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From Marc Portier <>
Subject Re: [RT] Virtual Sitemap Components
Date Fri, 16 Jul 2004 22:32:51 GMT

Sylvain Wallez wrote:

> Stefano Mazzocchi wrote:
>> Sylvain Wallez wrote:
>>> Carsten Ziegeler wrote:

<snip />

>>>> There were some mentions in the past, that a VSC can contain any 
>>>> sitemap
>>>> component, so even actions, matchers and selectors are allowed in
>>>> the definition of the VSC.
>>>> So, first question is: do we want this?
>>>> (I would say: no)
>>> I would say yes! Forbidding control structures in virtual components 
>>> would greatly reduce their usefulness.
>> i agree with you, but do you think it makes sense to use everything? I 
>> would say that just selection and action would be useful, but matching 
>> and redirection would be harmful.
> I don't see how matching could be harmful if selection is not, as 
> they're close to each other and only do tests on the environment.
> Redirects, actions and flowscript calls, however, break the semantics of 
> pipeline components which should not modify the system state, at least 
> until the pipeline execution starts.

again from the user/contract perspective:

redirects don't match any of isAGenerator, isATransformer, isASerializer 
so should be ruled out in any of those type of virtual components

if allowed at all, they could only make sense in something like a 
virtual-read (which as Vadim suggests (at least if I got that right) 
could be the second live of resources?)

flowscript calls fall under the same observation?

striclyt speaking actions don't I think: even with an action in place 
you can assure to be building up a part of a pipe that functions as a G, 
or T, or S

however, I wouldn't, from a user prespective, be surprised if for 
technical reasons the flexibility of these virtual components would be 
limited and exclude the use of actions

> Calling a resource should be possible, even if resources make less sense 
> with virtual components, provided that the resource contents follow the 
> rules for a virtual component.

I'm with Vadim here: resources v2 should be virtual-reads building up 
complete pipes, I see no other use if VPC's are there

Marc Portier                  
Outerthought - Open Source, Java & XML Competence Support Center
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