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From David Jencks <>
Subject Re: Updating a GBean's classloader
Date Tue, 28 Feb 2006 21:00:15 GMT

On Feb 28, 2006, at 12:39 PM, A. Zeneski wrote:

> I am attempting to implement a GBean to start up the Open For  
> Business suite of applications. Due to large number of libraries  
> involved we have some tricky ways of loading the application today.  
> Currently we have a small kernel which starts up (much like  
> Geronimo) and dynamically loads all the classes and builds a  
> initial classloader.
> From there, using this newly created classloader we startup the  
> server components, i.e. JOTM, Tomcat, etc. We are looking to move  
> away from this approach and instead of embedding these components  
> inside the application, we prefer to run the application inside a  
> container. Specifically Geronimo. Now that OFBiz has been accepted  
> into the Apache Incubator; I am motivated to get this done ASAP.
> What I have attempted to do first was just replace the context  
> classload on the current thread of the GBean and used a quick JSR88  
> implementation to deploy the web applications using this GBean as  
> the parent. However, the classloader obtained (after looking at the  
> GBean source code) is cached on the object itself and appears to be  
> immutable.
> My second attempt was based on code I found in the Kernel API.  
> After creating my classloader, I defined a new GBean (from inside  
> the initial GBean which does the classloading). I first grab an  
> instance of the Kernel:
> Kernel kernel = KernelRegistry.getSingleKernel();
> Then I attempt to:
> ObjectName ofb = JMXUtil.getObjectName(":role=OFBizCore");
> GBeanData ofbBean = new GBeanData(ofb, OFBLoader.GBEAN_INFO);
> kernel.loadGBean(ofbBean, cl);
> kernel.startGBean(ofb);
> Passing it the classloader *I* created (cl). I was hoping then that  
> if I configured the web applications to have the parent  
> ':role=OFBizCore' in their geronimo-web.xml configuration this  
> would set their servlet context classloader would be a child of the  
> classloader I created (loading the huge amount of classes/libraries  
> required).
> However, this bean (ofbBean) remains in the STARTING status and  
> never appears to start.

even if you get it to start I don't think this is likely to work well.
> Can anyone suggest to me a way to accomplish my goal.
> 1) Load all our classes in a dynamic way. I do not wish to copy all  
> libraries and configuration files into the standard Geronimo  
> repository.

I have to ask, why not put all the jars into the geronimo repo?  I  
think you will find that it really simplifies managing the  
dependencies.  however....
> 2) Load our web applications from their current location using the  
> classloader from #1. Our web applications are not in a single  
> location and are all expanded.

I think you need one of the features just implemented in the highly  
unstable 1.1 branch.  As of this morning, a web app uses a  
configuration classloader.  In particular, this means that the  
configuration classloader for a war includes all the jars from WEB- 
INF/lib and the WEB-INF/classes directory.  A consequence of this is  
that if you include the war configuration as a parent of some other  
configuration, the classes from the WEB-INF stuff will be available  
to the child configuration.  IIUC this is what you want.

If this is not what you need, please explain further.

While AFAIK the 1.1 branch works fine as of this morning, it is  
undergoing extensive rapid change and you shouldn't expect it to work  
at any particular moment for the next couple of weeks.

hope this helps
david jencks

> I am open to suggestions.
> Andy

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