백엔드 개발 패턴

확장 가능한 서버 사이드 애플리케이션을 위한 백엔드 아키텍처 패턴과 모범 사례.

활성화 시점

• REST 또는 GraphQL API 엔드포인트를 설계할 때
• Repository, Service 또는 Controller 레이어를 구현할 때
• 데이터베이스 쿼리를 최적화할 때 (N+1, 인덱싱, 커넥션 풀링)
• 캐싱을 추가할 때 (Redis, 인메모리, HTTP 캐시 헤더)
• 백그라운드 작업이나 비동기 처리를 설정할 때
• API를 위한 에러 처리 및 유효성 검사를 구조화할 때
• 미들웨어를 구축할 때 (인증, 로깅, 요청 제한)

API 설계 패턴

RESTful API 구조

// PASS: Resource-based URLs
GET    /api/markets                 # List resources
GET    /api/markets/:id             # Get single resource
POST   /api/markets                 # Create resource
PUT    /api/markets/:id             # Replace resource
PATCH  /api/markets/:id             # Update resource
DELETE /api/markets/:id             # Delete resource

// PASS: Query parameters for filtering, sorting, pagination
GET /api/markets?status=active&sort=volume&limit=20&offset=0

Repository 패턴

// Abstract data access logic
interface MarketRepository {
  findAll(filters?: MarketFilters): Promise<Market[]>
  findById(id: string): Promise<Market | null>
  findByIds(ids: string[]): Promise<Market[]>
  create(data: CreateMarketDto): Promise<Market>
  update(id: string, data: UpdateMarketDto): Promise<Market>
  delete(id: string): Promise<void>
}

class SupabaseMarketRepository implements MarketRepository {
  async findAll(filters?: MarketFilters): Promise<Market[]> {
    let query = supabase.from('markets').select('*')

    if (filters?.status) {
      query = query.eq('status', filters.status)
    }

    if (filters?.limit) {
      query = query.limit(filters.limit)
    }

    const { data, error } = await query

    if (error) throw new Error(error.message)
    return data
  }

  // Other methods...
}

Service 레이어 패턴

// Business logic separated from data access
class MarketService {
  constructor(private marketRepo: MarketRepository) {}

  async searchMarkets(query: string, limit: number = 10): Promise<Market[]> {
    // Business logic
    const embedding = await generateEmbedding(query)
    const results = await this.vectorSearch(embedding, limit)

    // Fetch full data
    const markets = await this.marketRepo.findByIds(results.map(r => r.id))

    // Sort by similarity
    return [...markets].sort((a, b) => {
      const scoreA = results.find(r => r.id === a.id)?.score || 0
      const scoreB = results.find(r => r.id === b.id)?.score || 0
      return scoreA - scoreB
    })
  }

  private async vectorSearch(embedding: number[], limit: number) {
    // Vector search implementation
  }
}

미들웨어 패턴

// Request/response processing pipeline
export function withAuth(handler: NextApiHandler): NextApiHandler {
  return async (req, res) => {
    const token = req.headers.authorization?.replace('Bearer ', '')

    if (!token) {
      return res.status(401).json({ error: 'Unauthorized' })
    }

    try {
      const user = await verifyToken(token)
      req.user = user
      return handler(req, res)
    } catch (error) {
      return res.status(401).json({ error: 'Invalid token' })
    }
  }
}

// Usage
export default withAuth(async (req, res) => {
  // Handler has access to req.user
})

데이터베이스 패턴

쿼리 최적화

// PASS: GOOD: Select only needed columns
const { data } = await supabase
  .from('markets')
  .select('id, name, status, volume')
  .eq('status', 'active')
  .order('volume', { ascending: false })
  .limit(10)

// FAIL: BAD: Select everything
const { data } = await supabase
  .from('markets')
  .select('*')

N+1 쿼리 방지

// FAIL: BAD: N+1 query problem
const markets = await getMarkets()
for (const market of markets) {
  market.creator = await getUser(market.creator_id)  // N queries
}

// PASS: GOOD: Batch fetch
const markets = await getMarkets()
const creatorIds = markets.map(m => m.creator_id)
const creators = await getUsers(creatorIds)  // 1 query
const creatorMap = new Map(creators.map(c => [c.id, c]))

markets.forEach(market => {

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