Not sure if this is an openhab thing or an smarthome thing - so please let me know if I should post elsewhere.
Is there any way to 'discover' the running server? Let's say I have another server that needs to discover all running servers on the network. Does openhab/smarthome provide a way to discover the instances (mdns or upnp or ???)?
ESH provides the basic mDNS infrastructure to participate in service discovery and service broadcasting (the package your link is pointing to). It does not bring its own functionality to discover other ESH instances or announce itself on the network.