An Overview of HTTP/2: Features, Mechanisms, and Performance Experiments

HTTP/2 aims to make web applications faster, simpler, and more robust by eliminating many of the performance hacks required for HTTP/1.1 and by leveraging TCP characteristics more effectively.

The protocol introduces a binary framing layer that splits messages into streams, each composed of frames, allowing many concurrent bidirectional byte streams over a single TCP connection. Frames are binary‑encoded, reducing parsing overhead and enabling out‑of‑order delivery.

Key features include:

Multiplexing : multiple streams share one connection, reducing handshake latency and overall packet count.

Header compression via the HPACK algorithm, which uses a static and dynamic index table plus Huffman coding to shrink header size.

Request priority : each HEADERS frame can carry a priority value, allowing servers to allocate resources preferentially.

Server push : servers may proactively send resources after a PUSH_PROMISE frame, subject to client acceptance.

Flow control : DATA frames are subject to window‑based flow control, similar to TCP, to prevent a single stream from monopolizing the connection.

Tools such as Chrome's chrome://net-internals/#http2, protocol columns in developer tools, and various browser extensions help inspect HTTP/2 traffic.

Experimental verification using a Node.js server compared HTTP/2, HTTPS, HTTP/1.1, and SPDY when loading ten images. Results showed clear benefits of multiplexing, while header compression impact on load time was less pronounced in a local‑only test.

The article concludes that HTTP/2 provides substantial performance improvements, especially in reducing latency and connection overhead, though real‑world gains depend on network conditions and proper use of its features.