Drew DeVault has just released a (mostly complete) book on the Wayland display-server
protocol under the Creative Commons CC-SA license. “This book
will help you establish a firm understanding of the concepts, design, and
implementation of Wayland, and equip you with the tools to build your own
Wayland client and server applications. Over the course of your reading,
we’ll build a mental model of Wayland and establish the rationale that went
into its design. Within these pages you should find many ‘aha!’ moments as
the intuitive design choices of Wayland become clear, which should help to
keep the pages turning.” For those who would rather peruse (or
contribute to) the Markdown source, it’s available here.

Source: LWN.net – The Wayland Protocol