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From Aaron Mulder <ammul...@alumni.princeton.edu>
Subject Re: Resource ref as dependency; WAS: Multiple Inheritance
Date Mon, 04 Oct 2004 02:02:20 GMT
	I just came across a similar problem that would be solved by this.  
I currently have a database configuration and an application 
configuration.  The database isn't directly in the dependency hierarchy 
for the application, but I passed it first on the command line and it 
worked OK:  "java -jar bin/server.jar DB app"

	The problem is that if I then run the server with no arguments, 
the app fails to start on account of the database not being ready.  Both 
entries were present in the var/config/config.list, so I assume it just 
started them out of order when I didn't maually provide the ordering on 
the command line.

	If it's going to be a long-term fix to implement the dependency 
strategy outlined in this thread, it may be worth putting in a quicker fix 
to preserve component ordering when writing to and reading from the 
var/config/config.list file.

Aaron

On Sun, 3 Oct 2004, David Jencks wrote:
> I agree, this is a good idea.  Lets have the default value for the flag  
> be "mandatory", i.e you only include the flag when it is optional.  We  
> can presumably do the same with ejb-refs from web apps to ejbs?  I  
> don't think we can have dependencies between ejbs since there can be  
> circular references.
> 
> david jencks
> On Oct 3, 2004, at 12:26 PM, Jeremy Boynes wrote:
> 
> > toby cabot wrote:
> >> On a (hopefully) related topic, what's the mechanism to declare the
> >> dependencies within an ear?  I ask because I've got a webapp that uses
> >> a connector and despite a <resource-ref> in web.xml and a
> >> <resource-ref> in geronimo-jetty.xml I get  
> >> javax.naming.NamingException: could not look up : env/ra/CF [Root  
> >> exception is java.lang.IllegalStateException: Proxy not returned.  
> >> Target  
> >> geronimo.server: 
> >> J2EEServer=geronimo,j2eeType=JCAManagedConnectionFactory,name=testCF  
> >> not started] when I start the server.  I assumed that the  
> >> <resource-ref> provided
> >> the dependency data to the server, but if there's some other technique
> >> I need to use I'll try that.
> >
> > I think this is a reasonable assumption - it certainly makes sense  
> > from the application's viewpoint.
> >
> > I should not be that hard to do - after all at deployment time we know  
> > all the references a component is making and what they will ultimately  
> > resolve to. Seeing as any attempt to use the resource will fail, then  
> > we might as well not start the component.
> >
> > The big downside I see is that it means a component won't start unless  
> > all its local references can be resolved. This could be an issue if  
> > there is logic in the code that chooses between references based on  
> > application-level criteria. Perhaps we should add a flag to the  
> > resource-ref that tags it as mandatory (we create a dependency) or  
> > optional (we don't).
> >
> > --
> > Jeremy
> >
> 
> 

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