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negatively to each other, and have the same importance, need to be composed in the
same match point. For example, consider the case where a given module, which was
conceived to model or implement a given functionality of a system, needs to be secure
and to react in a very short period of time. Based on some catalogues, for example the
NFR Framework [11], security and response time contribute negatively to each other,
i.e. the more secure we want our module to be, the less fast it may become, and vice-
versa. This means that the system may not be able to satisfy both concerns with the
same degree of importance. Therefore, the satisfaction of these two particular
concerns may lead to a number of architecture choices that would serve their needs
with varying levels of satisfaction. A discussion about the side effects of this problem
can be found in [17]. For this reason, it is important to understand well each concern,
study the level of impact that each one may have on others and decide on their
relative importance before any solution decision is made. As explained in [17], the
optimal architecture is the one that involves architectural choices satisfying each
concern within some acceptable limits. These limits are derived from discussion with
stakeholders. The work presented in this paper aims at supporting such discussions
and subsequent negotiations.
It is worth pointing out that conflict management is a real problem, regardless of
whether or not one uses AOSD to handle it. The difference is that in traditional
software development methods, such as object-oriented methods, several distinct base
modules would need to include security and response time behaviors, while in AOSD,
both security and response time behaviors are modularized and each one implemented
as a separate aspect. Approaches like [1, 19] identify possible inconsistencies between
what is wanted and what is possible to meet. In other words, the selection process
encompasses the balancing of conflicting interests between stakeholders.
Considering that Multiple Criteria Decision Making (MCDM) techniques offer the
possibility to find, given a set of alternatives and a set of decision criteria, the best
alternative, the contribution of this paper is, therefore, to propose the use of MCDM
methods to support conflict management resolution. To solve MCDM problems many
types of techniques have been proposed (see for instance [25]): direct scoring and
ranking methods, trade-off schemes, distance-based methods, value and utility
functions, interactive methods. The selected method was the Analytical Hierarchical
Process (AHP) [20] with a simpler aggregation process [24]. The main reason why
the AHP method was selected is that it allows pairwise comparisons (a kind of trade-
off and interactive method), which seems appropriate to handle the kind of problems
in hand. Moreover, AHP helps guarantee the logical consistency of many human-
based judgments, as well as synthesizing a wide-range of data in a single solution.
The end result is a list of concerns ranked according to a set of criteria. This list of
ranked concerns will lead the choice of the system's architecture design, as previously
mentioned. In addition, we also compare the results obtained with the AHP method
with the classical weighted average decision matrix [21] to assess the selected
method.
This paper is organized as follows: Sect. 2 introduces an AORE model and briefly
introduces how other AORE approaches handle conflicts. Section 3 gives an overview
on MCDM. Section 4 discusses our proposal to handle conflicts in AORE, illustrates
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