Introduction

Use case analysis of a system (or its part) is concerned with

• specifying the outcome of the communication between the system (or subsystem) and external actors (human or automated systems) who are its users, developers and domain experts;
• capturing and analysing system functionalities (requirements);
• validating its architecture;
• verifying its services;
• testing its parts and its integrity;
• the variety of sequences of actions performed (scenarios) by it in response to its external user requests;
• what it and its parts do in response to requests by its users, developers and domain experts (but not how the response is realised by its implementing collaboration).