I'm trying to avoid people needing to even read the book. It's the difference between rolling your own WebSockets or using Pusher, for example. Some people want things to just work.
You're basically deploying a thing that'll send http requests to another server which then executes specific tasks. So you've essentially replaced hubot with a web application on the end users servers.
What is the difference?
The end user still needs to run something on their servers to actually do anything for their custom commands, which is essentially what hubot scripts do, which is what my book is teaching people about.