Performance testing of communication protocols for three-tier computing: results for ICA and X window protocols

We present the results of performance tests to compare two protocols for three-tier computing using the Windows NT operating system. Three-tier computing features a data server for stored databases (Tier 1), an application server that runs applications (Tier 2), and a simple client program that runs on desktop machines that presents the user interface (Tier 3). Three protocols are available to communicate between Tier 2 and 3: intelligence computer architecture (ICA) with and without data compression, and X Window. We measured the performance of the three protocols in a multi-user environment in which we simulated the workload imposed by typical users. We found that, for Microsoft Office 97 and Lotus Notes applications, the X Window protocol uses approximately twice the network bandwidth of ICA, without compression. We also found that compressed ICA generates roughly one third less network traffic than uncompressed ICA at a cost of 20% of additional processor utilization.