Determining the Sources of Delay in a Distributed Learning Environment

In the context of LeGE-WG we expect to see the Open Grid Services Architecture (OGSA) being used as a guiding framework for the future deployment of Distributed Learning Environment (DLEs). OGSA is totally service-oriented and it has been known for sometime that Quality of Service (QoS) is key to the success of DLEs. Delay in particular, as experienced by the end user, is one of the key QoS parameters for a DLE. This paper describes techniques for identifying sources of such delay, and a model for its analysis. Four major sources of delay are distinguished: Server, Client, Network and Protocol. The analysis techniques are illustrated in a case study of the traffic associated with a set of operational DLEs serving six Universities over a period of several months. This paper contributes towards the use of OGSA for e-learning by providing a detailed understanding of the QoS requirements for an OGSA compliant e-learning service.