20. A semantic server storing a local semantic graph comprising concept instances and relations between the concept instances, the semantic server comprising: an input/output module to receive data including semantically descriptive annotations from distributed sources; a processor programmed to process data based on the semantically descriptive annotations of the data to form the local semantic graph that associates the concept instances with each other using the relations, to create at least one subscription of interest in response to a request from at least one client and to send at least one alert to the at least one client based on updates to the local semantic graph matching the at least one subscription of the at least one client; and memory for storing the local semantic graph, the local semantic graph comprising part of a network semantic graph distributed among a plurality of semantic servers.
32. The semantic server of claim 20 , wherein the at least one subscription includes a plurality of temporal events for the at least one client and wherein the processor is further programmed to send alerts to the at least one client when at least one of the plurality of temporal events occur.