Discovery Service

The LRSN discovery mechanism provides a way of dynamically discovering devices that are capable of responding to LRSN commands.

The discovery protocol is based on the DNS Service Discovery (DNS-SD) protocol and Multicast DNS (mDNS) protocol. This combination is commonly referred to as Bonjour.

Definitions

• Server - A device that is capable of accepting TCP/IP connections from other devices and speaks the LRSN protocol.
• Client - A device that that has established a TCP/IP connection to a server.

Service Advertisement

A server should advertise a service type of _lrsn._tcp on the local domain. This enables easy discovery of all LRSN enabled devices. Server names are restricted to names that do not conflict with existing servers, and are compliant with the DNS-SD specification.

Server TXT records are not used by the LRSN discovery protocol, and may be used by the application. A server should advertise the specific LRSN application domains that it can be used for. The following application domains are available:

• _lrsn-netpage._tcp for NetPage capable LRSN servers.
• _lrsn-rwe._tcp for RemoteWaitEntry capable LRSN servers.
• _lrsn-tableman._tcp for TableMan capable LRSN servers.

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A server should only advertise services which it is configured to make available to its clients.

Service Discovery

Finding LRSN capable devices is as simple as using an available Bonjour stack to find the servers that are advertising the desired service type.