What is Rest API? How is it different from HTTP?

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A REST API (Representational State Transfer Application Programming Interface) is a set of rules and conventions for building and interacting with web services. It allows different software systems to communicate over the internet using standard HTTP methods.

Key Concepts

  1. REST (Representational State Transfer):
  2. Explanation: REST is an architectural style for designing networked applications. It relies on stateless communication and uses standard HTTP methods to perform operations on resources. Resources are identified by URLs, and the state of the resource can be represented in various formats, typically JSON or XML.
  3. Usage: REST APIs are widely used in web services, enabling communication between a client (e.g., web browser, mobile app) and a server.
  4. API (Application Programming Interface):
  5. Explanation: An API is a set of definitions and protocols that allow one software application to interact with another. In the context of REST, an API defines how resources are accessed and manipulated using HTTP methods.
  6. Usage: REST APIs expose endpoints that allow clients to perform CRUD (Create, Read, Update, Delete) operations on resources.
  7. Key Features of REST API:
  8. Statelessness: Each request from a client to a server must contain all the information the server needs to fulfill the request. The server does not store any state between requests.
  9. Client-Server Architecture: The client and server are separate entities, allowing them to evolve independently.
  10. Cacheability: Responses from the server can be cached by the client to improve performance.
  11. Layered System: The architecture allows for a layered approach, where different layers (e.g., security, load balancing) can be added without affecting the client-server interaction.
  12. Uniform Interface: REST APIs follow a uniform interface, which simplifies and decouples the architecture. It includes principles like using standard HTTP methods, resource identification through URLs, and stateless communication.
  13. HTTP Methods in REST:
  14. GET: Retrieve information about a resource.
  15. POST: Create a new resource.
  16. PUT: Update an existing resource or create one if it doesn't exist.
  17. DELETE: Remove a resource.
  18. PATCH: Partially update an existing resource.

❓ How is REST API Different from HTTP?

  1. HTTP as a Protocol:
  2. Explanation: HTTP (Hypertext Transfer Protocol) is a protocol used for transmitting data over the internet. It defines how messages are formatted and transmitted, and what actions web servers and browsers should take in response to various commands.
  3. Usage: HTTP is the underlying protocol that REST APIs use to communicate between clients and servers. It provides the methods (GET, POST, PUT, DELETE, etc.) that REST APIs utilize to perform operations on resources.
  4. REST as an Architectural Style:
  5. Explanation: REST is not a protocol but an architectural style that defines how to structure APIs using HTTP. It uses HTTP methods in a stateless, resource-oriented manner to perform CRUD operations on resources.
  6. Usage: REST defines conventions and constraints on how HTTP should be used to create web services. For example, using GET to retrieve data, POST to create new data, and so on.
  7. REST API vs. HTTP:
  8. Level of Abstraction:
    • REST API: A higher-level abstraction that builds on top of HTTP. It focuses on how resources are represented, accessed, and manipulated using HTTP.
    • HTTP: A lower-level protocol that specifies how data is exchanged over the web, without imposing any constraints on how it should be used.
  9. Flexibility:
    • REST API: Enforces a set of principles that lead to predictable, scalable, and maintainable web services.
    • HTTP: More general-purpose, allowing for various types of communication that are not necessarily resource-oriented (e.g., sending raw data, streaming media).
  10. Usage:
    • REST API: Used specifically for designing web services that adhere to REST principles.
    • HTTP: Used for a wide range of communication tasks on the web, including serving web pages, downloading files, and interacting with web services.

Summary

  • REST API: A set of conventions and principles for building web services using HTTP, focusing on stateless communication, resource manipulation, and a uniform interface.
  • HTTP: A protocol used for transmitting data over the web, providing the foundation for REST APIs but also supporting other types of web communication.
  • Key Difference:
  • REST API: An architectural style that uses HTTP to perform operations on resources.
  • HTTP: The underlying protocol that REST APIs and other web technologies use to transmit data.

Follow-up Question

  1. Can a web service be RESTful without using HTTP?
  2. Answer: Technically, REST is an architectural style that could be implemented over other protocols, but in practice, RESTful services are almost always implemented over HTTP because of its ubiquity and the fit between REST principles and HTTP methods.