Architectural Foundations of WSRF.NET

State management has always been an underlying issue for large-scale distributed systems, but only recently has it been brought to the forefront of Grid computing with the introduction of the Web Services Resource Framework (WSRF) and its companion, WS-Notification. WSRF advocates standardized approaches for client exposure to and potential manipulation of stateful services for Grid computing; however, these arguments and their long-term implications have been difficult to assess without a concrete implementation of the WSRF specifications. This paper describes the architectural foundations of WSRF.NET, which is an implementation of the full set of specifications for WSRF and WS-Notification on the Microsoft .NET Framework. To our knowledge, the observations and lessons learned from the design and implementation of WSRF.NET provide the first evaluation of the WSRF approach. A concrete example of the design, implementation, and deployment of a WSRF-compliant service and its accompanying WSRF-compliant client are used to guide the discussion. While the potential of WSRF and WS-Notification remains strong, initial observations are that there are many challenges that remain to be solved, most notably the implied programming model derived from the specifications, particularly the complexity of service side and client code and the complexity of WS-Notification.