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From Stephen McConnell <mcconn...@apache.org>
Subject Re: ECM facility
Date Wed, 10 Mar 2004 11:10:55 GMT

[repost with correct recipient list]
Carsten Ziegeler wrote:

> Hi Stephen,
> I had a quick glance at your finder stuff but are absolutely clueless
> what I should do with it :) I guess from your description that if this
> finder is used inside Merlin I can use the ECM configuration files
> for defining my components. Is this right?

Sort of - the finder is just a privileged component running under (not
in) Merlin.  The main thing is that there is an ECM component that
declares a dependency on:

   (a) the finder component
   (b) a RoleManager component

Merlin will do what is necessary to startup the ECM component on demand.

> Is there any sample etc. that shows how to start Merlin including
> the finder?

Yep - its included in the /test directory.

First of all there is a block description which is supplied to merlin.
The block description declares the components that merlin should deploy.
In this scenario it includes the finder, a role manager (with a roles
configuration, and the ECM component with a master configuration.  The
block.xml can be found in /test/conf/block.xml.

There is a testcase the launches merlin using block.xml as the
definition of the application scenario.  The testcase does not currently
do much apart fro setting up the environment for doing a real test once
the implementation logic is put in place in under the ECM component.

Details for building are included in


Initial documentation is available here:


And javadocs here:


Cheers, Stephen.

> Carsten 
>>-----Original Message-----
>>From: Stephen McConnell [mailto:mcconnell@apache.org] 
>>Sent: Tuesday, March 09, 2004 2:20 AM
>>To: Avalon Developers List
>>Cc: dev@cocoon.apache.org
>>Subject: ECM facility
>>I've just committed some content into the merlin/facility 
>>directory dealing with a pull-based service finder 
>>implementation.  This commit is dealing with two things:
>>   (a) an example of the addition of a semantic extension to
>>       merlin without modification or extension to the container
>>       through the definition of a "finder" facility - the facility
>>       specifically address dynamic pull-based service activation
>>       (as per ECM and Fortress)
>>   (b) an experimental implementation of a ECM component - in
>>       particular a component that exposes the ServiceManager as
>>       its service interface
>>         - configurable with an ECM config file
>>         - dependent on a finder service
>>         - dependent on a RoleManager
>>       this RoleManager encapsulates the construction of a formal
>>       meta model implied by the ECM object model - in particular,
>>       the definition of the Role and Hint immutable data types
>>I've also put in place a test framework that will enable the 
>>testing and validation of a client invoking runtime requests 
>>for services backed by standard components (full 
>>meta-descriptors), together with ECM style solutions.
>>I'm not at the point where I need to start dealing with 
>>service requires
>>- and that means putting some content into some of the ecm 
>>component service methods - but more importantly - code 
>>dealing with the transformation of an ECM lookup argument 
>>into something that makes sense to the finder service is 
>>where the real ECM semantics will be captured.
>>The code is committed under:
>>    avalon/merlin/facilities/finder
>>This is composed of the following sub projects:
>>    * api  - definition of a Finder service interface
>>    * impl - definition of a default finder implementation
>>             that dynamically resolves services using
>>             avalon-composition
>>    * ecm  - skeleton implementation of an ECM service provider
>>             that deals with pure ECM role files and related
>>             configuration content
>>    * test - an initial test framework
>>At this point any help (code, tests, opinions, etc.) would be 
>>*very* much appreciated.
>>Cheers, Steve.
>>p.s. content is very initial
>>scope and potential for change is wide open
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