[rules-dev] Issue with ResourceChangeScanner

Fri Oct 9 12:35:54 EDT 2009

Michael,

I've logged the issue (https://jira.jboss.org/jira/browse/JBRULES-2293). I 
agree that classpath resources should not be scanned.  That would solve my 
immediate problem.

One last note, I still don't think that checking lastModified != 0 to 
determine existence is ideal, there could be other scenarios where the 
lastModified method is not implemented and returns 0.  Is there a better 
way to check for resource existence other than lastModified?

Thanks,

Steve Ronderos

rules-dev-bounces at lists.jboss.org wrote on 10/08/2009 05:13:17 PM:

> [image removed] 
> 
> Re: [rules-dev] Issue with ResourceChangeScanner
> 
> Michael Neale 
> 
> to:
> 
> Rules Dev List
> 
> 10/08/2009 05:14 PM
> 
> Sent by:
> 
> rules-dev-bounces at lists.jboss.org
> 
> Please respond to Rules Dev List
> 
> Hi Steve - ok - I am leaning towards insisting that classpath
> resources are not scanned for - just loaded once. There are cases
> where you can update a classpath value on the fly, but really, I think
> using file/database/http would be better for that sort of dynamic
> changes...
> 
> Please do log it as a bug, let us know and I will make it critical, as
> I think its kinda broken and not workable at the moment.
> 
> On Fri, Oct 9, 2009 at 12:46 AM, Steve Ronderos <steve.ronderos at ni.com> 
wrote:
> >
> > Michael,
> >
> > In this exact case I am not expecting the scanner to ever find an 
updated
> > resource; however, the changeset is configured to read one resource 
from a
> > URL and another from the classpath.  The resource from the URL is 
expected
> > to change, but the one from the classpath is not.  We have a use case 
where
> > we may need classpath resources to be scanned, but I'm not sure itwill 
ever
> > come up.
> >
> > Unfortunately I don't think that we can reference that resource any 
way
> > other than the classpath at this moment, but we do have another 
workaround.
> >  Previous to Drools 5 we had a custom way of refreshing our resources 
which
> > I think we will go back to for now.
> >
> > Should I log a feature request for this change?
> >
> > Steve Ronderos
> >
> > rules-dev-bounces at lists.jboss.org wrote on 10/07/2009 05:29:56 PM:
> >
> >> [image removed]
> >>
> >> Re: [rules-dev] Issue with ResourceChangeScanner
> >>
> >> Michael Neale
> >>
> >> to:
> >>
> >> Rules Dev List
> >>
> >> 10/07/2009 05:31 PM
> >>
> >> Sent by:
> >>
> >> rules-dev-bounces at lists.jboss.org
> >>
> >> Please respond to Rules Dev List
> >>
> >> 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 at 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
> >> > _______________________________________________
> >> > rules-dev mailing list
> >> > rules-dev at lists.jboss.org
> >> > https://lists.jboss.org/mailman/listinfo/rules-dev
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> Michael D Neale
> >> home: www.michaelneale.net
> >> blog: michaelneale.blogspot.com
> >>
> >> _______________________________________________
> >> rules-dev mailing list
> >> rules-dev at lists.jboss.org
> >> https://lists.jboss.org/mailman/listinfo/rules-dev
> >
> > _______________________________________________
> > rules-dev mailing list
> > rules-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-dev
> >
> >
> 
> 
> 
> -- 
> Michael D Neale
> home: www.michaelneale.net
> blog: michaelneale.blogspot.com
> 
> _______________________________________________
> rules-dev mailing list
> rules-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-dev
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