Re: [rules-dev] Issue with ResourceChangeScanner
Hi Steve - I have seen that issue before reported by others. But you
just explained the cause ! - I don't often use the classpath scanner
myself, so never thought of that.
Yes the lastModified being zero is a problem...
OK, well I think perhaps the solution would be if lastModified is not
a valid value, to NOT use that to decide availablility.
I think using a scanner on a classpath resource is a bit unusual to
start with, but it is possible in various containers to dynamically
change the classpath, so it kind of technically makes sense.
If I had things in the classpath, I would assume they are constant -
but I assume you are actually expecting the scan to pick up changes in
a future ?
(in the meantime, if you can avoid the classpath one that problem
should go away).
On Thu, Oct 8, 2009 at 5:53 AM, Steve Ronderos <steve.ronderos(a)ni.com> wrote:
Hello Dev List,
I encountered an issue today with my KnowledgeAgent removing resources from
its RuleBase shortly after creating it. I have the ResourceChangeScanner
running in my application.
I tracked the issue back to the scan() method in ResourceChangeScannerImpl.
It appears that the method is trying to identify resources that are no
longer available and remove them from both the RuleBase and future scans.
To do this it is checking lastModified on the resource and on a result of 0
removing the resource. The resources that I configured in my change-set
definitely still exist, but due to URL handler implementation provided by my
classloader, getLastModified always returns 0. (The resource I'm retrieving
is coming from a jar that is in my application's classpath and the URL
handler implementation is oracle.classloader.SharedCodeSourceURL)
Do you think it would be possible for the scan to identify unavailable
resources some other way than with the lastModified? and then if
lastModified is 0 maybe always or never update the resource? I'm not sure
what the best approach to that would be, but removing resources when their
lastModified is 0 seems incorrect to me.
Thanks,
Steve Ronderos
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Michael D Neale
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blog: michaelneale.blogspot.com