SEKE 2012 Proceedings - Knowledge Systems Institute

contributions from the several actors. Fig. 1 presents part of the
SR model for MobileMedia [8], an SPL that will be used in this
paper as a running example. The main purpose of MobileMedia
is to manage media files in mobile devices.
Figure 1. MobileMedia i* SR model
The SR model in Fig 1 depicts two actors (“MobileMedia”
and “User”) and their dependencies. “User” depends on
“MobileMedia” to achieve the “Photo Added” goal and to
obtain “Album” resource. It also expects that “MobileMedia”
contributes to satisfy the “Integrity [Photo]” softgoal. On t he
other hand, “MobileMedia” depends on “User” to obtain
“Path”, “Photo” and “Name” resources and it expects “User” to
contribute to the “Accuracy [Path]” softgoal.
The boundary of the “MobileMedia” actor, shown in Fig. 1,
provides information on how this actor can fulfill its
dependencies and why it depends on other actors. The “Add
Photo” task is a way to satisfy the “Manage Media” goal, thus
these elements are linked by a means-end relationship. The
“MobileMedia” will fulfill the “Photo Added” dependency
through “Add Photo” task, which is d ecomposed in “Album
Selected” and “List of Photos Updated” goals and the “Store
Photo” task. “Store Photo” is decomposed in the “Quickness
[Storage]” softgoal and the “Photo Saved” goal. The “Photo
Saved” goal can be satisfied by “Save Automatically” task,
which contributes positively (“help” contribution link) to
satisfy the “Quickness [Storage]” softgoal, or by ”Save by
User” task that contributes negatively (“hurt” contribution link)
to the satisfaction of the same softgoal.
To capture variability in SR models of SPLs, an extended
version of i* has to be used. The i*-c (i* with cardinality)
allows the insertion of cardinality in task and resource elements
and also in means-end relationships [2]. This i* extension is
used by G2SPL [3] approach to derivate feature models. Our
approach is an extension of the G2SPL and, hence, it uses i*-c
models to derive not only FMs, but use case scenarios as well.
C. Scenarios for SPL
PLUSS (Product Line Use case modeling for Systems and
Software engineering) [9] is an SPL approach that combines
feature models and use case scenarios. It captures both
common and variable behavior of the SPL. In PLUSS, both use
cases and scenario steps are annotated with the features to
which they are related. During product configuration, desired
features are selected in the FM, and their corresponding
annotations, present on the use case scenarios, are used to
configure these scenarios for a specific product. Thus, only use
cases and scenario steps annotated with the selected features
will be present on the product’s use case descriptions.
III. GS2SPL
GS2SPL is an RE approach for SPL in which the feature
model and the use case scenarios of an SPL are obtained from
i*-c goal models. The GS2SPL process is divided in eight
activities, mostly are part of the Domain Engineering process
and just the last one is part of Application Engineering process.
The first four activities were inherited from G2SPL and,
therefore, they will not be explained in details in this paper.
Additional information about these activities can be found in
[3]. The rest of the process consists on the addition of new
activities or adaptations of G2SPL activities. The next subsections
present all activities of GS2SPL:
A. Creation of SR Model
This activity consists of modeling the stakeholders’ goals
using the i* framework. It is considered an optional activity if
the SR model is already available. The output of this activity,
for the running example, is depicted in Fig.1.
B. Identification of Candidate Elements to be Features
In this activity, the domain engineer identifies the elements
of the SR Model that could represent features. Features may be
extracted from tasks and resources. Therefore, all internal tasks
and resources of the actor that represents the SPL should be
highlighted, as w ell as t ask and resource dependencies
connected to this actor.
C. Reengineering the SR Model
In this activity, cardinality is added to the SR model based
on some heuristics defined in the G2SPL approach [3]. In
summary, cardinality may be added to intentional elements and
to means-end relationships in which the root element (end) has
more than one sub-element (means). The output of this activity
is an SR Model with cardinality, as the one shown in Fig. 2.
Figure 2. MobileMedia i*-c SR model with feature candidates highlighted in
grey
D. Elaboration of the Feature Model
This activity is c oncerned with the derivation of the SPL
feature model (activity output). The input artifacts are some
heuristics to elaborate the FM and the SR model with
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