VisualQTH is now essentially complete in its critical features.
A UDP listener is now implemented in order to respond to N1MM 'external broadcast' messages. As N1MM sends XML in the datagram, the actual code to handle the message is only about 4 lines long (Cocoa giveth very nicely in this case). Setting up the UDP socket isn't something Cocoa helps with, but I've done this a few times before, and some old code from my XPlaneCentre app served again very well :-)
So now, you can use N1MM on a machine on the LAN, and with 3 extra lines of code in the .ini file, you can have it send log messages to a machine running VisualQTH. VisualQTH maintains its own database of contacts and stations, thanks to the excellent Core Data, and so you can stop/restart the application and continue where you left off.
I'm now moving into the realm of "nice to have" features - at least for the intended purpose of the club field day. These will include synthesized 'QSL cards' for stations that don't have an image filed with QRZ. I'm thinking of putting up a flag of the country, with some overlaid text showing available address info.
I'd also like to implement some 'stats' in the bottom pane of the display, showing various totals and breakdowns (e.g. a pie chart for country). It would be nice to have a display of more information for the last contact made, if this information is available - perhaps in a pop-up info box in the map, or in the information display. Perhaps enough stations have a bio or website that could be displayed somehow.
After this, it's just a matter of testing it with the club machines to make sure everything works as planned.