Since this book is aimed at the cutting edge of Spring Boot 2.0 and its Reactive Streams support, we have to pick something a little more up to date than JPA. The JPA spec doesn't cover reactive programming. Hence, its APIs are not reactive. However, MongoDB has reactive drivers, and will be perfect.
To get going, we need to install the latest version of MongoDB 3.4 (for reactive support).
If you're using macOS X, installing MongoDB is as simple as this:
$ brew install mongodb ==> Installing mongodb ==> Downloading https://homebrew.bintray.com/bottles/mongodb-3.4.6.el_capitan.bottle.tar.gz ########################################################## 100.0% ==> Pouring mongodb-3.4.6.el_capitan.bottle.tar.gz ...
