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From "Reinhard Poetz" <>
Subject RE: [RT] Implementing Cocoon Blocks
Date Thu, 18 Sep 2003 19:09:11 GMT

From: Stefano Mazzocchi


>   3) persistent service behavior with hot deployment
> One of the big issues with hot deployment is the potentially 
> inconsistent state of the persistent services contained by one block 
> and used by another when the providing block is redeployed.
> The issue is easily solvable for block services provided via 
> sitemap by 
> imposing them as stateless services (or REST-like, by passing all the 
> required information every time).
> The problem appears evident for component instances.
> It is suggested that blocks don't allow direct classloading between 
> blocks, but that only components exposed in the block deployment 
> descriptor will be made available to other blocks. This way, all the 
> dependencies are known because all the component loading happens thru 
> the Block Manager and the block manager is able disposte and 
> reinstantiate all the blocks that contain instances of 
> components that 
> are in an inconsistent state.
> While it is possible to write a classloader which is smart 
> enough to do 
> the above even for transparent classloading (say, loading via "new 
> Blah()" instead of via cocoon.getComponent("Blah")), it is 
> suggested to 
> disallow direct classloading to avoid creating hidden 
> contracts between 
> blocks.

I understand that I can't load a class from another block. My question:
Is it possible to load classes from "Cocoon core" (whatever we will
consider as core) from within my block via "new" or are there arguments
against it?


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