I'm going to spoil: Practical Microservices will cover
synchronous communication with
both HTTP and AMQP (RabbitMQ and friends), as well as async with AMQP.
Among other benefits sync over AMQP provides is the fact that you don't really need a service discovery mechanism because interested service will find & serve your request itself. It also means that you won't need to put the services behind a firewall or implement some sort of inter-service auth (when firewall isn't an option, read: Heroku), because nothing is exposed to the web.
Will definitely get into it more deeply in Practical Microservices. Stay tuned!
