Proximity Profile Implementation Details
To achieve a power-efficient design, device implementations must observe specific requirements to ensure that they remain compatible with Windows.
The following subtopics examine device-side requirements to enable efficient use of power, as well as describe a technique by which the connection state can be monitored.
Establishing a Connection
Windows 8.1 will automatically connect to a device when an application has a registered a handler for the GattCharacteristic.ValueChanged event. However the basic definition of the services included in the Proximity Profile does not contain any indicatable or notifiable characteristics. A device can add a service that contains an indicatable or notifiable characteristic to the services included in the Proximity Profile. This means that a proximity device must support at least one indicatable or notifiable characteristic value and an application must register at least one handler to a GattCharacteristic.ValueChanged event for the connection to be automatically established.
Detecting Loss of Connection
As mentioned in Bluetooth Proximity Profile, Windows 8.1 does not expose the RSSI value of Bluetooth connections. Consequently, apps cannot use the RSSI value to calculate the connection path loss. Instead, we recommend that a device tie its proximity to the link loss event.
Monitoring the connection state
Apps can monitor the connection state of GATT devices by using a PnpObjectWatcher and monitor the PnP "Connected" property of the service Device Object. This technique is demonstrated in the Bluetooth Generic Attribute Profile - Heart Rate Service sample.