Information Technology Reference
In-Depth Information
Scenarios are considered to be text-based descriptions of systems, expressed in
natural language, similar to stories or narrative examples described in Agile meth-
ods [ 2] . Scenarios contain realistic detail about systems, their environment, users,
interactions and activities.
Storyboards and informal sketches are drawings of system designs and the system
environment showing realistic layout of objects, artefacts and their context.
Informal models and notations are models of the system and its environment
expressed in a semi-formal diagram language, such as data flow diagrams, object
relationships or activity sequence diagrams.
Formal models and system specifications are expressed in a rigorous mathemati-
cally based language, e.g. Z, SCR, KAOS [ 38] .
Prototypes are software artefacts which present partial implementations of the
design system.
The cognitive affordances of these representations are illustrated in Table 2.
Clark's communication modalities have been revised with criteria drawn from
the cognitive dimensions framework [ 9] which is more closely oriented toward
representations:
Interaction: how easy it is to point to and manipulate representations during team
meetings.
Comprehensibility: how easily understood a representation is by ordinary users
without specific training.
Testability: how easy it is to challenge and evaluate assumptions and facts
expressed in a representation.
Scenarios are reviewable and revisable since text can be scanned and edited,
although the ease of revision is enhanced by word processors. Scenarios are eas-
ily comprehended, but interaction is limited to indicating particular sections of a
narrative. Scenarios, since they express specific instances and examples, are not
testable by themselves, although a collection of scenarios can form test cases for
specifications [ 18] . Storyboards and sketches are easy to review but less easy to
revise even with software drawing tools, and interaction is limited to pointing to
Ta b l e 2 Assessment of RE representations to illustrate affordances for collaboration
Reviewability Revisability
Interaction Comprehensibility Testability
√√
√√
√√√
Scenarios
-
x
√√√
√√
√√√
Storyboards
and sketches
x
√√
Informal mod-
els/notations
√√
Formal models
-
-
-
xx
√√
√√
√√
Prototypes
-
 
 
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