The Bluetooth protocol is used to discover the service information of each device. They are used to set up the connections between the Bluetooth devices and to transmit all the information relevant for data transmission.
With the Service Discovery Protocol (SDP), the SDP client starts a request with an SDP request to the SDP server, which sends it an SDP response. The Service Discovery Protocol (SDP) is an IEEE specification of802.15.1. In addition to the standard version, there is also a simpler version, the Simple Service Discovery Protocol( SSDP).