Just as with real-time indexes, another technical challenge of real-time data processing is achieving acceptable messaging performance. What Apama’s diagram (Figure 4) refers to as "alerts" would typically be voice, e-mail, or short messaging services messages activated by database triggers. Triggers start procedures whenever a predefined condition occurs. For example, a trigger might fire when a mobile device crosses a state boundary or exceeds a speed limit. Unfortunately, triggers are slow performers, especially when a million or more are fired simultaneously.

Firms, such as iSpheres (www. ispheres.com), that build software for large emergency response systems have solutions tailor-made for routing many simultaneous messages throughout a group of participants. Their middleware may supply the messaging or triggering component of an LBS back-office system.

Back-office players. The probable champions of the LBS segment of realtime data processing market are the electronics providers (Nokia, Motorola, Ericsson, Samsung, Qualcomm, and so forth) and the network telecommunications operators (such as Airtel, blu, orange, kpn, sfr, m1, pacific access, Proximus, TIM, Voice stream, Vizzavi, Sprint, AT&T, MCI, and DoCoMo). Other players are the technology and infrastructure providers (IBM, Nortel Networks, OpenWave, Oracle, Signalsoft, and the like) and the content and service providers (including Borg, ADAC, NavTech, and Wireless Car). Also in the game are companies like Webraska (www.webraska.com) that are pushing to become turnkey LBS integrators, partnering with all of the aforementioned players. How these groups relate to each other is different depending on the continent (North America, Asia, or Europe) and is still playing out.

However and whenever these big players corner the LBS market, though, we spatial professionals can count on seeing more and more realtime data appearing as valid layers in our formerly all-static spatial applications. And as private citizens, whether our real-time history is private or the domain of a cell phone provider, there may come a day when we all would willingly offer a week’s worth of our event datasets to a Center for Disease Control expert to answer the question, "Was I exposed to a biological attack?" Depending on the answer, the next real-time challenge could be avoiding traffic on the way to the emergency room. Even if prompted by the terrible events of September 11th, may the appearance of real-time data in your future spatial projects result in more accuracy and timeliness of analysis. Life in the US may never be the same, but intelligent use of realtime spatial data might someday improve it.