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From Grzegorz Kossakowski <g...@tuffmail.com>
Subject Re: [C3] Pipeline component event types
Date Tue, 13 Jan 2009 12:43:48 GMT
Grzegorz Kossakowski wrote:
> Reinhard Pötz wrote:
>   
>> I don't believe that pipelines should contain components that support
>> different event types or that we event need components that have
>> different input and output events.
>>   
>>     
> What about serializer? Usually, it produces events of a type different
> from the type of events it consumes.
>   
>> If you want to mix your components (e.g. using a SAX component in a
>> pipeline full of StAX components), you should put your 'alien' component
>> into a wrapper.
>>   
>>     
> Agreed. How do you know what kind of wrapper do you need if you don't
> know what kind of events components consume and produce?
>
> How component can be sure that next component (its consumer) is the one
> that accepts right type of events? By checking using instanceof?
> My point is that once we agree to have generic pipelines that can take
> components accepting/producing any kind of events then we need to invent
> some mechanism that check if pipeline is built correctly. It shouldn't
> be a concern of a given component.
>
> If we agree on above point, then my suggestion would be to look for a
> way that pipeline-correctness is ensured by compiler.
>   
One more thing:
The idea that pipeline does know about event types that components
process solves the problem with pipeline results as you have different
event type carrying different data.


-- 
Best regards,
Grzegorz Kossakowski

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