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https://ceur-ws.org/Vol-766/paper21.pdf
CEUR Proceedings of the 5th International i* Workshop (iStar 2011)
Issues and Challenges in Coupling Tropos with
User-Centred Design
L. Sabatucci, C. Leonardi, A. Susi, and M. Zancanaro
Fondazione Bruno Kessler - IRST CIT
sabatucci,cleonardi,susi,zancana@fbk.eu
Abstract. Goal-oriented requirements engineering aims at eliciting, elab-
orating, structuring, specifying, analyzing and documenting functional
and non-functional requirements. This activity must include the involve-
ment of final users of the system across the whole process to reduce the
risk of misunderstanding the domain, missing important details and to in-
crease the final value of the product. User-Centred Design is an approach
that focuses on the continuous communication between requirements en-
gineers and stakeholders, thus distributing responsibilities of the decision
process about the requirements.
In this paper we explore the issues and challenges of coupling User-
Centred Design and Goal-Oriented methods as we experienced in a real
project aiming at developing smart environment for nursing home to
support medical and assistance staff.
1 Introduction
When facing the problem of designing technologies, two roads diverge in the
wood: Requirements Engineering (RE) and User-Centred Design (UCD). Indeed,
both approaches ground their processes in information about the people that are
directly or indirectly involved by the technology that has to be developed. Yet,
they not only have different set of techniques and incompatible vocabularies
but also they are based on two diverging epistemological foundations. UCD
practitioners shun from any formal method at risk of compromising the actual
use of the knowledge gained in the field. On the other side, RE practitioners
often loose contacts with real people because formalizations cannot easily be
shared with them: user analysis thus becomes a single-player game rather than
a meaningful dialogue with stakeholders.
The need of reconciliation was raised in our experience with a large research
project aimed at developing a smart environment in nursing home as support
to medical and assistance staff. Since the beginning, we adopted the Tropos
methodology and encountered a well-known problem in requirement elicitation:
the complexity of the domain makes it difficult not only to understand users’
needs but also to discuss with them our understanding of the domain.
In parallel, we adopted a UCD approach, mainly based on contextual inter-
views: our aim was to elicit true needs by observing daily practices and not only
prescribed regulations. Activity scenarios were sketched to test with users our
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CEUR Proceedings of the 5th International i* Workshop (iStar 2011)
understanding of their working practices. The narrative form of scenarios and
the use of fictional personas made easier the confrontation between the analysts
and the stakeholders. Later on, those scenarios were augmented with our vision
of the technology. Again, the narrative form made the communication easier
for them to understand and discuss in a tangible way. The issue with this ap-
proach, again well known in literature, was the lack of formality in collecting
and analyzing the results.
The contribution of this paper is the analysis of foundations for the inte-
gration of the two approaches without compromising their very nature: in the
differences there lies the power of the integration and its risks. The practical
experience of mediating these two perspectives represents the basis for a discus-
sion of generic issues and challenges that arise for the integration of User-Centred
Design and Goal-Oriented methods.
The paper is structured as follows: Section 2 introduces the practical experi-
ence that motivates the research objective; Section 3 is a discussion of challenges
arising from generalizing the problem; finally in Section 4 conclusions and future
works are reported.
2 Objective
Our general research objective is to maximize the connection between the very
early stages of the domain analysis and requirements elicitation and the phase of
their representation into semi-formal artifacts, such as goal-oriented techniques,
to reason about them.
An initial approach to this coupling has been exploited in a real project and
described in the next section. On the bases of the experience, our aim here is that
of describing how, under what conditions and at what extent this experience can
be generalized.
2.1 The Methodologies
The Tropos methodology [5] relies on a set of concepts, such as actors, goals,
plans, resources, and dependencies to formally represent the knowledge about
a domain and the system requirements. An actor represents an entity that has
strategic goals and intentionality within the system or the organizational setting.
Goals represent states of affairs an actor wants to achieve. A Plan is a means
to realize a goal. Actors may depend on other actors to attain some goals or
resources or for having plans executed.
User Centered Design. UCD is a design philosophy that exploits a num-
ber of different techniques within an iterative design process. Tenets of UCD are:
early focus on users, tasks and environment, the active involvement of users in
the design process, allocation of functions between user and system, the incorpo-
ration of user-derived feedbacks into system design, iterative design whereby a
prototype is designed, tested and modified. UCD exploits a series of well-defined
methods and techniques coming from social sciences and psychology for analysis,
design, and evaluation technologies.
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CEUR Proceedings of the 5th International i* Workshop (iStar 2011)
Fig. 1. Overview of the requirement elicitation process
2.2 The Experience: an Ambient Assisted Living System
The whole experience was articulated in seven phases all of them characterized
by the use of both Tropos and UCD (see Figure 1).
Phase 1 - Field data collection. The process started with the investigation
of the domain in order to understand the organizational setting in four nursing
homes and to identify the needs of the stakeholders involved. In order to get rich
insights about the context, we used contextual inquiry that demonstrated the
capacity to satisfy the needs for a deep but at the same time rapid understanding
of complex domain. Contextual inquiry consists in observing and interviewing
people in their context, preferably when performing their tasks.
Phase 2 - Data Interpretation. The data interpretation is the step in which
data coming from the domain is shared across the team and becomes knowledge.
In our process, data interpretation is concurrently carried out: i) following con-
textual design approach dimension (flow model, sequence model, cultural model,
artifact model, physical model) and ii) exploiting the early identification phase
of Tropos.
Phase 3 - Problem analysis. The analysis of critical aspects was developed to
highlight main problems that professionals of nursing homes experience in their
job. The aim is to highlight every possible breakdown or problem that may occur
in the organization that hinders the achievement of goals. A criticality relates
an exceptional event to front with Tropos goals and tasks that are identified to
receive a negative contribution. It also encapsulates the context in which the
problem may occur.
Phase 4 - Personas and activity scenarios design. Introducing personas in
scenarios-based approach provides an anchor against self- referentiality in design
and make stories more concrete. We authored a set of activity scenarios — user
stories about problems and criticalities identified through user studies.
Phase 5 - Envisioning, from data to design. The phase of envisioning ex-
ploited participative workshops in order to move from personas and activity sce-
narios identified in Phase 4 in order to envision how to introduce the technology
in the analyzed domain. As a consequence of the envisioning focus group, and
the introduction of the system into the goal-model, the Tropos process moved
from the early requirement phase to the late requirement phase.
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CEUR Proceedings of the 5th International i* Workshop (iStar 2011)
Phase 6 - From design ideas to Tropos modeling. Tropos diagrams and scenar-
ios were jointly used to refine the ideas emerged during the creative workshops.
On one hand, technological scenarios were designed to make design ideas con-
crete and to trigger reflection about possible services. On the other hand, Tropos
diagrams were developed to more systematically analyze how the introduction
of a system impacts on the domain actors.
Phase 7 - Evaluation of technological scenarios. Here visual scenarios were
derived from the Tropos models and used for the validation phase (focus groups
with stakeholders), where multiple views on the domain are required to drive
the negotiation and refinement of requirements with stakeholders and project
partners. If envisioning scenarios provided a concrete instance of a particular
design solution, that is very helpful to discuss with stakeholders, on the other
hand, Tropos diagrams aided designers in reconsidering design solutions and
elaborating alternatives thanks to the possibility to trace back design solution
to initial abstract requirements. The output of this phase was the agreement on
early requirements and the refinement of Tropos late requirement diagrams.
3 Contribution: Integration Issues and Challenges
Crossing boundaries between two research approaches requires — borrowing a
distinction from social sciences — either an assimilation or an integration pro-
cess. In the case of assimilation, one approach must be modified to be assimilated
into the other approach: while the risk is to loose the strength of the approach
itself, the advantage is to work in a situation of methodological purity [6].
In the case of integration, as well as in our experience, practitioners should
accept to work in a situation of methodological pluralism: the goal is not to
transform a specific approach to make it fit into another one, but rather to
bridge the gap between different research traditions and take advantages of their
mutual strengths. Usually, the integration is more complex because practitioners
work into different methodological traditions that have to be first understood
to be integrated [7]. Integration, therefore, requires creating preconditions for a
beneficial dialogue.
In the ACube project we recognized the irreducible cultural difference be-
tween the two approaches and therefore decided to work in a dialogic perspective,
that is grounded on communication and iterative confrontation [4]. The follow-
ing considerations come from generalizing the practical experience in coupling
Tropos and UCD.
3.1 Epistemological challenge
The first issue is to consider epistemological foundations and validity criteria of
both the approaches to manage the differences without weakening and distorting
the two research paradigms. Whereas several methods employed in UCD derive
from a constructivist perspective, many requirement engineer approaches are
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CEUR Proceedings of the 5th International i* Workshop (iStar 2011)
grounded, instead, on a constructivist perspective — even if the debate on the
positivist nature of many RE methods has recently been criticized [3].
Constructivism declares there is no single valid methodology and researchers
play an active role in defining the reality. User-centered design is grounded on
this research tradition: hence the scarce formality of methods, the subjective
insights developed by practitioners, and the ambiguities in the analysis are, if
correctly managed, not only accepted but actively perused [1].
Concerning the design activity, the positivist position suggests a rigid struc-
ture for the modeling activity and the reasoning process: while for construc-
tivism, scientific knowledge is built by scientists, for positivism the knowledge is
’discovered’ by the use of actual sense experience. The criticism on the positivist
nature of goal-models relies on the semi-formality of such languages: there is no
one ’right’ goal model for describing a domain [3].
The integration challenge must consider these epistemological differences and
be grounded on setting the pre-conditions to mediate these philosophical posi-
tions and generate a profitable dialogue between the two methods.
3.2 Linguistic Challenge
Near the methodological boundary, a linguistic boundary exists. The concurrent
usage of both approaches requires that a common language exists in order to
make a dialogue possible. For instance, several concepts exist in both Tropos and
UCD that suggest an integration is possible and profitable; examples of these
are the pairs of goal/need, actor/persona, task/activity; yet these terms have
slight different meanings in the two methodologies that hinder the integration
process.
The identification of a common language for coupling the methodologies must
pass through a reconciliation of terms. Two alternatives are possible: (i) to create
a unified meta-model of the integrated process, or (ii) to tie up terms with
similar meanings while keeping them separate. The first way is fascinating but
it presents some notable risks, such as, for instance, the loosing of the flexibility
and expressivity of tools like personas and scenarios that often requires to be
unbounded within precise frames. The second way is preferable but it requires
an additional effort for creating a framework in which data of different nature
can easily collaborate.
3.3 Lesson Learned
By recapping the design experience described in Section 2.2, we can recognize
three main mechanisms that shaped the relationships and set the dialogue for
an efficient cooperation between the two teams:
– Strengths/limits analysis: it relies on the identification of strengths and limits
of both the methods while achieving a given design objective. This allows
to define integration points between UCD and RE methods and take full
advantages of their reciprocal strengths.
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CEUR Proceedings of the 5th International i* Workshop (iStar 2011)
– Making the divides explicit: it consists in identifying barriers that may hinder
the dialogue between the two methods. The anticipatory exploration of the
barriers that can prevent a synergy between the two approaches was pursued.
– Mutual learning: social-based techniques may enable continuous information
exchange and communication to overcame the linguistic barriers, to facilitate
the negotiation of meanings and to share common modeling tools during the
analysis activities.
4 Conclusions and Future Works
In this paper we addressed some of the challenges posed by a joint use of the
human-centered and goal-oriented requirement engineering approaches, start-
ing from the experience done within in a real ambient assisted living project.
We discussed how a dialogic relationship between the disciplines may provide
guidance for researchers from requirement engineering and human centered de-
sign field that cooperate within the same design process. In this perspective,
the orchestration of different contributions, the establishment of communication
practices and the engagement within a mutual learning process are presented as
crucial steps to take full advantage of different research traditions. We finally
made some hypothesis on how to generalize such an approach and discussed
some issues related to this generalization.
In the future, we would like to explore in more details some issues emerged
during the experience in the project and the subsequent discussions. In particu-
lar: from a methodological point of view we would like to explore the interaction
of the two different approaches also exploiting principles form meta method-
ologies [2]; the other side we aim at refining the dialogue issues in linguistic
interactions, also exploiting cognitive linguistics and ontology based approaches.
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