The Web Services Management Layer (WSML) is an academic middleware platform that is placed in between clients and web services. It takes care of dynamic integration, selection, composition and client-side management of web services, thus removing the need to take care of these concerns in clients. This paper describes how the WSML can be used to express web service compositions, and presents the results of a number of experiments which evaluate the performance and scalability of the current WSML implementation. These results show that the WSML induces only a small overhead compared to systems in which the WSML has not been deployed. The advanced features of the WSML therefore come a low cost in terms of performance and scalability, which makes it a viable option in real-life web services applications.