Application Programming Interface (API)

What are Application Programming Interfaces?

Interacting with a computer application requires some form of interface. When two computer applications need to interact, they do so using an Application Programming Interface (API).

API Architectures

More on API Architectures.

Representational State Transfer (REST)

A REST API call follows four steps:

1. The client sends a request.
2. The server processes the request.
3. The server sends the response.
4. Data is transferred. The REST API architecture is by far the most commonly used and powers much of the modern internet.

Request Methods

• GET - retrieves a resource
• POST - submits new data to the server
• PUT - updates existing data
• DELETE - removes data

These request methods map to CRUD operations.

Key Points on REST

• Maps resources to URLs, and uses HTTP to methods to manipulate those resources.
• For example /users/{userID} to get a user or POST /user/{userID}/booking to create a booking.
• If you’re returning large results, you’ll want to use pagination.

More on REST APIs.

Server Sent Events (SSE)

Websockets

gRPC

API Design

More on API Design.

Microservices

API Gateways

Pagination

Rate Limiting