Actual implementation of passthrough

[Nicola Ken Barozzi <ni...@apache.org>]

If the @passthrough attribute is to be put in the <pipelines> section of 
the mounted sitemap, it seems easy: make the PipelinesNodeBuilder set a 
passthrough variable in the PipelinesNode, and have the PipelinesNode 
tell or not the last PipelineNode if it has to stop:

     public void setChildren(ProcessingNode[] nodes) {
         // Mark the last pipeline so that it can throw a
         //    ResourceNotFoundException
         //-> put an if() here
           ((PipelineNode)nodes[nodes.length - 1]).setLast(true);
         //
         super.setChildren(nodes);
     }

The point is that it makes sense for the mount node to set it, but I'm 
not sure which is the preferred way in the TreeProcessor to pass that 
info from the MountNodeBuilder to the PipelinesNode.

Suggestions?

-- 
Nicola Ken Barozzi                   nicolaken@apache.org
             - verba volant, scripta manent -
    (discussions get forgotten, just code remains)
---------------------------------------------------------------------

RE: Actual implementation of passthrough

[Carsten Ziegeler <cz...@apache.org>]

Sylvain Wallez wrote:

> 
> The passthrough information cannot be set on the processing 
> node, as it depends on the runtime environment (a single 
> sitemap can be mounted from different locations with 
> different values for passthrough).
> 
> IMO, the easiest way is for the mount node to set an 
> attribute in the Environment (which is private to the 
> pipeline machinery) that gets checked by the Pipelines node 
> of the mounted sitemap. That attribute should of course be 
> reset to its previous value upon return in the mount node.
> 
Hmm, I don't like adding tree processing information to the
environment :)
What about adding this info to the InvokeContext?

Carsten

Re: Actual implementation of passthrough

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

Nicola Ken Barozzi wrote:

>
> If the @passthrough attribute is to be put in the <pipelines> section 
> of the mounted sitemap, it seems easy: make the PipelinesNodeBuilder 
> set a passthrough variable in the PipelinesNode, and have the 
> PipelinesNode tell or not the last PipelineNode if it has to stop:
>
>     public void setChildren(ProcessingNode[] nodes) {
>         // Mark the last pipeline so that it can throw a
>         //    ResourceNotFoundException
>         //-> put an if() here
>           ((PipelineNode)nodes[nodes.length - 1]).setLast(true);
>         //
>         super.setChildren(nodes);
>     }
>
> The point is that it makes sense for the mount node to set it, but I'm 
> not sure which is the preferred way in the TreeProcessor to pass that 
> info from the MountNodeBuilder to the PipelinesNode.


The passthrough information cannot be set on the processing node, as it 
depends on the runtime environment (a single sitemap can be mounted from 
different locations with different values for passthrough).

IMO, the easiest way is for the mount node to set an attribute in the 
Environment (which is private to the pipeline machinery) that gets 
checked by the Pipelines node of the mounted sitemap. That attribute 
should of course be reset to its previous value upon return in the mount 
node.

WDYT?

Sylvain

-- 
Sylvain Wallez                                  Anyware Technologies
http://www.apache.org/~sylvain           http://www.anyware-tech.com
{ XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }

Re: Actual implementation of passthrough

[Nicola Ken Barozzi <ni...@apache.org>]

Unico Hommes wrote:
...
> What about letting MountNode catch the "No pipeline matched request" 
> exception that is thrown during processor.buildPipeline() and 
> processor.process() and decide whether or not to rethrow it there. Would 
> that work?

It could, but I'd have to check somehow that it's the right exception, 
as the end of the processing is not the only condition that triggers it.

Besides, Exception throwing is not necessarily fast and is not meant in 
itself to be used for flow management.

-- 
Nicola Ken Barozzi                   nicolaken@apache.org
             - verba volant, scripta manent -
    (discussions get forgotten, just code remains)
---------------------------------------------------------------------

Re: Actual implementation of passthrough

[Unico Hommes <un...@hippo.nl>]

Nicola Ken Barozzi wrote:

>
> If the @passthrough attribute is to be put in the <pipelines> section 
> of the mounted sitemap, it seems easy: make the PipelinesNodeBuilder 
> set a passthrough variable in the PipelinesNode, and have the 
> PipelinesNode tell or not the last PipelineNode if it has to stop:
>
>     public void setChildren(ProcessingNode[] nodes) {
>         // Mark the last pipeline so that it can throw a
>         //    ResourceNotFoundException
>         //-> put an if() here
>           ((PipelineNode)nodes[nodes.length - 1]).setLast(true);
>         //
>         super.setChildren(nodes);
>     }
>
> The point is that it makes sense for the mount node to set it, but I'm 
> not sure which is the preferred way in the TreeProcessor to pass that 
> info from the MountNodeBuilder to the PipelinesNode.
>
> Suggestions?
>

What about letting MountNode catch the "No pipeline matched request" 
exception that is thrown during processor.buildPipeline() and 
processor.process() and decide whether or not to rethrow it there. Would 
that work?

--
Unico