>> Is there any way to send message for all users in web app?
Not in NetTalk 7.
There's no "connection" between the server and the client, so there's no way to "push" information to the "users".
I'm _planning_ to implement Server-Side-Events in NetTalk 8 which may or may not do what you want. As usual though, no promises until I actually have something ready.
Cheers
Bruce