Online experimentation allows students from anywhere to operate remote instruments at any time. This promising e-learning application is well positioned to use Web Services to conduct online experiment systems due to its interoperability and Internet compliance. We present a double client-server architecture for online experiment systems and the methodology to wrap the functions of instruments into Web Services. We propose that the instrument Web Services should be stateful services and we present the framework to manage the states of the instrument web services. We benchmark the performance of this system when using SOAP as the wire format for communication and propose solutions to optimize performance.