RSI - A Structured Approach Use Cases and HCI Design

The RSI Approach To HCI Design / Use Case Analysis Page 4 of 42
W5a - RSI LONG PAPER [42 PAGES].doc( Rev: 5) - 03/09/00
Abstract
Use case analysis is the de-facto standard technique for requirements capture in the OO
development world. When engineers first undertake use case analysis, a number of issues are
raised for which easy answers can't be found in the text books. These include:
• How does user-interface design fit into the use case analysis process?
• Should user interface dynamics be included?
• What is the appropriate level of granularity (size) and abstraction (detail) for use
cases?
• If large grained use cases are used, should they be decomposed into 'lower level' use
cases?
• If so, at what point should this decomposition stop, and how should these sub-use cases
be used?
• What are the 'relationships' between these use cases?
• How should this decomposition be approached from a process perspective?
• How are used cases related to object models? Should the 'things' referred to in use case
descriptions be cross-referenced against object models?
This paper describes the «requirements»/«service»/«interface» (RSI) approach to use case
analysis. This approach provides a framework for analysing and understanding potential use
case deliverables and their inter-relationships, with a view to answering the questions such as
those detailed above.
In particular it puts user-interface design centre stage within the use case analysis process,
provides a set of standard classifications for use case granularity, provides placeholders for
other interface deliverables, and gives clear traceability from high level requirements to
system interfaces.