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intermediate Phase · API Design Interview

Request / Response Design

Design request payloads and response structures.

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Request/Response

Request Format

POST /products
{
  "name": "Laptop",
  "price": 999.99,
  "categoryId": 1
}

Response Format

{
  "id": 123,
  "name": "Laptop",
  "price": 999.99,
  "category": {
    "id": 1,
    "name": "Electronics"
  },
  "createdAt": "2025-01-15T10:30:00Z"
}

Key Points

  • Understanding API Design: Request/Response is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

API Best Practices

Design Principles

  • Use nouns, not verbs
  • Plural resource names
  • Consistent naming conventions
  • Proper HTTP status codes

Versioning

  • URI versioning (/v1/resource)
  • Header versioning
  • Deprecation policy

Documentation

  • OpenAPI/Swagger specs
  • Request/Response examples
  • Error code documentation
  • Rate limit documentation

Key Points

  • Understanding API Design: Request/Response is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0 / 3 solved
Implement API Design: Request/Response

Design and implement a solution for API Design: Request/Response in a backend system. Consider scalability, error handling, and production readiness.

Solution 
// API Design: Request/Response implementation
// Key aspects: validation, error handling, logging, testing

public class APIDesignRequestResponse {
    // Production-ready implementation
}
API Design: Request/Response Edge Cases

Identify and handle edge cases for API Design: Request/Response. What happens under high load, with invalid input, or during failures?

Solution 
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
API Design: Request/Response Testing Strategy

Write a testing strategy for API Design: Request/Response. Include unit tests, integration tests, and performance tests.

Solution 
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. Response should include?

Question 1 options

2. DTOs are used for?

Question 2 options

3. What is a common mistake when implementing API Design: Request/Response?

Question 3 options

Flashcards

Question

Response includes?

Click to reveal answer

Answer

Data with nested resources

Question

DTOs purpose?

Click to reveal answer

Answer

Separate API contracts from entities

Question

API Design: Request/Response best practices

Click to reveal answer

Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1. Design clean request/response formats
  • 2. Include nested resources in response
  • 3. Use DTOs for API contract separation
  • 4. Timestamps in ISO format

Interview Tips

  • • Design request/response formats
  • • Handle nested data

Cheat Sheet

Request/Response

  • Clean JSON format
  • Nested: include related resources
  • DTOs: separate API from entities
  • Timestamps: ISO format