Loadrunner is a load test tool. It works at the protocol level, so you can use it to apply load to any webserver running on any platform. It generates the most useful information if it can also MONITOR the server you are loading so that it can provide you with information that shows sever performance at any given point during the test run, and spike in server load can be more directly related to a give action being performed.
I've never used it against Jboss so I don't know what level of monitoring is provided in that situation.
Properly designing and implementing a load test is something that takes training and experience to get right. I might suggest hiring a trained experienced Loadrunner expert to guide you through using the tool, that or go through the official training from a Mercury Certified Product Instructor
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