HTTP Keep-Alive

Follows HTTP 04: Routing and Response, which taught the server to answer one question and then hang up, and hands off to HTTP Server: Concurrency.

Before you start. This series builds a small copy of a web server - a program that sits waiting on the network, reads one request (one question, like “give me this page”), and writes back an answer. So far the toy can already tell exactly where one request ends and the next would begin (HTTP 03: Frame The Body), and it can read a request, work out what it is asking for, and answer it once before closing the line (Parse The Request (HTTP), HTTP 04: Routing and Response). If the handshake that opens a connection is unfamiliar, TCP vs UDP, and the 3-way handshake in Networking shows it in one read.