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From Nicola Ken Barozzi <nicola...@apache.org>
Subject Re: Simplest possible way for dependency mapping?
Date Tue, 03 Dec 2002 00:25:26 GMT


Leo Simons wrote:
[...]
> 
> The right fix?
> --------------
> The question now is: how does one implement the dependency mapping that
> ServiceManager needs in the simplest way possible?
> 
> Some options crossed my mind:
> 
> - express dependencies as ordering inside a .properties file: all items
> that come below another one are allowed to depend on the ones above
> them. Bad because ordering of properties is not the way property files
> normally work and it adds additional semantics.

Actually this is the easiest and fastest way.
Don't want to use properties because of overloading semantics? Create a 
new file type and parse that:

component role=blah1   class=com.foo.blah1
component role="blah2" class="com.foo.blah2"


> - express dependencies in an ant-like fashion. Ie replace the properties
> file with something like
> 
> tweety.config
> -------------
> <component role="blah1" class="com.foo.blah1"/>
> <component role="blah2" class="com.foo.blah2"/>
> <component role="blah3" class="com.foo.blah3" requires="blah1,blah2"/>
> 
> this could set us on the road to complex container land.....

Not really. Since Tweety is a tutorial container, I would keep the 
"ordering" solution as a second tutorial step (Egg=0 Tweety=1), and 
implement this option for the third step.

It's quite easy unroll the aboce dependencies, and basically that's all 
there is to it, I don't see the "complex container land" problem.

> - dissallow dependencies, ie not support ServiceManager. The perceived
> added value of the framework goes to zero.

-0.9 yup, exactly

> - express dependencies in object form, ie:

-0.99 Java "extends" and "implements" are "it", if we need we read those

-- 
Nicola Ken Barozzi                   nicolaken@apache.org
             - verba volant, scripta manent -
    (discussions get forgotten, just code remains)
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