The Web has an incredible amount of material. Many web services, such as GitHub and YouTube, provide an application programming interface (API) for third-party apps to access their data. The REST architectural style is one of the most widely used approaches to develop APIs. Not only can Python be used to create your own Python REST APIs, but it also offers excellent capabilities for retrieving data from REST APIs.
REST Architecture:
REST stands for REpresentational State Transfer and API stands for Application Program Interface. REST is a software architecture style that outlines a standard for networked client-server communications. REST offers a set of guidelines for software architecture that support system stability, simplicity, scalability, and performance.
REST defines the following architectural constraints:
⦁ Stateless: During client requests, the server won’t keep track of any information.
⦁ Client-server: To enable independent development, the client and server need to be separated from one another.
⦁ Cacheable: The information that the client or the server retrieves from the server should be able to be stored in a cache.
⦁ Uniform interface: The server will offer a consistent interface that allows users to access resources without having to specify how they are represented.
⦁ Layered system: Through intermediary layers like a load balancer or proxy, the client can obtain resources on the server.
⦁ Code on demand (optional): The server may transfer code to the client that it can run, such as JavaScript for a single-page application.
REST web service:
A REST web service is any online service that follows REST architecture requirements. These web services use an API to expose their data to the outside world. REST APIs allow you to access web service data using public web URLs.
For example, here’s one of the URLs for GitHub’s REST API: https://api.github.com/users/
This URL allows you to access information about a specific GitHub user. You access data from a REST API by sending an HTTP request to a specific URL and processing the response.
HTTP Methods:
REST APIs use HTTP methods such as GET, POST, and DELETE to detect which actions to take on the resources of the web service. A resource is any data available in the web service that can be accessed and manipulated by making HTTP requests to the REST API.
While there are many HTTP methods, the five methods listed below are the most commonly used with REST APIs:
GET – Retrieve an existing resource.
POST – Create a new resource.
PUT – Update an existing resource.
PATCH – Partially update an existing resource.
DELETE – Delete a resource.
Status Codes:
An HTTP response is returned by a REST API after it has received and processed an HTTP request. This response contains an HTTP status code. Applications can verify the status code and take action based on the response from the API when they send requests. These might involve resolving errors or informing the user of a successful outcome. Status codes are numbered based on the category of the result:
2XX – Successful operation
3XX – Redirection
4XX – Client error
5XX – Server error
Building APIs:
Building APIs involves several key steps to ensure they are well-designed, efficient, and easy to use. Here’s a basic outline of the process:
⦁ Identify Resources: Determining which resources the API will manage is the first step in creating a REST API. These resources, like customers, events, or transactions, are frequently described as plural nouns. You will develop a list of nouns that characterize the various types of data that users can manipulate through the API as you discover the various resources in your web service.
⦁ Define Your Endpoints: Once you’ve identified the resources in your web service, you’ll want to use these to define the API endpoints. Here are some example endpoints for a transactions resource you might find in an API for a payment processing service:
HTTP method API endpoint Description
GET /tasks – Get a list of tasks.
GET /tasks/ – Get a single task.
POST /tasks – Create a new task.
PUT /tasks/ – Update a task.
PATCH /tasks/ – Partially update a task.
DELETE /tasks/ – Delete a task.
In the below section, we’ll explore various data formatting options for REST API.
⦁ Format for Data Interchange: Two popular options for formatting web service data are XML and JSON. Traditionally, XML was very popular with SOAP APIs, but JSON is more popular with REST APIs.
Here’s the book formatted as JSON :
{
“title”: “Python Basics”,
“page_count”: 635,
“pub_date”: “2021-03-16”,
“authors”: [
{“name”: “David Amos”},
{“name”: “Joanna Jablonski”},
{“name”: “Dan Bader”},
{“name”: “Fletcher Heisler”}
],
“isbn13”: “978-1775093329”,
“genre”: “Education”
}
JSON stores data in key-value pairs similar to a Python dictionary. JSON supports nesting data to any level, so you can model complex data.
⦁ Design Success Responses: After you’ve chosen a data format, you’ll need to decide how you’ll handle HTTP requests. Your REST API should only return responses that follow a standard format and contain the correct HTTP status code.
To start things off, take a look at a GET request to /fruits/1, which returns a single fruit value:
GET /fruits HTTP/1.1
Host: api.example.com
This HTTP request is made up of four parts:
* GET is the HTTP method type.
*/fruits/1 is the API endpoint.
*HTTP/1.1 is the HTTP version.
*Host: api.example.com is the API host.
This HTTP request queries the API for fruit 1. Here’s the response:
HTTP/1.1 200 OK
Content-Type: application/json
{
“id”: 1,
“fruit”: “Apple”,
“quantity”: “15”,
“color”: “Red”
}
⦁ Design Error Responses: It’s important to establish a standardized format for error responses in your REST API to effectively communicate issues when requests fail. These responses should provide a clear description of the encountered error alongside the relevant status code.
HTTP/1.1 404 Not Found
Content-Type: application/json
{
“error”: “The requested resource was not found.”
}
Now, let’s dive into creating a basic RESTful API using Python and Flask, a lightweight web application framework. First, ensure Flask is installed:
pip install Flask
Next, let’s create a simple Flask application:
from flask import Flask, jsonify
app = Flask(name)
@app.route(‘/api/hello’, methods=[‘GET’])
def hello():
return jsonify({‘message’: ‘Hello, World!’})
if name == ‘main’:
app.run(debug=True)
Save this code in a file named app.py. Run the application using:
python app.py
Now, you can access the API at http://127.0.0.1:5000/api/hello, and it will respond with a JSON message: {“message”: “Hello, World!”}.
Consuming RESTful APIs:
Python provides several libraries for consuming RESTful APIs, such as requests and http.client. Let’s demonstrate how to make a GET request to an external API using the requests library:
import requests
url = ‘https://api.example.com/data’
response = requests.get(url)
if response.status_code == 200:
data = response.json()
print(data)
else:
print(‘Failed to fetch data:’, response.status_code)
Replace ‘https://api.example.com/data’ with the URL of the API you want to consume.
Conclusion:
In conclusion, REST APIs are everywhere. Implementing a REST API involves defining clear and consistent endpoints, choosing appropriate HTTP methods for CRUD operations, and establishing standardized data formatting and error handling practices. By following RESTful principles, such as using resource-based URLs and stateless communication, developers can create APIs that are intuitive, scalable, and interoperable. Overall, a well- designed REST API simplifies integration, promotes developer productivity, and enhances the overall user experience.
