There is provided a system having a plurality of information processing apparatuses, each of which includes a storage device where at least one piece of pattern data indicating an occurrence pattern of events to be detected in the information processing apparatus is stored, a generation section that specifies a collection of events to be detected in the occurrence pattern based on the pattern data read from the storage device and generates necessary event data indicating the specified collection of events, a selection section that selects an event included in the necessary event data from events which have occurred in the information processing apparatus and events transferred from another information processing apparatus, and a detection section that detects if the selected event matches with the occurrence pattern indicated by the pattern data, and outputs a detection result.