  The internet is considered as the most extensive market in the world. To keep
its gradual reputation, it must confront real problems that result from its
distribution and from the diversity of the protocols used to insure
communications. The Web service technology has diminished significantly the
effects of distribution and heterogeneity, but there are several problems that
weaken their performance (unavailability, load increase of use, high cost of
CPU time...). Faced with this situation, we are forced to move in the direction
of the substitution of web services. In this context, we propose an effective
technique of substitution based on a new method of matching that allows
detecting and expressing the matching between the web services pairwise by
considering that each of them is ontology. Also, our method performs a
discovery of the most similar web service to that to be replaced by using an
efficient method of similarity measurement.
