Bluetooth Profiles : Service Discovery Application Profile (SDAP)

After a Bluetooth device discovers another Bluetooth device and pair, the device will have to search for services supported by another device before starting a service. If a particular service is supported by both Bluetooth devices, the service can be performed. If it is only supported by one device, it can't be performed. The process to discover available services in another Bluetooth device is facilitated by Service Discovery Application Profile.

For example a desktop PC and a mobile phone are both set discoverable. After the PC finds the mobile phone and pair, it searches for available services in the mobile phone. If the PC wants to use the mobile phone as a modem that will connect it to the Internet, then the associated profile that's DUN must be present at the PC and the mobile phone.

Figure: Service Discovery Application Profile
After finding another Bluetooth device (i.e. a mobile phone),
a Bluetooth device (i.e. desktop PC) searches for available services in the target device.

Two screenshots below are the results of service discovery.

Click the thumbnail pictures above to see the examples of Bluetooth services supported by a Bluetooth-enabled computer and a Bluetooth cellphone.

A typical Bluetooth device is not designed to support all Bluetooth profiles, instead it usually supports the device specific functions. By supporting only specific functions, the design will be simpler and the connection setup will be faster. For example, a Bluetooth headset only supports headset profile, a Bluetooth printer only supports Hardcopy Cable Replacement Profile (HCRP) or Basic Printing Profile (BPP). Meanwhile, a Bluetooth-enabled computer (PC) usually supports more profiles.

Back to Bluetooth Profiles.