1. A computer-implemented method for monitoring transactions in a computer system, comprising: monitoring events reported by components of the computer system responsively to a flow of the transactions through the system; applying a state machine model to the monitored events so as to identify transaction-level events, and applying a rule-based model to the monitored events so as to identify business-level events; performing at least one action selected from a group of actions consisting of: modifying, responsively to at least one of the business-level events identified by the rule-based model, a first criterion applied by the state machine model in identifying one or more of the transaction-level events; and modifying, responsively to at least one of the transaction-level events identified by the state machine model, a second criterion applied by the rule-based model in identifying one or more of the business-level events; and assessing a status of the flow of the transactions responsively to the transaction-level events and the business-level events.