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 setting features with core 4.4 | |||
Posted:
15-January-2008 12:34 Hello, I was trying to use some special features of the 4.4 API, but there I got some problems. When I try to set the isCombineForward feature I always get the same exception The PipelinedComparator comparator feature: http://deltaxml.com/api/feature/isCombineForward is not recognized What does this mean? With the isFullDelta, enhancedMatch1 and enhancedMatch2 features its working fine. For all for I use the method setComparatorFeature(featureName, featureValue) So can anyone tell me what I'm doing wrong? reguards Robert | |||
| compator vs combiner features | |||
Posted:
15-January-2008 14:46 Hello Robert,
This is because isCombineForward is a combiner feature, not a comparator feature. The combiner is a component which takes a raw, changes-only or minimal delta produced by the comparator and one of the other comparator inputs and a regenerate or 'recombine' to produce what was the other comparator input.
The software is working as we expect, I think you may have seen the list of features and did not appreciate the distinction between comparator and combiner? I'll see if there is anything in the documentation we can improve for a future release. Some backround to the API design: There is both an XMLComparator and an XMLCombiner in the lower level JAXP style API (in the com.deltaxml.api package). But there is only a PipelinedComparator in the higher level com.deltaxml.core API. The reason that we don't have a PipelinedCombiner is because when the comparator/combiner are used to 'round-trip' XML, the combiner needs raw un-processed delta files from the comparator. We have many use-cases for a Pipelined Comparator, but we could not find any for a 'Pipelined Combiner', hence the differences in these APIs. Regards, Nigel | |||
| compator vs combiner features | |||
Posted:
16-January-2008 12:33 hello nigel thanks for your fast reply. do i get you right? the combiner is used to reproduce a source document? so when i compare A and B and get the result C, then i can take B and C to get A again? regards robert | |||
| Re: compator vs combiner features | |||
Posted:
16-January-2008 16:43 Hello Robert,
Yes, exactly. A compare B -> C ; A combine-forward C -> B B combine-reverse C -> A Note that comparison is not commutative, so that: A compare B != B compare A Similarly this all works the other way round, so that: B compare A -> D ; B combine-forward D -> A A combine-reverse D -> B So the compareForward feature allows you to reverse the normal 'direction' of the delta when used with recombination. We don't believe we have many users of the combiner - though it does have some specialized use-cases, but it is an important way to prove the correctness of the delta; we use it heavily in our test processes. | |||
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