Is double parentId inheritance allowed

[Jacek Laskowski <jl...@apache.org>]

Hi,

The question stroke me while I was updating PetStore configuration to 
the recent changes. The issue is that supplier ear needs to have a 
database, jms and security subsystems configured. The database and jms 
configurations are all about resourceadapters, but the security 
configuration introduces several GBeans. This led me to the question 
about parentId inheritance.

If I had two configurations (plans) with a bunch of GBeans and created 
another configuration that should have the GBeans from these two 
configurations available, how should I proceed? Is the only option to 
copy them to a single plan that will in turn be used as parentId?

Jacek

Re: Is double parentId inheritance allowed

[David Jencks <da...@yahoo.com>]

On Oct 25, 2005, at 2:35 PM, Jacek Laskowski wrote:

> David Jencks wrote:
>> We now have multiple parents in a configuration.  You can specify the 
>> first one with the parentID attribute.  The other need to be the 
>> first elements in the plan,
>
> Thanks Dave! That was it!
>
> petstore:start:
>     [echo] Waiting for server at: 
> c:\projs\geronimo\sandbox\petstore/target/geronimo-1.0-SNAPSHOT
> Booting Geronimo Kernel (in Java 1.4.2_09)...
>     [echo] PetStore has started
> BUILD SUCCESSFUL
> Total time: 59 seconds
> Finished at: Tue Oct 25 23:31:28 CEST 2005
>
> Just curious, what made you think it's going to be necessary? Is it 
> already used somewhere?

Yes, very very heavily.  As soon as I started thinking about how to 
break up the giant monolithic server plan into smaller pieces it became 
really clear that a configuration has to be able to get classes from 
many parent classloaders.  Fortunately Dain had just developed the 
classloader we needed :-)  I think in the post-geronimo-1.0 timeframe 
we may be getting an even better system that uses OSGI classloaders.
>
> I also wonder about the single vs multiple parent issue in a 
> configuration. I can't describe one at the moment, but I guess there 
> might be some where two GBeans are defined in two configurations and 
> one would need to inherit them to create a new one. Which GBean would 
> win?

Be careful to distinguish between a gbean's implementation class and an 
instance of it.  You want to be very very careful to make sure the 
class is only loaded in one classloader, but numerous configurations 
that are descendants of that configuration can have instances of the 
gbean.
>
> BTW Which module is it in? I'm going to test it out in some unit tests 
> to see if there's anything I should really be concerned about.

The MultiParentClassLoader is in the kernel module.  There are some 
examples of multiple parents in the plans we supply, but the main use 
is really for e.g. ears: an ear with a jetty web app and some ejbs 
would have the jetty and server configs as parents.  See especially the 
defaultParentIds in the various module builders.

Hope this clears things up a bit
david jencks

Re: Is double parentId inheritance allowed

[Jacek Laskowski <jl...@apache.org>]

David Jencks wrote:
> We now have multiple parents in a configuration.  You can specify the 
> first one with the parentID attribute.  The other need to be the first 
> elements in the plan,

Thanks Dave! That was it!

petstore:start:
     [echo] Waiting for server at: 
c:\projs\geronimo\sandbox\petstore/target/geronimo-1.0-SNAPSHOT
Booting Geronimo Kernel (in Java 1.4.2_09)...
     [echo] PetStore has started
BUILD SUCCESSFUL
Total time: 59 seconds
Finished at: Tue Oct 25 23:31:28 CEST 2005

Just curious, what made you think it's going to be necessary? Is it 
already used somewhere?

I also wonder about the single vs multiple parent issue in a 
configuration. I can't describe one at the moment, but I guess there 
might be some where two GBeans are defined in two configurations and one 
would need to inherit them to create a new one. Which GBean would win?

BTW Which module is it in? I'm going to test it out in some unit tests 
to see if there's anything I should really be concerned about.

> david jencks

Jacek

Re: Is double parentId inheritance allowed

[David Jencks <da...@yahoo.com>]

We now have multiple parents in a configuration.  You can specify the 
first one with the parentID attribute.  The other need to be the first 
elements in the plan,

<import>
   <uri>o/a/g/2ndparent</uri>
</import>
<import>
    <groupID>org.apache.geronimo</groupID>
    <type>car<type>
    <artifactID>foo</artifactID>
    <version>1.0</version>
</import>

are a couple of the styles allowed.

thanks
david jencks

On Oct 25, 2005, at 1:08 AM, Jacek Laskowski wrote:

> Hi,
>
> The question stroke me while I was updating PetStore configuration to 
> the recent changes. The issue is that supplier ear needs to have a 
> database, jms and security subsystems configured. The database and jms 
> configurations are all about resourceadapters, but the security 
> configuration introduces several GBeans. This led me to the question 
> about parentId inheritance.
>
> If I had two configurations (plans) with a bunch of GBeans and created 
> another configuration that should have the GBeans from these two 
> configurations available, how should I proceed? Is the only option to 
> copy them to a single plan that will in turn be used as parentId?
>
> Jacek
>