Sorry for asking such a basic question, I have just come across Vaadin, it looks like a interesting way of creating web applications. I am very out of date of what the state of the art is these days, having last worked on web applications with classic ASP.NET, but do know about ASP.MVC.
As my background is C# and .NET I mostly get to work on systems that have a very large code base in C#, so just jumping ship to Java is not a good option.