Introduction to REST APIs

 

Introduction to REST APIs 

What is an API?

An API (Application Programming Interface) is a bridge that allows two software systems to communicate.

Example:

  • A mobile app sends a request to a server.

  • The server processes it.

  • The server sends back data (usually JSON).

You use APIs daily:

  • Payment gateways

  • Weather apps

  • Social media feeds

  • E-commerce platforms

What is REST?

REST (Representational State Transfer) is an architectural style for designing networked applications over HTTP.

It was introduced by Roy Fielding in 2000.

REST is:

  • Lightweight

  • Scalable

  • Simple

  • Stateless

REST Architecture Principles

1️⃣ Stateless

Each request must contain all necessary information.
Server does not store client session data.

2️⃣ Client-Server

Frontend and backend are independent.

3️⃣ Cacheable

Responses must define if they can be cached.

4️⃣ Uniform Interface

Consistent URL design and HTTP usage.

HTTP Methods in REST

Method                            Purpose
GET                        Retrieve data
POST                        Create new resource
PUT                        Replace resource
PATCH                        Partial update
DELETE                        Remove resource

Example:

GET /users/
POST /users/
GET /users/1/
DELETE /users/1/

Why REST Became Popular?

  • Uses HTTP
  • Supports JSON (lightweight)
  • Works well with web & mobile
  • Easy to scale

 REST vs SOAP

Before REST, SOAP was widely used.

Feature                REST                    SOAP
Protocol                            HTTP                    HTTP, SMTP
Format                JSON, XML                    XML
Speed                Fast                    Slower
Learning Curve                Easy                    Complex

When to Use REST?

  • Web Applications

  • Mobile Apps

  • Microservices

  • Public APIs

When SOAP is Better?

  • Banking systems

  • Enterprise security-heavy systems

  • Formal contracts (WSDL)



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