I have become a user of Brightkite, a service that provides situational awareness in the geographical context. Once its relationship to user location information sources such as Fire Eagle improve, it may become a very nice tool, especially in mobile use cases where location reporting may be partly automated.

But even if they add technical value in the growing world of geographically aware applications, theses services are actually not innovative at the functional level. For example, in the ham radio universe, APRS is already a great system for real time tactical digital communications of information of immediate value in the local area – which includes among other things the position of the participating stations. And there is also TCAS, which interrogates surrounding aircrafts about their positions, and AIS which broadcasts ship positions and enables the entertaining Vessel Traffic Services such as the one provided by MarineTraffic. All these radio based systems broadcast in the clear and are not satisfying the privacy requirements of a personal eventing service. But that problem has also been solved by the Blue Force Tracker which even though it is still a work in progress has already changed how a chaotic battlefield is perceived by its participants.

“Where am I, and where are my friends ?” is not only the soldier’s critical information – it is also an important component of our social lives, witness the thriving landscape of geosocial networking. Geographic location is a fundamental enabler : we are physically embodied and the perimeter of location based services actually encompasses anything concerning our physical presence. So we can’t let physical location services escape our control. Fire Eagle may be practical for now, but we need to make geographical information part of the basic infrastructure under our control and available on a standardized, open and decentralized basis. The good news is that much thoughts have already been invested into that problem.

Physical location is part of our presence, and as you may have guessed by now, this means XMPP comes to the rescue ! We have XEP-0080 – User Location, an XMPP extension which is currently a XMPP Foundation Draft Standard (implementations are encouraged and the protocol is appropriate for deployment in production systems, but some changes to the protocol are possible before it becomes a Final Standard – as good as a draft standard RFC and therefore good enough for early adopter use). It is meant to be┬ácommunicated and transported by means of Publish-Subscribe or the subset thereof specified in Personal Eventing via Pubsub. It may also be provided as an extension of plain vanilla <presence/> but that is quite a crude way to do it compared to the Publish-Subscribe goodness.

The rest of the work is left to the XMPP client. Of course, the client can show them on a map, just as Brightkite currently does. But I can also easily imagine an instant messaging contact list on my PDA where one of the contact groups is “contacts near me”. I would love to have Psi do that…