Bluetooth SDP

  • Search services on Bluetooth communication area
  • The list of services offered by device are stored in service records
    • Service records are maintained by SDP server
    • Only one SDP server can exists on a device
  • Services are categorized in classes
    • Describes the broader category in general e.g printer, color printer …
    • Defines the attibutes associated with the given type of service
    • Uniquely identified by 128-bit UUID
    • Service may be member of multiple classes
    • Profiles have their own classes.
  • Service attributes define characteristics of service

General discovery process

  • First inquiry is conducted to find devices in proximity
    • Inquiry is not necessary if services are requested from one particular device
  • Then connection for each device is formed to request services
    • ServiceSearchRequest
      • Find the service of interest
      • ServiceSearchResponse gives the record of searched
    • ServiceAttributeRequest
      • Find the service with certain attributes
    • ServiceSearchAttributeRequest
      • Combines the aforementioned tasks

Service attributes

  • Describe the essential characteristics of service
    • attribute identifier - 16-bit unsigned integer
    • attirbute value - several data types supported
  • Two essential attributes
    • ServiceRecordHandle
      • Uniquely identifies the service on given device
    • Service ClassIDList
      • List of class identifiers that the service belongs to starting from most relevant.
  • Other attributes
    • Defined for specific service classes
    • ServiceID is globally Unique identifier for service (UUID)
    • ProtocolDescriptorList defines the set of protocols to use for accessing the service
      • Inportant parameters for protocol use is also provided

SDPTOOL on linux

  • sdptool is application that is conducting bluetooth type service discovery
  • Searching a service
  • e.g. sdptool search OPUSH
    • search devices supporting Obex PUSH servic
  • Browsing services
    • sdptool browse
    • Browses what services are around (can be targeted to certain device
Last modified: 2013/07/01 14:41