I built a fairly complex app in vert.x a few years back. If you don't start with a promises library off the bat, you end up in a callback hell not unlike node.js.<p>You also realize very quickly how synchronous many of the Java libraries for things like databases, redis, etc are. The ecosystem just isn't built to work like that, but that's not the fault of the vert.x guys.
Vert.x indeed looks pretty cool. But I found it a little bit weird that they used the term "reactive" in the title, but I'm not sure what the "reactive" is referring to: maybe Reactive Extensions, or at least RxJava? which should be perfect with vert.x to solve the callback hell problem. Or they just use it as a generic term for async technology used in vert.x/node.js/tornado etc?
> Polyglot. You can use Vert.x with multiple languages. Vert.x doesn't preach about what language is best<p>Gradle should learn this lesson and also offer multiple languages for its build scripts, and more people might adopt it.