How do I obtain “model name” for a networked device (potentially using Bonjour)?

Apple's Finder.app is able to consistently determine the exact model of each physical computer that uses bonjour (as evidenced by the icons being unique for each individual device type: iMac, MacPro, MBP, etc). How do they do this and what APIs do they use?

On a side note, Bonjour provides Name, Service Type, Domain and Port for all services on the network - but I haven't been able to find information on how to find the device model itself.