Note especially this comment:
You should always set the provided on vaadin-client-compiler as it does not need to (and should not be) deployed. Then you will avoid Jetty (and other dependency) version conflicts.
but the problem still exist, no idea to me to solve the problem. now i am trying to run my war on other Apps Server, since i read many problem with websocket on tomcat. do you have any suggestion ?
as of your suggestion, I looked back all the ticket from 7.6.0 alpha2 upto 7.6.0 alpha 7, yes many ticket regarding push was solved. I will go and try using 7.6.0 beta1 hopefully will solve my problem.
now, I had sucesfull running push using transport = Long Pooling (7.5.9) but new problem is coming up. all the application geeting slow, significantly slow.
I will trying using WebSocket &.7.6.0 beta1 first and will be skip slow problem 7.5.9 slow performance.
thank you very much for you suggestion
regards
Nengah