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. 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 analysed by using Topological functioning model. It captures system functioning specification in the form of topological space consisting of functional features and cause-and-effect 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.