REST APIs: The Significance of HTTP Methods (PUT, DELETE, POST, GET)

In the realm of RESTful APIs, a fundamental question arises: Why utilize multiple HTTP request types, such as PUT, DELETE, POST, and GET? It's important to understand that the purpose of REST goes beyond merely accessing data using the easiest method.

The Role of REST

The "REpresentational State Transfer" (REST) architecture provides a meaningful way to interact with data. When a REST request is made, it should immediately convey the intended action to be performed.

Example: GET Requests

Consider the following REST endpoint:

GET: /cars/make/chevrolet

This endpoint likely returns a list of Chevrolet cars. By using a GET request, the user explicitly specifies that they want to retrieve data, rather than modify it.

POST Requests: Creating Data

For creating new data, a POST request is typically used. For instance:

POST: /cars/
{ make:chevrolet, model:malibu, colors:[red, green, blue, grey] }

This POST request sends data to create a new Chevrolet Malibu with specified colors. The API is not necessarily tied to the underlying database structure, but instead provides a masking interface to protect the true data.

Idempotency and HTTP Methods

HTTP methods like GET, PUT, and DELETE follow the principle of idempotency. This means that repeated calls to these methods should result in the same server state. POST, on the other hand, is generally considered non-idempotent, as it can lead to different server states.

Implementing Idempotency

To ensure idempotency with POST requests, consider using the following pattern:

POST: /cars/oldest?action=delete

This endpoint explicitly defines the action to be performed (deletion), making it idempotent. In contrast, a request like:

Delete: /cars/oldest

could be potentially ambiguous and non-idempotent.

In conclusion, the use of specific HTTP methods in REST APIs is not arbitrary. They serve to convey the intended action (create, read, update, delete) and ensure the idempotency of the system. By adhering to these conventions, REST APIs provide a meaningful and structured approach to data manipulation and interaction.