Linking Goal-Oriented Requirements and Model-Driven Development - Intentional Perspectives on Information Systems Engineering - page 253

2.1 The i ∗ Goal-Oriented Requirements Framework Overview
Appropriate requirement capturing and elicitation is one of the most important
activities in software development, thus the relevance of requirements engineer-
ing (RE) to obtain a sound software engineering process. RE clarifies what users
want, how they are going to interact with the system, and how the system impacts
the business. If these ideas are projected onto the model-driven philosophy, it
can be stated that requirement modeling is fundamental in obtaining a sound
Model-Driven Engineering (MDE) [ 18] process for software development. The
paper presented in [ 38] clearly shows the relevance of integrating different mod-
eling approaches to obtain a sound modeling process. This is precisely what we
want to achieve with the linking of goal-oriented modeling and MDD-oriented
modeling.
In the RE domain, the goal-oriented perspective has provided interesting results
at both the industrial [20] and research levels [ 43] . The Goal-Oriented Requirement
Engineering is concerned with the use of goals for eliciting, elaborating, structur-
ing, specifying, analyzing, negotiating, documenting, and modifying requirements
[ 19] . In general terms, it focuses on obtaining the 'what' of the intended systems
through the analysis of organizational scenarios. The work presented in [ 39] shows
the relevance of using scenarios for goal modeling, what provides the background
for the RE modeling approach considered in this paper.
Among existing GORE approaches, the i ∗ framework [ 45] is currently one of
the most widespread modeling and reasoning frameworks [ 20, 29, 43] and is also
well documented [ 25] . It emphasizes the analysis of strategic relationships among
organizational actors capturing the intentional requirements. The term actor is used
to generically refer to any unit for which intentional dependencies can be ascribed.
Actors are intentional in the sense that they do not simply carry out activities and
produce entities, but they also have desires and needs.
The i ∗ framework offers two types of models: the Strategic Dependency (SD)
model and the Strategic Rationale (SR) model. The SD model is focused on external
relationships among actors. It includes a set of nodes and connecting links, where
nodes represent actors ( depender and dependee ) and each link indicates a depen-
dency ( dependum ) between two actors. There are four possible dependum elements:
goal , resource , task , and softgoal .A goal in the i ∗ context is a condition or state of
concerns that the actor would like to obtain. A resource is a physical or informa-
tional entity that must be available for an actor. A task specifies a particular way of
doing something, which can be decomposed in small sub-tasks. Finally, a softgoal
is associated to non-functional requirements.
The SR model is a detailed view of the SD that shows the internal actor rela-
tionships. In addition to the dependencies that are present in the SD model, the SR
model incorporates three new types of relationships: (i) task-decomposition links,
which describe what should be done to perform a certain task; (ii) means-end links,
which suggest that a task is a means to achieve a goal; (iii) contribution links, which
suggest how a model element can contribute to satisfying a softgoal.