I've been developing the library to enable BLE MIDI feature on the Android devices from last year. The Apple Bluetooth Low Energy MIDI Specification(PDF) had revealed at December 2014. And finally, I implemented all of features on the specification.
Using this library, the app can connect with BLE MIDI devices, and BLE MIDI compatible iOS/Android/OS X apps. On the Android Lollipop, the app can act as BLE MIDI device.
Note:
This Apple's specification has not been approved by MIDI Manufacturers Association(MMA). I've asked about the specification to MMA at the past, but it was under discussion with MMA members.
The MMA's official release version's specification might be different from Apple's one.
The library's features
With this library, the Android can provide BLE MIDI Central / Peripheral features.
BLE MIDI Central feature
The Android app can host BLE MIDI devices. The app can receive MIDI messages from BLE MIDI devices, and send MIDI messages to them.
This feature requires Android KitKat(4.4 / API Level 19) or later.
BLE MIDI Peripheral feature
The Android app can pretend as BLE MIDI device. The application on the another machine(Android / iOS / OS X) can connect with the Android app.