While most service-oriented solutions are developed for system integration or data integration, we propose a Web services-based solution, Eucalyptus, for provisioning applications and networks on demand. Eucalyptus is built on the power of the user-controlled lightpath provisioning (UCLP) tool, which pioneers a user-centric and service-oriented approach for creating and managing a private end-to-end optical network. As a first user of UCLP, Eucalyptus aims to construct an participatory environment for geographically distributed teams of architects and industrial designers with the with the support of configurable broadband switched networks, as well as the traditional routed IP networks. The contribution of Eucalyptus is to provide a proof-of-concept example on how Web service and service-oriented architecture (SoA) can effectively provide on-demand provisioning for heterogenous resources in hybrid networks. These resources can be provisioned, launched, monitored, terminated, and reserved through Web services. Eucalyptus is network and platform neutral. It offers a single point of entry for users to access resources ranging from video conference applications, rendering clusters, to the underlying networks. Each resource is configured through a resource-specific Web service. Eucalyptus also includes a set of generic management Web services to coordinate sessions, to manage resources and users, and to compose workflows, such that the network and the application are properly configured for the users engaging in a participatory design session.