Bff Service

{{SERVICE_NAME_PASCAL}} BFF Skill

Service Type: Backend for Frontend

Aggregates data from multiple services for specific frontend needs.

Characteristics

• Aggregation: Combines data from multiple services
• Caching: Caffeine cache for frequently accessed data
• Parallel calls: Uses CompletableFuture for concurrent requests
• Graceful degradation: Fallbacks when services are down
• No database: Stateless aggregator

Package Structure

com.company.{{SERVICE_NAME}}/
├── config/         # Cache, Feign configuration
├── aggregator/     # Business logic for combining data
├── client/         # Feign clients to backend services
└── dto/            # Response DTOs for frontend

Aggregation Pattern

@Cacheable(value = "dashboard", key = "#userId")
@CircuitBreaker(name = "dashboard", fallbackMethod = "fallback")
public DashboardResponse getDashboard(Long userId) {
    // Parallel calls
    var userFuture = CompletableFuture.supplyAsync(() -> userClient.get(userId));
    var ordersFuture = CompletableFuture.supplyAsync(() -> orderClient.get(userId));

    // Wait and combine
    CompletableFuture.allOf(userFuture, ordersFuture).join();

    return DashboardResponse.builder()
        .user(userFuture.join())
        .orders(ordersFuture.join())
        .build();
}

Commands

mvn spring-boot:run
curl http://localhost:808X/api/dashboard/1