1. A system network comprising: one or more computing devices with at least a processing unit and memory; a processing system implemented by the processing unit and memory of at least one of the computing devices, the processing system including a plurality of applications, each application being associated with at least one other of the applications in an application pair, each application pair being configured to transfer business events there between, each application pair having a corresponding set of rules for generating correlation information based on the business events being transferred, different application pairs being capable of having different sets of rules for generating correlation information based on the business events being transferred, each application being configured to generate and send event messages including the correlation information when a business event occurs, the correlation information being generated and sent based on the set of rules for each application pair; and a tracking system implemented by the processing unit and memory of one of the computing devices, the tracking system including an event collector configured to receive the messages from the applications, the tracking system also including an event aggregation module having a relations data store, the event aggregation module being configured to generate unique tracking identifiers for each business event, the relations data store containing a record of messages for a plurality of business events that are associated with each unique tracking number for each business event, the event aggregation module being configured to correlate related messages based at least in part on the correlation information contained in the messages, and to update the relations data store to associate the related messages pertaining to the business event with the respective unique tracking identifier, wherein the tracking system does not correlate related messages using the unique tracking identifiers.