Information Technology Reference
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findings (industry-oriented seminars and tutorials, etc.). Due to the nature of this
book, we will focus on the first topic.
This chapter provides an overview of some of the most relevant scientific chal-
lenges that shall be overcome in order to attain (at least partially) this knowledge
transfer goal. Because of length limitations, we will concentrate on challenges
related to the framework's modelling language more than to analysis techniques
defined around. For each challenge, after reviewing its context, the problem to be
solved and the state of the art, research directions are proposed and justified. As a
result, we expect to stimulate research in the community along these directions and
thus to effectively help bridging the gap among researchers and practitioners in the
use of the i framework.
2 Challenge 1: Agreeing on the i Metamodel
Context. Since it was first released in 1995, the i framework has been adapted to
the needs of specific research groups that wanted to represent concepts specific of
their application domain, like security [28] , temporal precedence relationships [ 23]
or architectural concepts [ 31] . Furthermore, even the original framework had several
variations (GRL for standardization purposes [ 67] , the Tropos methodology on top
of i [ 7] ) and experienced a natural evolution on time that has led to a slightly
modified version available in the i wiki [ 36] . As a result, we may conclude that
there is a plethora of variations available in the community, used by several authors
with different purposes (see [ 9] for a summary and more detailed analysis).
Problem. This diversity, although not necessarily pernicious, hampers the
progress of the i community. When reading a work around the i framework, it
is necessary first to understand what concrete version of i is being used. If the con-
tribution is based on the original framework, sometimes the authors declare which
version are they using (lately, it is happening to be the wiki version), but sometimes
there is no explicit mention, which usually makes the reader a bit hesitant about
details of the proposal being presented. Also it has to be said that the wiki ver-
sion is currently described as an informal tutorial (a users' guide) without providing
such a metamodel. On the other hand, if the work is proposing some new variation,
enrichment or customization of i , the semantics is sometimes given informally or
by using a formalism which is not easy to align with the available descriptions of
i . Therefore, as some authors explicitly claim [8, 46] , a unifying metamodel seems
amust.
Challenge. The i framework shall include one and only one metamodel; well-
established customization strategies for designing variants of this metamodel shall
be used.
State of the art. We may find in the literature several approaches of i meta-
models. Ayala et al. proposed a metamodel [ 6] that evolved into a more elaborated
one by Cares et al. [9] , see Fig. 1. It was designed by considering the features of
the original Yu's version [ 71] (which included its own metamodel written in Telos
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