Architecture

This document provides a detailed introduction to the overall architecture design, core component relationships, and processing flows of the Wow framework.

Overall Architecture

Core Components

Component Relationship Diagram

Component Description

Component	Responsibility	Interface
CommandGateway	Command entry point, supports wait strategies	CommandGateway
CommandBus	Command transport channel	CommandBus
CommandProcessor	Command processing, loads aggregate root and executes	CommandProcessor
EventStore	Event persistent storage	EventStore
SnapshotRepository	Snapshot storage, optimizes aggregate loading	SnapshotRepository
EventBus	Domain event transport channel	EventBus
StateEventBus	State event transport channel	StateEventBus
EventProcessor	Event processor base class	EventProcessor
ProjectionProcessor	Projection processing, updates read model	ProjectionProcessor
SagaProcessor	Saga orchestration, handles distributed transactions	SagaProcessor
QueryService	Query service, reads from read model	QueryService

Command Processing Flow

Flow Description

1. Command Sending: Client sends command through CommandGateway
2. Command Routing: CommandBus routes to corresponding processor based on aggregate type
3. Aggregate Loading: Rebuild aggregate state from snapshot and event store
4. Command Execution: Aggregate root processes command, produces domain events
5. Event Persistence: Events appended to EventStore
6. Snapshot Saving: Save snapshot based on strategy
7. Event Publishing: Domain events published to EventBus

Event Processing Flow

CQRS Architecture Implementation

The Wow framework implements a complete CQRS (Command Query Responsibility Segregation) architecture:

Write Model Responsibilities

• Process business commands
• Execute business rule validation
• Produce domain events
• Maintain transactional consistency

Read Model Responsibilities

• Respond to query requests
• Provide optimized data views
• Support complex query conditions
• Eventual consistency

Event Sourcing Implementation

Event Storage Structure

State Rebuild Flow

Extension Points

The Wow framework provides rich extension points:

Extension Point	Description	Use Case
CommandBus	Command bus implementation	Custom message transport
EventBus	Event bus implementation	Custom event distribution
EventStore	Event store implementation	Custom storage backend
SnapshotRepository	Snapshot storage implementation	Custom snapshot strategy
IdGenerator	ID generator	Custom ID format
WaitStrategy	Wait strategy	Custom synchronization mechanism

Design Principles

Single Responsibility

Each component is responsible for only one concern, complex functionality is achieved through composition.

Dependency Inversion

Core modules depend on abstract interfaces, concrete implementations are provided through extension modules.

Open-Closed Principle

Through extension point mechanism, extend functionality without modifying core code.

Event-Driven

System is decoupled through events, supporting asynchronous processing and eventual consistency.