WebAPI/WebBluetooth
WebBluetooth
Goals
The aim of WebBluetooth is to establish a DOM API to set up and communicate with Bluetooth devices. This includes setting properties on adapters and devices, scanning for devices, bonding, and socket initialization for audio and communication.
Future versions may include OBEX and profile support.
B2G Needs
Boot2Gecko is the main consumer of WebBluetooth for the moment. Most operating systems already provide a configuration layer for bluetooth, and we do not plan on overriding that. However, B2G will require its own settings and initialization code, so the focus of the API is on that platform for the time being.
Implementation Specifics
For communicating with the bluetooth adapter and devices on B2G, we will be using the DBus message system. This allows us to easily access all parts of the bluetooth system on B2G based platforms, without having to worry about GPL licensing issues.
DOM API
Manager
interface nsIDOMBluetoothManager : nsIDOMEventTarget
{
readonly attribute bool enabled;
nsIDOMDOMRequest setEnabled(in boolean enabled);
nsIDOMBluetoothAdapter getDefaultAdapter();
};
Adapter
interface nsIDOMBluetoothAdapter : nsIDOMEventTarget {
bool startDiscovery(); // ret: false if bluetooth is not enabled void stopDiscovery(); nsIDOMBluetoothDevice getDevice(DOMString address); // Like a device creator bool connect(in nsIDOMBluetoothDevice device); void disconnect(in nsIDOMBluetoothDevice device); readonly attribute DOMString address; readonly attribute unsigned long class; readonly attribute bool enabled; readonly attribute bool discovering; readonly attribute DOMString name; // Set custom device name readonly attribute bool discoverable; // Set to false if this device would not like to be discovered readonly attribute unsigned long discoverabletimeout; // Unit: sec
// Since setting properties can require IPC calls based on the // bluetooth implementation, set properties via DOMRequests to // handle callbacks. nsIDOMDOMRequest setName(DOMString name); nsIDOMDOMRequest setDiscoverable(bool discoverable); nsIDOMDOMRequest setDiscoverableTimeout(unsigned long timeout); attribute nsIDOMEventListener ondevicefound; // Fired when discoverying and any device is discovered. attribute nsIDOMEventListener ondevicedisappeared; // Fired when any device is out of discoverable range. attribute nsIDOMEventListener ondeviceconnected; // Fired when a remote device is connected attribute nsIDOMEventListener ondevicedisconnected; // Fired when a remote device is disconnected
};
Device
interface nsIDOMBluetoothDevice : nsISupports
{
readonly attribute DOMString address;
readonly attribute unsigned long class;
readonly attribute bool connected;
readonly attribute DOMString name;
readonly attribute jsval serviceUuids; // DOMString[]
};
DBus Usage and Licensing
Bluetooth on Linux and B2G is accessed via the Bluez bluetooth stack. This stack is GPL, and the libraries that come with it to access bluetooth sockets are also GPL. To remove the licensing issues involved with this, the DBus communications layer is used to provide an IPC route for bluetooth related code. The WebBluetooth API (on Linux and B2G) will use DBus to keep the code compatible with the MPL.
DBus on Linux and Android
There are many ways to access DBus from code. On linux, gecko already uses the glib bindings for battery information on linux (UPowerClient.cpp). Android uses the low level DBus bindings, mainly made for writing language binding systems. This tends to create very complicated code, which even the DBus maintainers warn developers off of (See DBus API Documentation).
On B2G, we'd like to avoid tying glib into the gecko build. We'll be using the dbus-c++ library on that platform in order to keep the dbus code simple and clean.
Links
Bugzilla
External
- DBus Intro
- Android Bluetooth Manual
- Android Bluetooth Architecture
- Bluetool C++ Bluez Interaction Code
- Android Bluetooth FAQ
