4. Solution Strategy

This section outlines the key architectural strategies and technology decisions for BookWorm.
It provides a high-level overview of the solution architecture, technology stack, deployment strategy, and quality assurance practices.

4.1 Technology Decisions

Core Technology Stack

Technology	Decision Rationale	ADR
.NET Aspire	Provides cloud-native development framework with built-in observability, service discovery, and configuration management	ADR-003
Domain-Driven Design	Ensures business logic clarity and maintainable service boundaries aligned with business domains	ADR-001
Vertical Slice Architecture	Organizes code by feature rather than layer, improving maintainability and team autonomy	-
Event-Driven Architecture	Enables loose coupling, scalability, and eventual consistency across microservices	ADR-002

Data Storage Strategy

Storage Type	Technology	Use Case	ADR
Primary Database	PostgreSQL	All transactional data with ACID properties	ADR-004
Cache Layer	Redis	Session storage, caching, and performance optimization	ADR-004
Event Store	PostgreSQL	Event sourcing for domain events	ADR-002

4.2 Architectural Patterns

Microservices Architecture

Event-Driven Communication

Saga Patterns

Orchestration Saga: Used for complex business processes requiring centralized control

• Order processing workflow
• Compensation handling for failed transactions

Choreography Saga: Used for loosely coupled domain interactions

• Catalog updates triggering search index refresh
• User actions generating analytics events
• Cross-domain notifications

Event Patterns

Pattern	Implementation	Use Case
Outbox Pattern	Database transaction + event publishing	Ensuring reliable event publishing
Inbox Pattern	Idempotent event processing	Preventing duplicate event handling
Event Sourcing	Domain events as source of truth	Audit trail and temporal queries
CQRS	Separate read/write models	Optimized queries and command processing

4.3 Quality Assurance Strategy

Testing Strategy

Quality Attributes Implementation

Quality Attribute	Implementation Strategy
Scalability	Horizontal scaling with container orchestration, stateless services, async processing
Reliability	Circuit breakers, retry policies, health checks, graceful degradation
Performance	Caching strategies, optimized queries, CDN usage, async operations
Security	OAuth 2.0/OIDC, HTTPS everywhere, input validation, audit logging
Maintainability	Clean architecture, automated testing, comprehensive documentation
Observability	Distributed tracing, structured logging, metrics collection, health monitoring

4.4 Deployment Strategy

Container-First Approach

All services are containerized using Docker with multi-stage builds for optimized image sizes and security.

Infrastructure as Code

• Azure Bicep templates for infrastructure provisioning
• GitHub Actions for CI/CD pipeline automation

Environment Strategy

Environment	Purpose	Deployment Method
Development	Local development	Docker Compose + .NET Aspire
Staging	Integration testing	Azure Container Apps (staging)
Production	Live system	Azure Container Apps (production)

4.5 Security Strategy

Authentication and Authorization

Security Measures

Security Layer	Implementation
API Gateway	Rate limiting, request validation, token verification
Service Level	Authorization policies, input validation, output encoding
Data Layer	Encryption at rest, secure connection strings, backup encryption
Network	HTTPS/TLS, network segmentation, WAF protection
Monitoring	Security event logging, anomaly detection, audit trails

4.6 AI Integration Strategy

AI Services Architecture

• Text Embedding: Nomic Embed Text for semantic search capabilities
• Conversational AI: Gemma 3 for intelligent chatbot interactions
• Search Enhancement: AI-powered search with natural language understanding

AI Service Integration

4.6 Related Architecture Decisions

The solution strategy is supported by detailed Architecture Decision Records (ADRs):

Infrastructure & Platform

• ADR-001: Microservices Architecture - Domain-driven service boundaries
• ADR-003: .NET Aspire for Cloud-Native Development - Cloud-native framework choice
• ADR-007: Container-First Deployment Strategy - Containerization approach
• ADR-008: API Gateway Pattern Implementation - Unified API access strategy

Data & Events

• ADR-004: PostgreSQL as Primary Database - Database technology selection
• ADR-002: Event-Driven Architecture with CQRS - Event-driven communication strategy

Security & Communication

• ADR-005: Keycloak for Identity Management - Identity and access management
• ADR-006: SignalR for Real-time Communication - Real-time communication approach

AI & Intelligence

• ADR-009: AI Integration Strategy - AI services integration approach

For a comprehensive overview of all architectural decisions, see the Architecture Decisions section.