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From Carsten Ziegeler <>
Subject Re: [Corona] PIpeline API
Date Mon, 14 Jul 2008 07:44:52 GMT
Reinhard Pötz wrote:
> I agree with you that the package structure should be cleaned up. It's 
> also a good idea to create a 'corona-pipeline-sax' module that contains 
> the SAX based components. I'm not so sure if we should really move the 
> pipeline implementations into their own modules. This seems to be too 
> much modularization for my taste. (The corona-pipeline.jar, that 
> currently contains the SAX components, is about 70kb only.)
Yes, I'm not concerned about the jar size itself, I'm concerned about 
dependencies. The ideal solution would be to have an api jar which has 
no other dependencies, perhaps one to a logging framework if we provide 
utility or abstract classes.

>> b) Actions should not be part of the pipeline api
>> I think we discussed this some time ago :) Removing actions from the 
>> pipeline stuff does not really hurt - they are invoked before the 
>> pipeline, so it shouldn't be too hard to build custom code which 
>> collects actions, assembles the pipeline, invokes the actions and then 
>> the pipeline.
> no objection ;-)
>> c) Pre and post processing
>> As the pipeline interfaces are not tied to sax or any other model 
>> (which is ok), there is no explicit notion of indicating that the 
>> processing starts or is finished - the latter is especially 
>> interesting for cleanup. So I think we should add these two lifecycle 
>> methods to the pipeline component interface.
> I don't see any problem either. Being curious, what are your use cases?
I've some pipeline components that open/close resources, like a JCR 
session for instance. If the contract includes that the pre and post 
processing methods are always called, the post processing method acts 
like kind of a disposal method where I can close my session.
I've other - in this sense rather obscure - use cases where the pipeline 
components need to pass information back to the caller before the 
processing starts. So the caller calls the pre processing method where 
the pipeline component adds something to the map, the caller can pick it 
up and then start the processing based in this information.

>> d) Splitting setup and execute
>> I would like to split the Pipeline#execute method into two, one for 
>> initialisation and one (without arguments) for executing.
> I was thinking about this myself because we need this separation also to 
> optimize conditional GET operations when the servlet URLs are involved.
Great :)

So how do we proceed? Do you mind if I start with the minor changes?


Carsten Ziegeler

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