Implementing Virtual Pipeline Components

[Vadim Gritsenko <va...@reverycodes.com>]

Hey guys,

Thanks to help of Sylvain :) I'd like to present this horrible hack which shows 
how VPC can be implemented, in particular example of Virtual Pipeline Generator. 
VPC generator is defined in the sitemap as:

   <!--
     - Virtual Pipeline Generator: Composed of other pipeline components.
     -->
   <map:generator name="virtual"
                  src="org.apache.cocoon.generation.VirtualPipelineGenerator">
     <map:generate src="welcome.xml"/>
     <map:transform src="welcome.xslt">
       <map:parameter name="contextPath" value="{request:contextPath}"/>
     </map:transform>
   </map:generator>

Later on, VPC generator can be used from any sub sitemap (as is the case with 
regular sitemap components) like this:

   <map:match pattern="x">
     <map:generate type="virtual"/>
     <map:serialize type="xhtml"/>
   </map:match>

All sources used in the definition of VPC generator will be resolved relative to 
the parent sitemap. All sources mentioned in the src attribute will be resolved 
relative to caller sitemap (example: <map:generate type="virtual" 
src="relative.xml"/>).

To see VPC generator in action, apply attached patch to the trunk and go to:
   http://localhost:8888/
   http://localhost:8888/samples/x


Now, there are several things which should be resolved to have proper implementaion:

   1. Figure out proper way of switching environment.
   2. Figure out how ComponentsNodeBuilder can access SitemapLanguage's
      manager's avalon sub-context.
   3. Implement caching
   4. Implement parameter passing & resolving
   5. Refactor classes implementing ProcessingPipeline


Help is welcome :)

Vadim

Re: Implementing Virtual Pipeline Components

[Sylvain Wallez <sy...@apache.org>]

Vadim Gritsenko wrote:

> Hey guys,
>
> Thanks to help of Sylvain :) I'd like to present this horrible hack 
> which shows how VPC can be implemented, in particular example of 
> Virtual Pipeline Generator.


<snip/>

> Now, there are several things which should be resolved to have proper 
> implementaion:
>
>   1. Figure out proper way of switching environment.
>   2. Figure out how ComponentsNodeBuilder can access SitemapLanguage's
>      manager's avalon sub-context.
>   3. Implement caching
>   4. Implement parameter passing & resolving
>   5. Refactor classes implementing ProcessingPipeline
>
>
> Help is welcome :)


Hehe, I spent the evening writing a long RT that we now have to turn 
into concrete code :-)

Sylvain

-- 
Sylvain Wallez                                  Anyware Technologies
http://www.apache.org/~sylvain           http://www.anyware-tech.com
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