RESTful Interview Questions and Answers for 5 years experience

1. What is REST?

   • Answer: REST, or Representational State Transfer, is an architectural style for designing networked applications. It uses a stateless, client-server, cacheable communication protocol, and a uniform interface to transfer representations of resources in a hypermedia-driven manner.

2. Explain the constraints of RESTful architecture.

   • Answer: The key constraints are: Client-Server, Stateless, Cacheable, Uniform Interface (using standard methods like GET, POST, PUT, DELETE), Layered System, Code on Demand (optional).

3. What are the HTTP methods used in REST? Explain each.

   • Answer: GET (retrieves a resource), POST (creates a new resource), PUT (updates an existing resource), DELETE (deletes a resource), PATCH (partially modifies a resource), HEAD (retrieves metadata), OPTIONS (describes communication options).

4. What is a RESTful API?

   • Answer: A RESTful API is an application programming interface that conforms to the constraints of RESTful architecture. It uses HTTP requests to interact with resources.

5. Explain the concept of resources in REST.

   • Answer: Resources represent the data or functionality accessed through the API. They are identified by URIs (Uniform Resource Identifiers).

6. What is HATEOAS?

   • Answer: HATEOAS (Hypermedia as the Engine of Application State) is a constraint of REST where the API responses include links to related resources, allowing clients to discover available actions without prior knowledge of the API's structure.

7. What is the difference between PUT and PATCH?

   • Answer: PUT replaces the entire resource with the provided data, while PATCH updates only specific parts of the resource.

8. Explain RESTful API design best practices.

   • Answer: Use meaningful URIs, consistent naming conventions, proper HTTP methods, appropriate status codes, versioning, good documentation, security considerations (authentication and authorization), error handling, and rate limiting.

9. What are HTTP status codes and their importance in REST?

   • Answer: HTTP status codes (e.g., 200 OK, 404 Not Found, 500 Internal Server Error) communicate the outcome of a request. They are crucial for error handling and client-side logic.

10. How do you handle errors in a RESTful API?

    • Answer: Use appropriate HTTP status codes, provide informative error messages in the response body (JSON or XML), and consider using standard error formats.

11. How do you implement authentication and authorization in a RESTful API?

    • Answer: Common methods include API keys, OAuth 2.0, JWT (JSON Web Tokens), Basic Authentication. The choice depends on security requirements and the application context.

12. What is API versioning and why is it important?

    • Answer: API versioning allows for backward compatibility when making changes to the API. It prevents breaking existing clients when updating the API.

13. Explain different API versioning strategies.

    • Answer: URI versioning (e.g., /v1/users), Header versioning (e.g., Accept: application/vnd.api+json;version=1), Content negotiation (using Accept header to specify format and version), Query parameter versioning (e.g., ?version=1).

14. What is rate limiting in a RESTful API?

    • Answer: Rate limiting controls the number of requests a client can make within a given time frame. This prevents abuse and protects the API from overload.

15. How do you handle caching in a RESTful API?

    • Answer: Use HTTP caching headers (e.g., Cache-Control, ETag) to instruct clients and intermediaries (like CDNs) on how to cache responses. This improves performance and reduces server load.

16. What are some common tools and technologies used for developing RESTful APIs?

    • Answer: Frameworks like Spring Boot (Java), Node.js with Express.js, Django REST framework (Python), Ruby on Rails, etc. Databases like PostgreSQL, MySQL, MongoDB. API gateways like Kong, Apigee.

17. Describe your experience with API testing and documentation.

    • Answer: (This requires a personalized answer based on your experience. Mention tools like Postman, Swagger, OpenAPI, and your testing methodologies.)

18. Explain your experience with different data formats used in REST APIs (JSON, XML).

    • Answer: (This requires a personalized answer. Explain your familiarity with JSON and XML, including parsing and serialization.)

19. How do you ensure the scalability and performance of a RESTful API?

    • Answer: Techniques include database optimization, caching, load balancing, using message queues, and choosing appropriate hardware and infrastructure.

20. What is the difference between REST and GraphQL?

    • Answer: REST uses multiple endpoints to fetch data, whereas GraphQL allows fetching multiple resources with a single request, offering more flexibility and efficiency.

21. What is an API gateway and its benefits?

    • Answer: An API gateway acts as a reverse proxy, providing security, authentication, and management capabilities for multiple backend APIs.

22. Explain your experience with designing and implementing microservices using RESTful APIs.

    • Answer: (This requires a personalized answer, detailing your experience with microservice architecture and communication patterns between services using REST.)

23. Describe your experience with different API security measures.

    • Answer: (This requires a personalized answer. Discuss your experience with authentication, authorization, input validation, output encoding, rate limiting, and other security best practices.)

24. What is CORS (Cross-Origin Resource Sharing) and how does it work?

    • Answer: CORS is a mechanism that allows web pages from one origin to access resources from a different origin. It uses HTTP headers to control access.

25. How do you handle large datasets in a RESTful API?

    • Answer: Techniques include pagination, filtering, sorting, and using cursor-based pagination to improve performance and reduce bandwidth usage.

26. What are some common challenges you have faced while working with RESTful APIs?

    • Answer: (This requires a personalized answer. Be honest and mention challenges like versioning, scalability, security, error handling, and debugging.)

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