Today i got the update about this new project from JBoss.
I am not sure but it description says its a gwt messaging framework which can be used for client - server communication.
Is it of any relevance for Vaadin , how can it be compared with vaadin.
There is little to compare: Errai is a communication framework for GWT. It can be used for passing messages back and forth between server and client. Thus this has little overlap with Vaadin. Instead it overlaps with the RPC implementation in GWT itself. And even that is not used in Vaadin.
That said - there are couple of connection points. One could probably use Errai to create a real-time push channel for a Vaadin component. Or we could even consider using Errai for implementation of the “next generation” communication inside Vaadin.