As I’ve been learning Python and building out my own APIs, I’ve become interested in the differences between RESTful APIs vs. REST APIs. Generally speaking, REST (Representational State Transfer) and RESTful are terms that are often used interchangeably. However, they do represent slightly different concepts. I figured I’d do a deeper dive to dissect these distinctions and explain how they apply when building APIs using Python.

What is an API?

Just to give some background, an API (Application Programming Interface) serves as an intermediary, or middleman, between two applications so that those applications can communicate with one another and provide each other with relevant data. For example, a ride sharing service might use a Google Maps API in order to provide the ride sharing app with relevant data like traffic conditions or estimate times of arrival. Essentially, an API just allows two apps to “talk” to one another.

What is REST?

REST (Representational State Transfer) is an architectural style for designing networked applications. It was developed by Roy Fielding during his doctoral research at UC Irvine, designed to set a standard for web apps to structure their URLs. REST uses a stateless, client-server communication model, where each request from the client to the server must contain all the necessary information to understand and process the request.

REST APIs use standard HTTP methods like GET, POST, PATCH, and DELETE to perform CRUD (Create, Read, Update, and Delete) operations. This makes REST APIs highly scalable and efficient, as each request is independent and doesn't rely on a stored state on the server.

In practice, here’s generally how you might configure a REST API using Python.

What is RESTful API?

RESTful is an adjective used to describe web services that conform to the REST architectural style. A RESTful API, then, is an API that adheres the principles laid about by the REST architecture. This strict adherence leads to a more standardized and predictable web API behavior, making it ideal for large-scale and complex applications.

RESTful APIs also consider cacheability as a core feature, using it to significantly boost the performance and scalability of web services. They prefer a rigorous, multi-layered architecture, and they consistently maintain a standard interface. They also strictly implement statelessness and avoid using RPC (Remote Procedure Call) style interactions, sticking instead to a resource-based approach.

Understanding the Difference between REST and RESTful.

We can create our own APIs using REST, which we now know is a software architecture, while RESTful can be though of as an adjective that describes the software that we’re building that uses the REST architecture. Going back to our earlier example of the ride sharing service, we can think of the Google Maps API using REST, while considering the architectural configuration as RESTful (because it’s using REST!).

While both REST and RESTful APIs aim to provide a standardized way of interacting with resources over the internet, they differ in their level of adherence to the principles of REST.

REST is an architectural style that guides the design of networked applications. It includes principles like statelessness, client-server communication, and a uniform interface among others. However, not all APIs that claim to be RESTful strictly adhere to these principles.

On the other hand, a RESTful API is an API that strictly adheres to the principles of REST. This means that it is stateless, uses standard HTTP methods for CRUD operations, and provides a uniform interface. Furthermore, a RESTful API can leverage cacheability, which can significantly enhance performance and scalability.

In essence, while REST is a set of constraints or guidelines, RESTful refers to an API that adheres to these constraints. Therefore, when we’re comparing RESTful to REST, it's important to note that RESTful APIs are simply REST APIs that adhere more closely to the REST principles.

How Can We Build APIs in Python?

In Python, you can build both REST and RESTful APIs using various libraries and frameworks like Flask and Django.

For example, here's what a simple REST API endpoint in Flask might look like:

from flask import Flask, jsonify, request
app = Flask(__name__)

@app.route('/items', methods=['GET'])
def get_items():
    # Logic to fetch items goes here
    items = ["item1", "item2"]
    return make_response(jsonify(items), 200)

In this case, we're creating a GET endpoint /items that returns a list of items. This is a very basic example and doesn't fully embody the principles of a RESTful API. To create a truly RESTful API, we would need to ensure that our API adheres to all REST principles, including statelessness, cacheability, and a uniform interface. Just to give a general idea of the difference in code structure, we might instead create a Class in Flask to begin building out a RESTful API:

from flask import Flask, request, make_response, jsonify
from flask_restful import Api, Resource
import os

BASE_DIR = os.path.abspath(os.path.dirname(__file__))
DATABASE = os.environ.get(
    "DB_URI", f"sqlite:///{os.path.join(BASE_DIR, 'app.db')}")

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = DATABASE
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.json.compact = False

db.init_app(app)
#use flask restful
api = Api(app)

class Items(Resource):
    def get_items():
        items = ["item1", "item2"]
        return make_response(jsonify(items), 200)

api.add_resource(Items, '/items')

In conclusion, while REST and RESTful APIs serve similar purposes, they differ in their level of adherence to REST principles. When developing APIs in Python, understanding these differences can help us build more efficient, scalable, and reliable applications.