Writing Better Real-Time System Requirements with Use Cases and Services

An average person in North America comes in regular contact with an amazing number of real-time systems on a regular basis. For example, an automobile today can have upward of 40 plus real time systems on board. A residential house has real-time systems in many household electronics.

Real-time systems today deliver many customer-facing functionalities. There is a need to express requirements in a manner relevant the customers, for purposes of validation and verification. The proliferation of real-time systems on a single device also creates opportunities for reuse of functionality that rarely existed before.

Use Case technique approaches requirements from a scenario perspective. Scenario provides context and external view points that are better suited to address the validation, verification and reuse challenges. In this paper, we present:

• A few examples of extending use cases for real-time systems to capture system functional requirements.
• A set of guidelines for defining the notion of service
• Reuse of services across Use Cases