A processor (2) in a transaction processing system (1) has an event engine and a scenario engine. The event engine stores a framework (20) for each entity or type of service. The framework (20) has a parent class (21) and subsidiary classes (22-27). In real time the event engine instantiates an event object from a relevant class (22-27), giving it an effective time on a timeline of the parent class (21). The event objects many subsequently be handled as autonomous units for generation of reports or batch processing. The event engine moves the event objects between states of a finite state machine. A scenario engine also manipulates objects according to a finite state machine with future dates as the effective times. There is a state transition from the scenario environment to the event engine (live) environment.