Early Availability Requirements Modeling Using Use Case Maps

Abstract

The design and implementation of distributed real-time systems is often dominated by non-functional considerations like timing, distribution and fault tolerance. As a result, it is increasingly recognized that non-functional requirements should be considered at the earliest stages of system development life cycle. The ability to model nonfunctional properties (such as timing constraints, availability, performance and security) at the system requirement level not only facilitates the task of moving towards real-time design, but ultimately supports the early detection of errors through automated validation and verification. This paper introduces a novel approach to describe availability features in Use Case Maps (UCM) specifications. The proposed approach relies on a mapping of availability architectural tactics to UCM components. We illustrate the applicability of our approach using the ISSU (In Service Software Upgrade) feature on IP routers.