Abstract
In this paper, we deal with two validation techniques which may be adopted for improving the quality and ensuring the correctness of Distributed Information Systems. These two techniques are Formal Verification and Model Based Techniques. The first one consists in checking the correctness of a mathematical model used to describe the behavior of the considered system before its implementation. The second technique consists in deriving tests suites from the adopted model, executing them and finally deducing verdicts about the correctness of this system under test. In both cases, we need to tackle the explosion state challenge which corresponds to the fact of reaching a very large space of states and consuming a very long time during the validation process. To solve this problem we propose a set of appropriate techniques taken from the literature. We also identify a set of techniques which may be used for the optimization of the test component placement procedure.