We'll see how this stuff actually works in practice pretty soon, but as this is more than just a chunk of code to run on a device, what exactly is going to be "

We'll see how this stuff actually works in practice pretty soon, but as this is more than just a chunk of code to run on a device, what exactly is going to be "open" here? A formal standard that can be implemented and used by other platforms, both on the device and server side, would be great. But Apple's last promise to make something they developed "open" (iMessage as a standard) evaporated and has since been completely proprietary.