Getting references to the objects in a VM to dynamically link MBeans
Hi, I am dynamically generating MBeans and using Apache BCEL to change the resource classes to link themselves to the MBeans. The objective is to instrument applications wich we can't access the code and, if possible, do it on a running one.
I could use the Instrumentation API to change the classes of the application and the Attach API to do it on a running application, but only new instances would be affected, so the previously created objects would not be managed. I can generate MBeans in many ways, but can't link them to already running application objects.
So, what i want to know is in the title: is there a way to get references to the objects actually loaded in a Virtual Machine or another way to link an MBean to a running object?
I saw McManus talk at Sun One 2006 about the different ways to link MBeans to application objects, but all of them look to need code changes or previous suport to dependency injection, for example.
http://developers.sun.com/learning/javaoneonline/2006/coreplatform/TS-3523.html
I need it to a technical writing, so an official word can be enough, or even more helpful than a solution.
Thanks,
Gustavo
Gustavo,
Assuming I understand your question correctly, the only way I can see that you can enumerate instances of objects in a Java VM without changing the classes of those objects in any way is to use JVMTI <http://java.sun.com/javase/6/docs/platform/jvmti/jvmti.html#Heap_1_0>. That requires you to write native code somewhere as part of your solution. It is applicable to already-running apps via attach-on-demand <http://java.sun.com/javase/6/docs/jdk/api/attach/spec/index.html>. The MLet service from the JMX API might be convenient here to bridge from the jar file that the Attach API expects to the native code that you need to access JVMTI.
As you can see this is pretty advanced stuff, but your ideas are interesting and I'd be interested in knowing how they work out.
Regards,
�amonn McManus -- JMX Spec Lead -- http://weblogs.java.net/blog/emcmanus
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COMPONENT STORE TRANSACTION DETAILS
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Sunil -
Reference to C# objects in TestStand - how to save and retreive them
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Message Edited by Jon M on 11-01-2006 12:44 PM
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