2nd/10_Wiki/Topics/Architecture/복잡한 비즈니스 도메인 (금융 헬스케어 이커머스 등).md

---
id: wiki-2026-0508-복잡한-비즈니스-도메인-금융-헬스케어-이커머스-등
title: 복잡한 비즈니스 도메인 (금융, 헬스케어, 이커머스 등)
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Complex Business Domains, Domain-Heavy Systems]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [domain-driven-design, business-domain, architecture, ddd]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: TypeScript
  framework: NestJS / Spring Boot
---

# 복잡한 비즈니스 도메인 (금융, 헬스케어, 이커머스)

## 매 한 줄
> **"매 복잡한 도메인은 코드의 형태가 아니라 도메인 모델의 형태로 정복된다"**. 매 금융, 헬스케어, 이커머스는 각각 규제, 정확성, 동시성 압력이 다르며 매 DDD bounded context + invariant enforcement + event sourcing 이 2026 의 default approach.

## 매 핵심

### 매 도메인별 압력
- **금융**: 매 정확성 (decimal arithmetic, no float), audit trail, regulatory (SOX, MiFID II, Basel III, K-AML), idempotency.
- **헬스케어**: 매 PHI privacy (HIPAA, GDPR Art.9, K-MyData), HL7/FHIR interoperability, clinical decision support, audit immutability.
- **이커머스**: 매 inventory consistency, payment idempotency, fraud detection, peak-load (Black Friday) elasticity, multi-currency/tax.

### 매 공통 architectural pillars
- **Bounded Context**: 매 Order, Payment, Inventory, Patient, Claim 의 명확한 ownership boundaries.
- **Aggregate root + invariants**: 매 transactional consistency unit, business rule enforcement.
- **Event Sourcing + CQRS**: 매 audit trail + read/write workload split.
- **Sagas / Process Managers**: 매 distributed transaction 대신 compensating actions.
- **Anti-corruption layer**: 매 legacy 시스템 (COBOL, HL7v2, EDI) 과의 격리.

### 매 응용
1. 매 금융: 매 ledger as append-only event log, double-entry bookkeeping, eventual consistency 위 strong invariants.
2. 매 헬스케어: 매 FHIR resource model + consent management + audit per-field-access.
3. 매 이커머스: 매 inventory reservation saga + payment authorization/capture + outbox pattern.

## 💻 패턴

### Decimal money (금융)
```typescript
import Decimal from 'decimal.js';

class Money {
  constructor(readonly amount: Decimal, readonly currency: string) {}
  static of(amount: string, currency: string) {
    return new Money(new Decimal(amount), currency);
  }
  add(other: Money): Money {
    if (other.currency !== this.currency) throw new Error('currency mismatch');
    return new Money(this.amount.plus(other.amount), this.currency);
  }
  // never use number — IEEE-754 binary float ruins cents
}
```

### Aggregate with invariants (이커머스)
```typescript
class Order {
  private items: OrderItem[] = [];
  private status: 'draft'|'placed'|'paid'|'fulfilled'|'cancelled' = 'draft';

  addItem(productId: string, qty: number, unitPrice: Money) {
    if (this.status !== 'draft') throw new Error('cannot modify placed order');
    if (qty <= 0) throw new Error('qty>0');
    this.items.push(new OrderItem(productId, qty, unitPrice));
  }

  place(): OrderPlaced {
    if (this.items.length === 0) throw new Error('empty order');
    this.status = 'placed';
    return { type: 'OrderPlaced', orderId: this.id, total: this.total() };
  }
}
```

### Saga: payment + inventory (이커머스)
```typescript
async function placeOrderSaga(orderId: string) {
  const reservation = await inventory.reserve(orderId);
  try {
    const payment = await payments.authorize(orderId);
    try {
      await inventory.commit(reservation.id);
      await payments.capture(payment.id);
    } catch (e) {
      await payments.void(payment.id);
      await inventory.release(reservation.id);
      throw e;
    }
  } catch (e) {
    await inventory.release(reservation.id);
    throw e;
  }
}
```

### Event sourcing (금융 ledger)
```typescript
type LedgerEvent =
  | { type: 'AccountOpened', accountId: string, currency: string }
  | { type: 'Debited', accountId: string, amount: string, txId: string }
  | { type: 'Credited', accountId: string, amount: string, txId: string };

function reduce(events: LedgerEvent[]): Account {
  return events.reduce((acc, e) => {
    if (e.type === 'AccountOpened') return { ...acc, currency: e.currency, balance: new Decimal(0) };
    if (e.type === 'Debited') return { ...acc, balance: acc.balance.minus(e.amount) };
    if (e.type === 'Credited') return { ...acc, balance: acc.balance.plus(e.amount) };
    return acc;
  }, {} as Account);
}
```

### FHIR resource (헬스케어)
```typescript
interface Patient {
  resourceType: 'Patient';
  id: string;
  identifier: Array<{ system: string; value: string }>;
  name: HumanName[];
  birthDate: string;            // ISO8601
  consent?: Reference<Consent>; // K-MyData / HIPAA consent linkage
}
```

### Outbox pattern (이커머스 reliability)
```typescript
await db.transaction(async tx => {
  await tx.insert('orders', order);
  await tx.insert('outbox', {
    id: ulid(),
    aggregateId: order.id,
    type: 'OrderPlaced',
    payload: JSON.stringify(event),
    createdAt: new Date(),
  });
});
// async outbox poller publishes to Kafka — at-least-once delivery
```

### Anti-corruption layer (legacy HL7v2 → FHIR)
```typescript
class HL7v2ToFhirAdapter {
  translate(adt: Hl7v2Message): Patient {
    const pid = adt.segment('PID');
    return {
      resourceType: 'Patient',
      id: pid.field(3).value(),
      name: [{ family: pid.field(5).component(1), given: [pid.field(5).component(2)] }],
      birthDate: this.parseHl7Date(pid.field(7).value()),
      identifier: [{ system: 'urn:hospital:mrn', value: pid.field(3).value() }],
    };
  }
}
```

### Idempotency key (payments)
```typescript
async function charge(req: ChargeRequest, idempotencyKey: string) {
  const existing = await db.idempotency.findOne({ key: idempotencyKey });
  if (existing) return existing.response;
  const result = await processor.charge(req);
  await db.idempotency.insert({ key: idempotencyKey, response: result, ttl: '24h' });
  return result;
}
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| 금융 ledger | Event sourcing + double-entry |
| 헬스케어 record | FHIR + consent + audit log |
| 이커머스 order flow | Saga + outbox + idempotency |
| Cross-domain integration | Anti-corruption layer |
| Strong invariant | Aggregate boundary, single-writer |
| High read throughput | CQRS read model |

**기본값**: 매 Bounded Context first, Aggregate + invariants second, Events as integration third.

## 🔗 Graph
- 부모: [[Domain-Driven Design]] · [[Bounded_Context]]
- 변형: [[Event Sourcing]] · [[CQRS]]
- 응용: [[이커머스의 실시간 재고 관리]] · [[엔터프라이즈 소프트웨어 개발]]
- Adjacent: [[ACID Transactions]] · [[비기능 요구사항 (Non-functional Requirements)]]

## 🤖 LLM 활용
**언제**: 매 도메인 모델링, invariant 추출, ubiquitous language 정리, regulatory mapping (HIPAA → field-level access policy).
**언제 X**: 매 specific compliance interpretation (변호사·CISO 검토 필수), 매 production money handling (independent audit 필요).

## ❌ 안티패턴
- **Anonymic domain model**: 매 getter/setter 만 있는 비즈니스 로직 없는 entity → service 비대화.
- **Float for money**: 매 0.1 + 0.2 ≠ 0.3 의 IEEE-754 catastrophe.
- **Distributed transaction (2PC)**: 매 micro-services 간 2PC → coordinator deadlock + low availability.
- **One DB for all bounded contexts**: 매 schema coupling 으로 deploy lock-step.
- **PHI in logs**: 매 healthcare/finance 의 unmasked PII/PHI 가 log 에 → instant compliance breach.

## 🧪 검증 / 중복
- Verified (Evans "Domain-Driven Design", Vernon "Implementing DDD", FHIR R5 spec, ISO 20022).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — finance/healthcare/ecommerce DDD patterns 정리 |