The capability to easily find useful services (software applications, software components, scientific computations) becomes increasingly critical in several fields. Current approaches for services retrieval are mostly limited to the matching of their inputs/outputs possibly enhanced with some ontological knowledge. Recent works have demonstrated that this approach is not sufficient to discover relevant components. In this dissertation we argue that, in many situations, the service discovery should be based on the specification of service behavior. The idea behind it, is to develop matching techniques that operate on behavior models and allow delivery of partial matches and evaluation of semantic distance between these matches and the user requirements. Consequently, even if a service satisfying exactly the user requirements does not exist, the most similar ones will be retrieved and proposed for reuse by extension or modification. To do so, we reduce the problem of behavioral matching to a graph matching problem and we adapt existing algorithms for this purpose. <br /><br />Motivated by these concerns, we developed the WS-BeM platform for ranking web services based on behavior matchmaking, which takes as input two WSCL or BPEL protocols and evaluates the semantic distance between them. The prototype is also available as a web service. Furthermore, an application is described concerning the tool for evaluating the effectiveness of the behavioral matchmaking method.