Handling Conflicts in Aspectual Requirements Compositions - Transactions on Aspect-Oriented Software Development - page 163

Comparing the results just obtained (depicted in Table 17) with those obtained by
applying the AHP ranking (in Table 14) we can observe that both methods agree in
the first concern ranking, Validate Card. The 2 nd ranking for AHP is given to
Response Time and third to Multi-Access, while classical WA considers Multi-access
the 2 nd and Response Time the 3 rd priority. The two concerns have a high ranking but
Response time seems more essential in a system that deals with the public. The 4 th
place is the same for both approaches. There is an inversion regarding Accuracy and
Integrity, respectively 5 th and 6 th for AHP, versus 6 th and 5 th for classical WA. Again
the results of the AHP seem more appropriate because we need to ensure Accuracy
before being worried with Integrity. Fault Tolerance occupies the last position in both
methods.
Obviously, the classical WA method (1) is much simpler and provides good
enough results; however, it does not allow: using sound logical pairwise comparisons
(expressing different actors' preferences); consistency checks; and an easy
interpretable hierarchical representation with various levels (Fig. 4). Hence, the
choice between using this method or the AHP requires a decision between using a
faster and simpler method (although with direct classifications) versus using AHP,
which ensures pairwise psychological robustness, logical consistency and
interpretability.
To conclude, we should remember that since all MCDM problems are always ill-
defined [21] one should ensure that the classifications and weights of criteria reflect,
as much as possible, the users and developers opinions. Another problem, common to
all MCDM methods, is that big changes in the assigned classifications (both pairwise
or direct) may result in different rankings. Hence, the selection of a “good” MCDM
method should be done having in mind: the type of problem; the subjective nature of
classifications and their dependencies; the need to express preferences between
criteria and alternatives; check trade-offs between the advantages/disadvantages of
each method for the problem at hand. In this paper we compared two well-known
methods and discussed their results and respective advantages and drawbacks.
In summary, we can say that within subjective contexts, as is the case of resolving
conflicts in AORE in general, MCDM methods, despite their limitations, are a
suitable approach. Moreover, it seems that for resolving conflicts between concerns
the AHP method provides more robust and logical sound results, but with an overhead
of being a more time consuming method.
6 Related Work
Chung et al. propose a reasoning schema to detect and solve conflicting situations
between non-functional concerns [11]. However, this process does not support means
for a rigorous consistency checking neither does it offer a systematic trade-off
analysis technique. Yen and Tiao [25] presents a formal framework that facilitates the
identification and the trade-off analysis of conflicting requirements. This framework
describes a systematic approach for analyzing the trade-offs between conflicting
requirements using techniques based on fuzzy sets. However, again, there is no check
of consistency of priorities in order to minimize the errors during the decision
process.