Async Python

HTTP Clients

Async HTTP Clients

Most AI APIs are accessed via HTTP. Let's learn to make efficient async HTTP requests.

HTTPX (Recommended)

Modern, async-first HTTP client:

import httpx

async with httpx.AsyncClient() as client:
    response = await client.post(url, json=data)

Key Features

  • Async support — Native async/await
  • Streaming — Handle streaming responses
  • Timeouts — Prevent hanging requests
  • Retries — Handle transient failures

Best Practices

  • Use context managers (async with)
  • Set reasonable timeouts
  • Handle exceptions properly
  • Reuse client instances

Try It Yourself

Run this code example to practice what you've learned.

example.py
1import asyncio
2# Install with: pip install httpx
3
4# Simulated HTTP client behavior for demo
5class MockAsyncClient:
6    """Mock client for demonstration."""
7    
8    async def __aenter__(self):
9        return self
10    
11    async def __aexit__(self, *args):
12        pass
13    
14    async def post(self, url: str, json: dict, timeout: float = 30.0):
15        await asyncio.sleep(0.5)  # Simulate network
16        
17        class Response:
18            status_code = 200
19            def json(self):
20                return {
21                    "choices": [{
22                        "message": {
23                            "content": f"Response to: {json.get('messages', [{}])[-1].get('content', '')}"
24                        }
25                    }]
26                }
27        return Response()
28
29async def chat_completion(messages: list[dict]) -> str:
30    """Make a chat completion request."""
31    async with MockAsyncClient() as client:
32        response = await client.post(
33            "https://api.openai.com/v1/chat/completions",
34            json={
35                "model": "gpt-4",
36                "messages": messages
37            },
38            timeout=30.0
39        )
40        
41        if response.status_code == 200:
42            data = response.json()
43            return data["choices"][0]["message"]["content"]
44        else:
45            raise Exception(f"API error: {response.status_code}")
46
47async def main():
48    messages = [
49        {"role": "system", "content": "You are helpful."},
50        {"role": "user", "content": "Hello!"}
51    ]
52    
53    response = await chat_completion(messages)
54    print(f"AI: {response}")
55
56asyncio.run(main())