In casual parlance of terminology, Vert.x isn't really a library in the sense a dependency you pull in because it implements some specific functionality with a

In casual parlance of terminology, Vert.x isn't really a library in the sense a dependency you pull in because it implements some specific functionality with a handful of method calls. Vert.x "feels" more like a framework in the sense of giving your thought process and your application an architectural template and invites you to code in a style that it supports; but I also don't think 'framework' is a bad word. Realistically, Vert.x blurs the lines between a runtime, an event bus, a library, a framework, and a platform -- it's quite enjoyable to use, but despite their insistence to the contrary I don't think it's something that one should grab off the shelf and sprinkle into a larger product.