Deriving Use Cases for Distributed Systems from Knowledge Requirements

Xiao Jun Chen
School of Computer Science
University of Windsor Windsor ON Canada
xjchen@cs.uwindsor.ca

Luigi Logrippo
School of Information Technology and Engineering
University of Ottawa Ottawa, ON Canada
luigi@site.uottawa.ca

Abstract

Knowledge requirements for distributed systems express desired states
of affairs concerning initial and final knowledge of the components
of a system. It is shown how use cases (i.e. sets of scenarios) can
be obtained from knowledge requirements. The technique involves the
use of event structures that specify use cases capable of achieving
the requirements, and logical postconditions for events. The technique
allows design refinement, both in the form of architectural refinement
and in the form of event refinement. The correctness of refinements can
be checked by checking logical implications. As an example, use cases
and scenarios for a simple mobile telephony protocol, based on GPRS (the
data extension of GSM) are derived, on the basis of the corresponding
knowledge requirements. Scenarios are given in the form of Message
Sequence Charts.

Keywords:
  Use cases, scenarios, logic specifications, knowledge requirements,
  event structures, distributed system design, protocol design.