1. What does REST stand for?

• REST stands for Representational State Transfer. It’s an architectural style for designing networked applications.

2. What is a REST API?

• A REST API is an Application Programming Interface that allows different software systems to communicate over a network. It enables these systems to interact and exchange data using standard HTTP methods like GET, POST, PUT, DELETE.

3. What are RESTful web services?

• RESTful web services adhere to the principles of REST architecture. They use standard protocols, such as HTTP, and follow specific design principles like statelessness, uniform interfaces, and resource-based URLs.

4. Explain cache-control headers.

• Cache-control headers are part of HTTP responses and instruct caching mechanisms on how to handle and store responses. They dictate whether a response can be cached, and if so, for how long and by whom (public, private, No-Store).

5. What are the features of RESTful web services?

• RESTful services exhibit several key features:

• Client-server decoupling: Separation of concerns between client and server.
• Stateless: Each request from a client to the server contains all necessary information.
• Uniform interface: Resources are uniquely identified and manipulated using standard methods.
• Layered system: Organized in layers for scalability and flexibility.
• Cacheable: Responses from the server can be cached to improve performance.
• Code on demand: Servers can provide executable code to clients on request.

6. What defines messaging in RESTful web services?

• Messaging in REST refers to the exchange of information between the client and server through HTTP requests and responses. It encompasses sending requests for resources and receiving corresponding responses.

7. Define ‘Addressing’ in RESTful web services.

• ‘Addressing’ in REST refers to the process of locating and accessing resources on the server using Uniform Resource Identifiers (URIs). It involves mapping resources to unique URIs for identification and retrieval.

8. Why are REST services easily scalable?

• REST services are stateless, meaning they don’t store client session information on the server. This characteristic allows easy horizontal scaling by distributing the load across multiple servers, as each request contains all necessary information.

9. What are Idempotent methods?

• Idempotent methods in REST are operations that produce the same result regardless of the number of times they are executed. These methods are designed to prevent unintended side effects caused by multiple requests.

10. How can RESTful web services be tested?

• RESTful services can be tested using tools like Swagger, Postman, and REST Assured. These tools allow developers to simulate API requests, inspect responses, test various parameters, headers, and document API endpoints.

11. What are payloads in RESTful web services?

• Payloads refer to the data transmitted in the body of HTTP requests, specifically through methods like POST or GET. This data contains the information or content sent to or received from the server.

12. Is there a maximum payload size for POST methods?

• In theory, there’s no strict maximum limit for payload size in POST methods. However, larger payloads can impact server response time and consume more bandwidth.

13. Which protocol do REST APIs use?

• REST APIs primarily utilize the HTTP protocol for communication between clients and servers. It leverages standard HTTP methods like GET, POST, PUT, DELETE, etc.

14. What markup languages represent resources in REST APIs?

• Resources in REST APIs are commonly represented using XML (extensible markup language) and JSON (JavaScript Object Notation) formats. These formats offer structured ways to represent data.

15. How do POST and PUT methods differ?

• POST is used to create new resources on the server, whereas PUT is utilized to replace or update existing resources at specific URIs. POST is not idempotent, while PUT is.

16. Which HTTP request methods does REST support?

• REST supports various HTTP methods such as GET, POST, PUT, DELETE, HEAD, OPTIONS, etc., each serving different purposes for resource manipulation.

17. What does CRUD stand for?

• CRUD stands for Create, Read, Update, Delete. It represents the basic operations that can be performed on database entities or resources in RESTful services.

18. What are the main components of an HTTP response?

• The primary components of an HTTP response include the HTTP version, status line (status code and reason phrase), response header, and response body containing the requested data.

19. What are common HTTP response status codes in REST API?

• Common status codes include 200 OK (successful request), 201 Created (resource created), 400 Bad Request (invalid request), 404 Not Found (resource not found), 500 Internal Server Error (server error), etc.

20. Define a resource in REST.

• In REST, a resource is an object or entity that can be accessed and manipulated. It’s identified by a unique URI and typically includes data and relationships with other resources.

Conclusion

In conclusion, mastering the essential concepts and principles of REST APIs is crucial for success in interviews. Understanding HTTP methods, resource identification, statelessness, idempotent operations, testing methodologies, response handling, caching, CRUD operations, security measures, content negotiation, and error handling are fundamental. Moreover, being familiar with differences between REST and SOAP, hypermedia, documentation practices, performance optimization, real-world applications, and staying updated with advanced trends are key for excelling in REST API interviews. Continuous learning and practical application of these concepts will not only help ace interviews but also pave the way for success in building robust and efficient RESTful APIs in the professional landscape.