What are the limits of vert.x handler<> and why futur is used instead !
What is the difference between the handler interface and futur ?
In Vert.x, a Handler is an asynchronous callback function. The only "limitation" it has is that it shouldn't contain blocking code.
A Future is a result of an asynchronous function.
Future is not used instead of Handler. You can have a handler that doesn't return a future, or you can have a Future that is not returned by a handler.