If compared with J2EE, could we say components in
Avalon is similiar with J2EE conceptually? For
example, if we have a Avalon version of Pet store
compared with J2EE version, should we design most of
the entities such as ShoppingCart, Product, Customer,
etc. as components?
Dennis.
--- Stephen McConnell <[EMAIL PROTECTED]> wrote:
>
>
> Dennis Kang wrote:
>
> >Is there any design principle when to use
> components
> >and when to use general classses?
> >
>
> I tend to view things in less absolute terms:
>
> 1. there are objects that have no component
> notions
> 2. there are object that leverage component
> notions
> but are not pure compoennts (i.e. not
> deployable
> within a particular "standard" container
> 3. there are pure components which are typiclly
> targetted towards deployment under a "standard"
> containment environment
>
> Example of case 2:
>
> public class MyClassLoader extends URLClassLoader
> implements LogEnabled
> {
> Logger m_logger;
>
> public MyClassLoader( URL[] urls )
> {
> super( urls );
> }
>
> public void enableLogging( Logger logger )
> {
> m_logger = logger;
> }
> public Logger getLogging()
> {
> return m_logger;
> }
> }
>
> However, it does not take much to turn our example
> classloader object
> into a full component. All that is needed is a null
> argument constructor.
>
> In reality you have
>
> OOP -- grey zone -- COP/SOP
>
> Being grey should not be considered a bad thing -
> sometime you need a
> little tone in life.
>
> :-)
>
> Cheers, Steve.
>
>
> >
> >Thanks.
> >Dennis.
> >
> >__________________________________________________
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>
> --
>
> Stephen J. McConnell
>
> OSM SARL
> digital products for a global economy
> mailto:[EMAIL PROTECTED]
> http://www.osm.net
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