State Management in .NET Web Services

In the paper, we identify a problem for certain applications wishing to use the web service paradigm to enhance interoperability: rapid, robust state maintenance. We classify two kinds of state: application state and session state. While many features are available to support session data, special mechanisms for application state maintenance are less well developed. Application state maintenance is integral to providing reliable, fault-tolerant web services. We discuss three different models to solve the problem and compare the advantages and disadvantages of each. Experimental results show that the choice of which model to use depends on application requirements. Many important emerging applications will involve the communication of potentially large time-sequenced data streams among heterogeneous clients with varying QoS requirements. D-Stampede.NET is an implementation of a system designed to support the development of such applications. We describe our web service implementation along with our state server solution to the application state management problem. A simple demo application is described and measured to validate performance.