The evolution of grid computing generates new requirements for distributed application development and deployment. There is no standard way of registering these applications, describing their input parameters and output results and monitoring their progress in the Grid environment. The Web Services Architecture (WSA) is an ideal technology to integrate legacy applications into the Grid. Adopting this service-oriented architecture, a model is implemented to achieve the dynamic deployment, scheduling and rescheduling of scientific applications. The model treats all components (Resource Service and Service Scheduler) as WSRF-compliant services which support the applications integration with underlying native platform facilities and facilitate the construction of the hierarchical scheduling system.