I have left Java and have been coding in Node and other technologies. But I would like to know "why developers are liking Play framework" these days? Some are even saying Play framework can be a strong competitor to Node.js because it also features some kind of event driven programming..
What's your opinion?
Play framework is written in Scala which runs on the JVM, not Java although you can mix Scala with Java and vice versa.
Using Scala gives you the benefits of using Scala Actors which is similar to NodeJS' event loop, but with the added benefit that it can also thread if you need to squeeze more performance out of the system and saturate all the cores.
Play was nice when server-side rendering was still the way to go, these days the web is moving towards client-side rendering and static pages, so Play is less relevant than it used to be. If you're building pages that needs to be rendered server-side for SEO purposes, Play is a great alternative to JSP (and JSF which is just horrible)
Edit: It's been a while since I looked at Play, I see you can use Play framework for its controllers in a similar way you can do with Spring MVC. If using Play just for its Controllers, I reckon it should be possible to get similar performance levels as with Vert.X due to its reactive nature (but with the extra overhead of supporting server-side rendering of pages which I personally don't use anymore). I'll dig around for some performance comparisons.