Service Discovery Application Profile (SDAP)

SDAP describes how an application should use SDP to discover services on a remote device.

Usage Scenarios

SDAP describes how an application should use SDP to discover services on a remote device. It illustrates several approaches to managing the device discovery via Inquiry and Inquiry Scan and service discovery via SDP. The ideas contained in the SDAP specification augment the basic specifications provided in GAP, SDP, and the basic processes of device discovery. The use cases for SDAP are intended to encompass the majority of service discovery scenarios associated with all profiles and devices.

Example Products

Here are a few examples of the types of devices that you might find using the SDAP:

• PC
• Laptop
• Mobile phone
• PDA
• Printer/fax
• Headset

Getting Technical

As required by the GAP, any Bluetooth enabled device should be able to connect to any other Bluetooth enabled device. Based on this, SDAP requires that any application be able to find out what services are available on any Bluetooth enabled device to which it connects. The profile handles the search for known and specific services as well as searches for general services. SDAP involves an application, the service discovery user application, which is required in a Bluetooth device for locating services. This application interfaces with the SDP that sends and receives service inquiries to and from other Bluetooth enabled devices. SDAP is dependent on and re-uses parts of the GAP.

The SDAP defines two roles, Local Devive (LocDev) and Remote Device(s) (RemDev(s)).

• Local Device (LocDev) – The device that initiates the service discovery procedure.
• Remote Device(s) (RemDev(s)) – Any device that participates in the service discovery process by responding to the service inquiries generated by a LocDev.

The service discovery user application (SrvDscApp) in a local device (LocDev)interfaces with the Bluetooth SDP client to send service inquiries and receive service inquiry responses from the SDP servers of remote devices (RemDevs)BT_SDP_spec:[7]. SDP uses the connection-oriented (CO) transport service in L2CAP, which in turn uses the baseband asynchronous connectionless (ACL) links to ultimately carry the SDP PDUs over the air.

Service discovery is tightly related to discovering devices, and discovering devices is tightly related to performing inquiries and pages. Thus, the SrvDscApp interfaces with the baseband via the BT_module_Cntrl entity that instructs the Bluetooth module when to enter various search modes of operation.

Need more? View the Service Discovery Application Profile (SDAP).