extension strategy

[Stephen McConnell <mc...@apache.org>]

Arron's post on the Merlin Wish List

>Extensions
>*  Integrated JMX Support
>*  'exporter' for easy AltRMI exporting
>

Looking at the above two items - both relate to the area of container 
side extension.  In particular, the need for:

1. an internal container that establishes container facilities
   (e.g. a JMX or AltRMI exporter component) - as distinct from the
   current root user container

2. an extension equivalent to a container listener
   (so that things like exporters can harvest information from the
   model or during runtime deployment)

I've been doing a little thinking about its (1) over the weekend and 
figure its not tool difficult.  Today with have a single container 
root.  OK, so lets imagine we have a two root containers, one for user 
deployment and one for facilities.  The kernel will initiate a system 
container (probably from a kernel related definition), establish a 
system service manager, the deploy the user container.  When we do model 
construction and we are interested in the availability of modelization 
interceptors and modelization services (i.e. interceptors and services 
we plug-in dynamically to the model establishment process).  Equivalent 
concerns exist for assembly and deployment (interceptors and services).  
In all cases these resources are totally container-side concerns - never 
exposed to components directly.

Some examples:

1. A model listener checks meta-info and meta-data for attributes 
related to web-service capability and flags the component for subsequent 
deployment as a web-app.
2. A plug-in facility enables the potential for JMS notification of 
appliance state change.
3. A plug-in facility handles export of services to a JMX server.
4. anything else?

What's needed to achieve this?

1. introduce an even model in the the composition/model package
2. restructure the kernel to support server side facilities
3. define interceptors that enable modification and/or replacement of 
returned models
4. define listeners that leverage the container side event model

Is this consistent with the extension objectives in mind?

Cheers, Steve.

-- 

Stephen J. McConnell
mailto:mcconnell@apache.org




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