Event-driven software systems continuously wait for occurrence of some external or internal events. When such event is received and recognized, the system reacts by performing corresponding computations which may include generation of events that trigger computation in other components. After the event handling operation is complete the system returns to the waiting state for the next event occurrence. The response to the received event depends on the current state of the system and underlying objects and can include a change of state leading to a state transition. The state changes and transitions within a system can be formally analyzed by using functional characteristics of Topological functioning model (TFM). TFM captures system functioning specification in the form of topological space consisting of functional features and cause-and-effect (i.e. topological) relations among them and is represented in a form of directed graph. The functional features together with topological relationships contain the necessary information to create State diagram which reflects the state changes within system.