Web Services are universally accessible software units that are advertised, discovered, and invoked over the internet. As web service technology is becoming widely adopted by organizations that need to integrate their information systems within and across organizational boundaries, it is important to identify automatically relevant composable services. In this paper, we propose an approach based on a variant of Formal Concept Analysis for the identification of composable services. It allows the classification of web services according to their QoS and composability levels and proposes a query mechanism that allows users to specify their required QoS and composability levels.In the case of multiple choices that satisfy users' requirements, we enhance our approach with a mechanism based on vectors for identifying the optimized choice. We validate our approach on a set of real-world web services obtained from Service-Finder.