HTTP: The Definitive Guide

Layer 1: Messaging

Let’s take a closer look at the three layers of HTTP-NG, starting with the lowest layer. The message transport layer is concerned with the efficient delivery of messages, independent of the meaning and purpose of the messages. The message transport layer provides an API for messaging, regardless of the actual underlying network stack.

This layer focuses on improving the performance of messaging, including:

• Pipelining and batching messages to reduce round-trip latency

• Reusing connections to reduce latency and improve delivered bandwidth

• Multiplexing multiple message streams in parallel, over the same connection, to optimize shared connections while preventing starvation of message streams

• Efficient message segmentation to make it easier to determine message boundaries

The HTTP-NG team invested much of its energy into the development of the WebMUX protocol for layer 1 message transport. WebMUX is a high-performance message protocol that fragments and interleaves messages across a multiplexed TCP connection. We discuss WebMUX in a bit more detail later in this chapter.