The uncertain QoS management is gaining a lot of interest in the service oriented computing area. In this work, we propose a framework that allows to select the TopK compositions of services that best meet the user’s requirements. This framework not only handles the user’s global constraints but it also takes into account the fluctuating nature of the QoS informations. More specifically we present two algorithms that ensure the aforementioned purposes. The first one ranks the services of each abstract class according to the probabilistic dominance heuristic. The second one explores the compositions search space by leveraging the backtracking search. The experimental evaluation shows that the proposed heuristic is more effective than the ranking based on average QoS.