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From Berin Loritsch <blorit...@apache.org>
Subject Re: sitemap component selector (was: sub sitemap broken)
Date Tue, 19 Jun 2001 12:44:18 GMT
Torsten Curdt wrote:
> 
> > I also get the same error by requesting a page from the sub-sitemap with a ?cocoon-reload=true
parameter.
> >
> > > What I found out so far....
> > >
> > > 1) When I start with a clean repository everything seems to work...
> > > 2) Restarting Tomcat a second time shows the bug.
> > >
> > > I checked the SitemapComponentSelector. The parent selector is always set
> > > - never null. That's really strange!
> > >
> > > What's the difference to a clean repository?!
> 
> Berin, Giacomo,
> 
> I'm really trying to track this down but I need
> your guidance...
> 
> For my understanding: Where is the need of an hierarchical
> ComponentManager when we want to reuse components as good
> as possible? When a component is looked up and an instance
> is created, the instance is only available to the ComponentManager
> (and it's childs) that created it, right? But how does that make
> sense? When a component is created in a sub sitemap's ComponentManager
> why shouldn't this component also be reused in a different sub sitemap
> or the main sitemap? What did I miss to understand ?

What happens is that the ComponentManager will try to look up a Component
itself.  If it can't find it, it checks it's parent.  If the parent can't
find it, the original component manager will attempt to build it.  This
happens for each ComponentManager in the chain.

The Sitemaps do need their own ComponentManager due to security constraints,
and the fact that the ExcaliburComponentManager is Initializable now.  That
means that once it is initialized, it cannot add new components.

> In my last working version there was also only ONE ComponentManager
> for all sitemaps. My first humbled tries to go back to one ComponentManager
> failed. But before wasting time on this maybe one of you guys might
> spend a minute and entlighten me ;)

This was true.  But this is also before Excalibur made that design change.
You will find that the design change is also what enables the load on startup
of ThreadSafe Components (i.e. getting Daemon Components to run when the
ComponentManager is initialized.
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