Fault Isolation Load Testing. If your schedule allows, perform a load test of the back end server using the queries that would normally be generated by the middleware. Use the middleware and server logs to collect the queries and then run the queries through a query tool for the server while recording with VUGEN.
Run this load test for the expected number of users. Keep in mind, the client API for load testing is N-level ignorant. IT could just as easy be one level of server, as multiple levels of middleware - the client really only cares about the response and the response time.
After the DB is qualifies, then run your client level load test through the middleware server. This type of testing will provide the added benefit of allowing you to identify how much time is being spent (on average) in the middleware server -- you can then use this information for tuning purposes.
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