Caches and Message Queues
This chapter, though brief, might be one of the most important in this book. It surveys two technologies—caches and messages queues—that have become fundamental building blocks for services under heavy loads. The book here reaches a turning point here. The previous chapters have explored the sockets API and how Python can use primitive IP network operations to build communication channels. All of the subsequent chapters, as you will see if you peek ahead, are about particular protocols built atop sockets—how to fetch documents from the World Wide Web, send e-mail, and submit commands to remote servers.