Re: AW: variable dependencies on Components

Am Tue, 24 Aug 2004 13:29:01 +0200 schrieb Steinkamp Andre  
<[email protected]>:

> MyComponent now can get the dep1 and dep2 from the ServiceManager, but  
> what if i want a user to edit the block.xml and not the source code and  
> the .xinfo files? so he can add a new Component from MyService and  
> declare a new dependency with key="dep3". but in the service method from  
> MyComponent this dependency will never be fulfilled. so there is no  
> chance to style it variable!?

Ah, OK, now I see what you want to do. You can't use Serviceable anymore  
in that case. Look at the dynamics tutorial or simply at the following  
code, where I dynamically resolve a renderer that renders an e-mail body.  
Some notes: rendererPaths is taken from the configuration, container is  
taken from the context (key: urn:composition:containment.model type:  
org.apache.avalon.composition.model.ContainmentModel). My mail client will  
unfortunately break the formatting of the code for those using clients  
that don't support format=flowed.

rendererPath = rendererPaths[i].trim();
if ( log.isDebugEnabled() ) {
     log.debug("resolving renderer: "+rendererPath);
}
ReferenceDescriptor rdesc = new  
ReferenceDescriptor(BodyRenderer.class.getName(),
                                                     new Version(1, 0, 0));
DeploymentModel model = container.getModel(rendererPath);
if ( model == null ) {
     throw new MailerException("Configuration error: No component found at  
path "+rendererPath);
}
if ( ! model.isaCandidate(rdesc) ) {
     throw new MailerException("Configuration error: Component at path  
"+rendererPath+" doesn't match "+rdesc);
}
BodyRenderer renderer = null;
try {
     try {
         renderer = (BodyRenderer)model.resolve();
         if ( log.isDebugEnabled() ) {
             log.debug("Renderer "+rendererPath+" resolved to "+renderer);
         }
     }
     catch ( Exception exc ) {
         throw new MailerException("Unable to resolve component at path  
"+rendererPath, exc);
     }
     // body rendering, mail sending, etc.
}
finally {
     if ( renderer != null ) {
         if ( log.isDebugEnabled() ) {
             log.debug("Releasing renderer: "+rendererPath+"  
("+renderer+")");
         }
         model.release(renderer);
     }
}


cu & HTH,
    Raffi

-- 
The difference between theory and practice is that in theory, there is no  
difference, but in practice, there is.