Analysing the latency of WWW applications

The factors, which contribute to the latency experienced by users of WWW applications are analysed. A decomposition of latency into its constituent parts is undertaken and a methodology for determining the contribution of each element is presented. The methodology is illustrated in a case study of the traffic associated with an operational distributed learning environment (DLE) serving six universities over a period of several months. Quality is key to the success of DLEs, and this includes an understanding of their relationship with the underlying networks and systems technologies upon which they are built. Delay, 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. The analysis suggests that these techniques could be used as an early warning and advisory system for QoS aware applications