedback and decision

Revision History​

This README and ADRs should be living documents, updated as:

  • New decisions are made
  • Existing decisions are revisited
  • Implementation reveals new insights
  • Business requirements evolve

Last Updated: 2024-10-24 | Total ADRs: 3