When a Preference Editor such as the PCP or PMT makes changes to a user's preference set, or temporarily to a device's settings, we need some means by which they can signal a locally-installed Flow Manager about this change so that it can update the state of the system.
We've talked about different means--browser plugins, polling, and so on. My sense is that Web Sockets is likely the best cross-platform means we have available for communicating between the browser sandbox and applications running on the local device.
Here's an overview of my thinking on this topic so far:
Yura and Antranig have agreed to research the viability of using Web Sockets as a means for communicating between the PCP/PMT and the local flow manager.