Case Study 1: Retail Bank Internet Project

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Whitney Associates helped a large retail bank implement a business-critical system and ensured that user response time requirements were met. The system developed consisted of a customer database held centrally on a mainframe, but accessed via the company's intranet. The technologies involved were Web Browsers, Windows NT and OS 390.

Whitney Associates was involved in this project from its initial design through to its deployment. Initially, Whitney Associates assisted in the production of a spreadsheet model to confirm that the proposed architecture was capable of meeting the performance requirements. At this early stage it was discovered that, because of the capacity of the WAN link between users and central servers, the proposed size of the Web Pages was much too large and would have to be minimized. The discovery of such a critical oversight so early in the project lifecycle prompted the project leader to say "that we [Whitney Associates] had paid for ourselves in less than 2 weeks."

Next, a more detailed model was produced using a simulation tool called SES/strategizer. This model gave a better understanding of the dynamics of the system, e.g. priority, scheduling, business process, etc. and helped identify performance weak points. One weak point that was discovered was the time needed to make a secure connection and this led to some design changes to ensure that once the connection was made it could be open for as long as possible. It also allowed performance budgets to be assigned to each software component so that each developer knew what response time was to be expected from his code. The model was backed up with data gathered from the prototype test bed to increase the accuracy of the model predictions.

Testing of large scale distributed systems is very difficult and therefore the approach taken was to perform some performance tests and use the model to extrapolate the end-to-end response times. This allowed the performance testing time and effort to be reduced. In addition to the above activities Whitney Associates also advised on what metrics to collect once the system was operational and what monitoring should be performed to enable performance troubleshooting to be performed effectively.