Architecture
System Design
Architecture principles for Business-as-Code applications
Architectural principles and patterns for Business-as-Code systems.
Core Architecture
Business-as-Code applications follow a layered, event-driven architecture:
graph TB
subgraph Presentation["Presentation Layer"]
UI[Web/Mobile UI]
API[API Gateway]
end
subgraph Application["Application Layer"]
BL[Business Logic<br/>Event Handlers]
WF[Workflows]
AI[AI Engine]
end
subgraph Domain["Domain Layer"]
Entities[Semantic Entities]
Relations[Relationships]
Events[Domain Events]
end
subgraph Infrastructure["Infrastructure Layer"]
DB[(Graph Database)]
Queue[Event Queue]
Storage[Object Storage]
Cache[Cache Layer]
end
UI --> API
API --> BL
BL --> WF
BL --> AI
WF --> Events
Events --> Queue
Queue --> BL
BL --> Entities
Entities --> Relations
Relations --> DB
Events --> DB
Key Principles
1. Semantic-First
Everything is modeled using semantic types:
// Good: Semantic types
const customer = await $.Person.create({
$type: 'Person',
givenName: 'Alice',
email: '[email protected]',
})
// Avoid: Custom types
const user = { name: 'Alice', email: '[email protected]' }2. Event-Driven
State changes trigger events, events trigger workflows:
// Events coordinate system behavior
on($.Order.created, handleOrderCreated)
on($.Payment.processed, handlePaymentProcessed)
on($.Shipment.created, handleShipmentCreated)3. AI-Native
AI is embedded throughout, not bolted on:
// AI makes business decisions
const decision = await ai.decide('pricing', context)
const recommendations = await ai.recommend({ type, for, context })4. Distributed by Default
Components are loosely coupled and independently deployable:
- Event-driven communication
- Async-first operations
- Service independence
- Horizontal scalability
Component Architecture
Entities & Relationships
// Entity storage
interface EntityStore {
create(type: string, data: any): Promise<Entity>
get(type: string, id: string): Promise<Entity>
update(type: string, id: string, data: any): Promise<Entity>
delete(type: string, id: string): Promise<void>
list(type: string, query: Query): Promise<Entity[]>
}
// Relationship storage
interface RelationStore {
relate(subject: Entity, predicate: string, object: Entity): Promise<void>
unrelate(subject: Entity, predicate: string, object: Entity): Promise<void>
related(subject: Entity, predicate: string, type: string): Promise<Entity[]>
query(pattern: GraphPattern): Promise<Entity[]>
}Event System
// Event bus
interface EventBus {
on(eventType: string, handler: EventHandler): void
off(eventType: string, handler: EventHandler): void
emit(eventType: string, data: any): Promise<void>
}
// Event store (for event sourcing)
interface EventStore {
append(aggregateId: string, event: Event): Promise<void>
getEvents(aggregateId: string): Promise<Event[]>
subscribe(eventType: string, handler: EventHandler): void
}AI Integration
// AI service interface
interface AIService {
generate(type: string, context: any): Promise<any>
decide(strategy: string, context: any): Promise<Decision>
recommend(params: RecommendParams): Promise<any[]>
analyze(metric: string, data: any): Promise<Analysis>
}Data Flow
Typical request flow through the system:
sequenceDiagram
participant C as Client
participant A as API Gateway
participant B as Business Logic
participant AI as AI Engine
participant E as Event Bus
participant D as Database
C->>A: HTTP Request
A->>B: Route to Handler
B->>D: Query Data
D-->>B: Return Data
B->>AI: Request Decision
AI-->>B: Return Decision
B->>D: Update State
B->>E: Emit Event
E-->>B: Trigger Handlers
B-->>A: Response
A-->>C: HTTP Response
Scalability Patterns
Horizontal Scaling
- Stateless application servers
- Distributed event processing
- Sharded databases
- CDN for static assets
Caching Strategy
// Multi-layer caching
interface CacheStrategy {
// L1: In-memory (milliseconds)
memory: MemoryCache
// L2: Redis (sub-millisecond)
distributed: RedisCache
// L3: CDN (edge caching)
cdn: CDNCache
}Async Processing
// Long-running operations
on($.Order.created, async (order) => {
// Quick acknowledgment
await db.update($.Order, order.$id, { status: 'processing' })
// Async processing
await queue.enqueue('order-fulfillment', order)
return { status: 'accepted' }
})Security Architecture
Authentication & Authorization
// JWT-based auth
interface AuthService {
authenticate(credentials: Credentials): Promise<Token>
authorize(token: Token, resource: string, action: string): Promise<boolean>
refresh(token: Token): Promise<Token>
}
// Role-based access control
const permissions = {
admin: ['*'],
seller: ['order:read', 'order:update', 'product:*'],
customer: ['order:read', 'profile:*'],
}Data Protection
- Encryption at rest (AES-256)
- Encryption in transit (TLS 1.3)
- PII tokenization
- Audit logging
Monitoring & Observability
Metrics
// Track key metrics
interface Metrics {
// Application metrics
requestRate: number
errorRate: number
p95Latency: number
// Business metrics
ordersPerSecond: number
revenue: number
activeUsers: number
// AI metrics
aiDecisionAccuracy: number
aiLatency: number
}Logging
// Structured logging
log.info('Order processed', {
orderId: order.$id,
customer: order.customer.$id,
amount: order.totalPrice,
duration: processingTime,
})Tracing
// Distributed tracing
const span = tracer.startSpan('process-order')
span.setTag('order.id', order.$id)
try {
await processOrder(order)
span.setTag('success', true)
} catch (error) {
span.setTag('error', true)
span.log({ error: error.message })
} finally {
span.finish()
}Best Practices
1. Design for Failure
- Circuit breakers
- Retry with backoff
- Graceful degradation
- Fallback strategies
2. Keep State Minimal
- Event sourcing
- CQRS for reads
- Cache invalidation
3. Optimize for Change
- Feature flags
- Canary deployments
- A/B testing infrastructure
4. Monitor Everything
- Application metrics
- Business metrics
- AI performance
- User experience
Summary
Business-as-Code architecture is:
- Semantic - Everything has meaning
- Event-Driven - Async by default
- AI-Native - Intelligence embedded
- Distributed - Scale horizontally
- Observable - Monitor and learn
Next: Deployment →