1. A method for monitoring one or more transaction instances in a real-time network, comprising the steps of: obtaining one or more system log files, wherein one or more footprints left by one or more transaction instances are recorded in the one or more system log files; obtaining a transaction model, wherein the transaction model comprises one or more transaction steps and a footprint pattern corresponding with each transaction step; and using the one or more system log files and the transaction model to monitor the one or more transaction instances in a real-time network at least one of an individual level and one or more aggregate levels.