Automated web service composition is one of the major promises of service-oriented architecture, where services can be discovered and composed dynamically and automatically. To investigate the methods for composite web service construction, we conducted an experiment on creating useful composite web services from real existing web services where semantic annotations are not available. The empirical study reveals the difficulties and research challenges in the discovery, invocation, and composition of web services. The automation of web service composition requires the inputs from both services providers and service consumers. Service providers need to develop high quality services in a disciplined and collaborative way, and service consumers need to be equipped with tools providing helps such as service discovery and matching.