At saxsys I'm part of a team that is developing a digital scrumboard with JavaFX. One of the key features is the instant synchronization of the UI state between different boards over the network. When you drag a task note at one of the boards it moves instandly on the other board too.
For this feature we had developed a small library and I'm very pleased that we can now release this library as a free open source project called "SynchronizeFX". You can find the code at github: https://github.com/saxsys/SynchronizeFX.
The key idea is that we synchronize models that are build up on JavaFX's Properties. At the moment the synchronization over the network is done with websockets but other technologies are possible too.