I ran into a co-worker I had not seen in a while last week at IBM Software University 2006. He has a major US Bank as his customer. He told me how they were pushing the envelope of web services performance by running the WebSphere software stack on their mainframe using multiple (I think it was 13 of them) zSeries Application Assist Processors (zAAP) for the mainframe Java virtual machines. They just ran a performance test for a web service enabled IMS legacy system transaction. (SOAP messages over HTTPS in through the web/java/JCA/IMS layer and back) The workload was driven by the WebSphere Workload Simulator, recently renamed the Rational Performance Tester for zOS. The ran 1000 transactions per second while achieving a 0.1 second average response time. Granted, the bank does not have this in production but this sounds like a big step forward in web services performance to me.
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