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From Stephen McConnell <mcconn...@apache.org>
Subject Re: a view of the Avalon Container
Date Tue, 20 Aug 2002 13:52:18 GMT

Paul Hammant wrote:

> Stephen,
>>>  + If the handler requires another component, has a context and surely
>>>    will need a configuration, what is the difference between it and
>>>    a component?
>> None.
>> That's one of the fundimentatal difference between Merlin and 
>> Phoenix. Merlin is built using component oriented priocipals - 
>> Phoenix is a componet management system built using object oriented 
>> principals.  The difference is really significant.
> I'm not sure that is fair, the Phoenix impl is laced together in XML 
> allowing different components. 

The difference is that the component your referring to are restricted in 
terms of the lifecycle management.  For example, they cannot have 
depedencies. In contrast Merlin provides the container hierachy and the 
extension mechanism that both enable full unrestricted components to act 
as environment extensions.  For example, if you need a container 
providing "special-support" beyond normal component service dependecies, 
you can apply several different approach:

  * declare a container with depedencies (e.g. a container with a 
depedency on a transaction server)
  * create a container containing two sub-container - one for regual 
components and the other for internal services - you parent container 
can than make internal service available to the second container
   * add facilities via the extension mechanisms

In all cases, we are dealing with first-class components without any 

Cheers, Steve.


Stephen J. McConnell

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