SDP (Service Discovery Protocol)

This protocol is needed in the Bluetooth environment; it provides the basis of all the usage models. is a simple protocol with minimal requirements on the underlying transport. It can function over a reliable packet transport (or even unreliable, if the client implements timeouts and repeats requests as necessary). SDP uses a request/response model where each transaction consists of one request protocol data unit (PDU) and one response PDU. However, the requests may potentially be pipelined and responses may potentially be returned out of order.

SDP uses a request/response model where each transaction consists of one request protocol data unit (PDU) and one response PDU. In the case where SDP is used with the Bluetooth L2CAP transport protocol, only one SDP request PDU per connection to a given SDP server may be outstanding at a given instant. In other words, a client must receive a response to each request before issuing another request on the same L2CAP connection. Limiting SDP to sending one unacknowledged request PDU provides a simple form of flow control.