According to the disclosed approaches, a first processor receives location messages from second processors. Each location message specifies published geographical coordinates that indicate a geographical location, and the published geographical coordinates are a version of actual geographical coordinates truncated from a first level of precision to a second level of precision. The first processor accesses subscriptions to location topics in response to the location messages. Each location topic specifies in the second level of precision, subscribed-to geographical coordinates of a location. The first processor determines whether or not the published geographical coordinates match any of the subscribed-to geographical coordinates. Non-matching location messages are discarded, and matching location messages are transmitted to one or more third processors identified by the subscriptions.