Collaborative Requirements Engineering: Bridging the Gulfs Between Worlds - Intentional Perspectives on Information Systems Engineering - page 355

Fig. 2 Combination of
representations for common
ground in the perspective of
RE activities. Two areas of
common ground are
illustrated, one shared by
requirements engineers (RE1,
RE2) and user stakeholders
(S1, S2), and the other only
shared among requirements
engineers

Generate
Solutions

Generate
Solutions

scenarios
storyboards
prototypes
models

Think & Think & Think &

Critique

Think &
Critique

Critique Critique

Elicit &
Summarise

Elicit &
Summarise

Common
Ground

Common
Ground

Common
Ground

RE1 RE1 RE1 RE1

RE2 RE2 RE2 RE2

Common
Ground
S1

Common
Ground
S1 S2
RE2

Common
Ground
S1 S2
RE2

Validate
Communicate

Analyse &
Reflect

Analyse &
Reflect

Validate
Communicate

S1 S2

RE2

S2

RE1

RE1 RE1 RE1 RE2

Check &
Verify Negotiate

& Agree

Negotiate
& Agree

Converse Converse

& Discuss

& Discuss & Discuss

& Discuss

model
formal
languages

Informal models enable abstract viewpoints to be debated; but models may hide
ambiguities and, worse still, assertions may go unchallenged. Models, even informal
use cases and data flow diagrams, belong to the realm of the requirements engineer,
rather than being part of users' normal discourse. Hence there is a tendency for
disjunction to appear between specific and abstract common ground, with require-
ments engineers focusing on abstractions and users tending to favour the specific.
The solution to this dilemma is to juxtapose concrete and abstract representations,
for example using scenarios to challenge models and vice versa. This intuition has
emerged in some RE methods such as ScenIC [ 18] where a range of scenarios
provide challenges to input process specified in models and then the acceptabil-
ity of output from system models is evaluated in the light of scenarios of use. This
combination of representations helps to bridge the concrete and abstract division in
common ground, as summarised in Fig. 2.

4.3 Negotiate and Agree

Negotiating, prioritising and achieving mutually agreed requirements all focus on
the process of establishing common ground between stakeholders. Representations
have a special role to play in this activity since common ground in conversation is
limited by working memory to about five topics or ideas [1, 32] . Working memory is
the human equivalent of cache memory; unfortunately its contents are limited, and
become lost as they are overwritten by new input. This means we can only process a
limited quantity of information at once. However, decisions and negotiations require
consideration of many facts and options. Representations overcome the limitations