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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: Question about using URLClassLoader and Derby
Date Mon, 14 Nov 2005 19:34:29 GMT
Hi,

On Nov 14, 2005, at 10:58 AM, Kathey Marsden wrote:

> Binod.Pg@Sun.COM wrote:
>
>> BTW, where would your application run? I am assuming it is outside of
>> any managed environment like application server.
>
> Well, probably the farthest I might take a practical implementation
> myself  is to make some upgrade tests for Derby, but I want to provide
> an example of how to load Derby in a ClassLoader so that  a component
> that embeds Derby can run in any environment  without
> interference or interfering others.   For example,  lets say my
> component  was something that you could embed in your application  
> to add
> a  dictionary capability.  I'd like you to use my component, be  
> able to
> use Derby however you want to,  and be able to run in any  
> environment at
> all without even knowing that I use Derby.  I also want to make  
> sure the
> dictionary API  always uses the derby jars that I shipped and used for
> my QA.
>
> I think the System properties can  create  a  problem  for application
> servers too that might want to allow connection to different  
> versions of
> Derby.

I agree that a tricky part is how to specify properties for the  
different Derby databases that use different code bases. There is  
only one System Properties for a VM, and it's nailed pretty tight  
(you have to have privileges just to look at them!).

Maybe the answer is for the Derby instance bound to the class loader  
to be passed the Properties that it would normally look for in System  
Properties. So instead of DataSource newDataSource(ClassLoader  
loader, String databaseName) it could be DataSource newDataSource 
(ClassLoader loader, Properties  
whatWouldNormallyBeInSystemPropertiesIncludingDatabaseName).

Craig
>
>
> Kathey
>
>

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


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