The LOCATE message is used by service clients to discover the existence and state of services on the network. Sent as a UDP broadcast it requests information about a specific service.
Upon receipt of a LOCATE, the relevant service is expected to respond immediately by broadcasting an ANNOUNCE message to enable the client to understand the current state of the service.
LOCATE [service name]
|service name||A name for the service, well known within the system domain|
A typical LOCATE message would look like this.
Use of the LOCATE message is optional by the client if the intervals between ANNOUNCE broadcasts by the service are sufficiently small. In many situations though, this delay is unacceptable and the client will initiate the ANNOUNCE broadcast by sending a LOCATE message.
Having both LOCATE and ANNOUNCE messages also has the side benefit of allowing the protocol to have a comedy name.