HTTP Persistent Connection

HTTP persistent connection, also known as HTTP keep-alive or connection reuse, involves using a single TCP connection for multiple HTTP requests/responses instead of opening new connections for each pair. This method is employed in both HTTP/1.0 (unofficially through an extension) and HTTP/1.1 (officially, with all connections considered persistent unless specified otherwise). It offers several advantages, including reduced latency, CPU usage, network congestion, and enhanced HTTP pipelining. However, it can lead to resource allocation issues on the server if connections are not properly closed. Modern web browsers and Python’s requests library support HTTP persistent connections.

Overview

• Definition: A method to use a single TCP connection for multiple HTTP requests/responses.
• Also Known As: HTTP keep-alive, connection reuse.

Versions

• HTTP/1.0: Unofficially implemented through an extension.
• HTTP/1.1: Officially supports persistent connections as a default.

Advantages

1. Reduced Latency: Fewer delays in communication.
2. Lower CPU Usage: Less processing power required for connection setup and teardown.
3. Decreased Network Congestion: Fewer connections lead to less network traffic.
4. Enhanced HTTP Pipelining: Efficient request/response processing.

Disadvantages

• Resource Allocation Issues: Potential server problems due to improperly closed connections.

Support

• Modern Web Browsers: Generally support HTTP persistent connections.
• Python’s requests Library: Also supports this feature.

For more detailed information, visit the Wikipedia article.