ClassLoader-based Shielding of Instrumented Classes

Need demo code showing how it is possible to have a [login to view URL] agent NOT see the instrumentation it applies to standard JDK classes. This ought to be possible with some ClassLoader magic. Your task, should you be so clever to find a working solution, is to show us how it's done. (clearer spec follows) ## Deliverables Requirements for ClassLoader-based shielding of instrumented classes (C) Copyright Software Pearls BVBA, v1.0 30-Jan-2009 We have a standard java.lang.instrument-compatible instrumentation Agent. This agent instruments incoming JDK classes. We would like to be able to have the agent **not** see any changes it makes to instrumented classes. For example, let's say our agent instruments [login to view URL], then we want the agent itself to keep "seeing" (using) the non-instrumented (ie original) [login to view URL], while the target application our agent is attached to, does end up seeing the instrumented String. We believe that a separation of class spaces should be achievable via some ClassLoader usage. Maybe a simpler solution even exists via the various classpath-related JVM command line arguments. You probably will have prior experience of the [login to view URL] package, and have written ClassLoaders before. The acceptance test for this project could be as follows (anything simpler, but which totally proves the sought after separation of "universes" will also satisfy us): your demonstration agent would instrument some as yet not loaded class (eg an obscure, rarely used JDK class) to add some "tracer" logic, eg to make the JVM beep every time toString() is called on an instance of the class. After instrumenting the class, the agent would instantiate the class, and call toString() itself. The agent's call to toString() should **not** result in a beep, proving that the agent keeps seeing the original class. A demo application for the acceptance test does the same instantiation logic as the logic, and calls toString(). That logic **should** produce a beep, proving that the target application does see the instrumented class.