The Python requests library has been a staple for developers who need to interact with HTTP servers in a straightforward and intuitive manner. However, the advent of HTTP/2 and the growing demand for asynchronous programming have pushed developers to seek enhanced functionalities that the basic requests library may not fully support. Let’s explore to what extent python-requests supports HTTP/2 and asynchronous calls and what alternatives or workarounds exist.

HTTP/2 Support in Python requests

The default behavior of the Python requests library is to support HTTP/1.1. Here's a brief exploration of the HTTP/2 protocol and its integration, or lack thereof, with requests.

Overview of HTTP/2

HTTP/2, as an upgrade from HTTP/1.1, offers several enhancements to improve performance:

• Multiplexing: Multiple requests and responses can be in flight at the same time without blocking each other, reducing latency.
• Header Compression: Reduces overhead by compressing headers.
• Server Push: Servers can preemptively send resources to clients.

HTTP/2 with requests

Out-of-the-box, python-requests does not inherently support HTTP/2. However, you can utilize the httpx library, which is designed to provide both HTTP/1.1 and HTTP/2 support, while maintaining a familiar API similar to requests.

Example with httpx

1import httpx
2
3client = httpx.Client(http2=True)
4response = client.get('https://example.com')
5print(response.status_code)

In the above example, setting http2=True allows httpx to utilize HTTP/2 when communicating with the target server.

Asynchronous Calls in Python requests

Asynchronous programming enhances performance by allowing a program to execute other code while waiting for operations like network requests to complete.

Asynchronous Support in requests

python-requests is naturally synchronous, meaning it blocks execution until a request completes. It neither natively supports asynchronous operations nor is it equipped with context managers to avoid blocking.

Workarounds for Asynchronous Behavior

Developers often turn to the aiohttp library for making asynchronous HTTP calls.

Example with aiohttp

1import aiohttp
2import asyncio
3
4async def fetch(url):
5    async with aiohttp.ClientSession() as session:
6        async with session.get(url) as response:
7            return await response.text()
8
9async def main():
10    html = await fetch('https://example.com')
11    print(html)
12
13# Run the event loop
14asyncio.run(main())

aiohttp integrates smoothly with Python's asyncio library, allowing developers to write non-blocking HTTP requests.

Comparison Table

Here's a comparison of different Python libraries for HTTP requests in terms of HTTP version support and asynchronous capability:

Additional Considerations

Migrating from requests to httpx

Transitioning to httpx from requests can be relatively seamless as it maintains a similar API. However, some nuances, particularly around handling asynchronous functions, should be understood. Having both HTTP/2 and asynchronous capability makes httpx a viable modern alternative to requests.

Use Cases for Asynchronous Requests

1. Web Scraping: Use asynchronous calls to scrape multiple pages efficiently.
2. API Requests: Handle large amounts of API interactions without waiting for each to complete sequentially.
3. File Downloads: Download multiple files concurrently without blocking the application.

Conclusion

While python-requests remains a favored library for its simplicity and reliability, limitations in HTTP/2 and asynchronous support necessitate looking towards libraries like httpx and aiohttp for more modern applications. By understanding these libraries' capabilities, developers can make informed decisions and write more efficient and responsive applications.