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From David Van Couvering <David.Vancouver...@Sun.COM>
Subject Multiple systems in same VM -- does this really work?
Date Wed, 04 May 2005 22:23:13 GMT
Hi ,all.  I am getting questions we could use Derby inside a container 
such that each application in the container could have its own separate 
configuration.  In particular, it would be nice if each application 
(which often has its own classloader) could store its database files in 
a different location.

Based on previous discussions with Dan, my understanding is that 
conceptually you can have multiple Derby systems in a VM if you have 
each system created by a different classloader.  But since Derby system 
-wide properties are set using Java system properties, I don't think 
this could actually work.  Isn't it true that any  system-wide 
configuration (done either through -D or through System.setProperty) 
will apply for all Derby systems in the same VM?  Or does a system 
property apply only for the classloader of the class calling 
System.setProperty()?

Help here would be much appreciated.   I searched the Java SDK source 
code, but the method to load properties is a native method, and I can't 
find the native method source.  The fact that it *is* a native method, 
however, makes me suspect that system properties are VM-wide and not 
just classloader-wide.

Thanks,

David



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