• Introduction
  • How Does an API Qualify as RESTful?
  • 1. Use of Standard HTTP Methods
  • 2. Uniform Data Format
  • 3. Client-Server Separation
  • 4. Statelessness
  • 5. Resource-Based Architecture
  • The Internet as an Example of REST
  • Conclusion

Introduction

This article dives into building a REST API. You might have thought that now it is time to rest, but actually, it is time to learn about Representational State Transfer (REST) APIs! We start by understanding how to build a RESTful API because this is important for modern web development. So let's go through the major principles that define REST architecture.

How Does an API Qualify as RESTful?

One of the classic interview question you could be asked is: What makes an API **RESTful? The answer lies in a few cardinal rules governing the design and functionality of REST APIs:

1. Use of Standard HTTP Methods

RESTful APIs depend on standard HTTP methods to take actions against resources. Some of the familiar HTTP verbs are as follows:-

• GET - This is used to retrieve data from a server.

• POST - This is used when one wants to send data to a server with the intention of creating a new resource.

• PUT - Updates an existing resource.

• PATCH Partially update a resource.

• DELETE - Remove a resource from the server.
  Applying these methods appropriately can help a client intuitively interact with the API.

2. Uniform Data Format

RESTful API should always respond with a consistent data format, for example, JSON (JavaScript Object Notation) or XML (eXtensible Markup Language). Such uniformity guarantees that data returned from API could be easily parsed and used by clients, which is an essential aspect in communication.

3. Client-Server Separation

In RESTful architecture, the client and server are completely separated; they communicate over a network but never reside within the same system. This separation of both sides allows each side to evolve independently, hence developing scalable applications. For example, one can upgrade or change a client without updating or changing server-side code.

4. Statelessness

Statelessness is one of the base principles of REST APIs. Every request from a client to the server should contain all the contextual information regarding the request, so that it understands it and processes it accordingly. No state or information concerning the client is maintained by the server between requests. This makes each request independent and allows for scalability while easing server implementation. For example, if a client were to make a request, the server does not need to remember previous interactions; thus, it will process different requests simultaneously with effectiveness.

5. Resource-Based Architecture

RESTful APIs are based on resources. In this context, resources are the 'things' that can be identified and manipulated through a Unique Resource Identifier URI,also known as URL. Any given URL identifies the address of a specific resource so that the client can locate, access, and work with it easily. This is the essence of RESTful design.

The Internet as an Example of REST

You may recognize that these principles closely resemble how the internet operates. One of the most successful implementations of RESTful architecture is the World Wide Web, in which:-

• Resources are identified by URLs.
• Interactions are stateless using standard HTTP.
• Responses come in JSON, XML, HTML, etc.
• It uses the client-server architecture : clients (users in browsers) request resources stored on servers.
• Every web request is itself stateless; everything is contained in the request for processing.

Conclusion

Understanding REST APIs principles is a very important step for anyone in tech especially if you are looking to develop modern web applications. By adhering to the REST architecture, developers can create robust, scalable, and efficient APIs that effectively communicate with clients.