W3C home > Mailing lists > Public > www-qa@w3.org > February 2008

QA guidance on fragments

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Thu, 14 Feb 2008 14:00:40 +0000
Message-ID: <47B44988.1030403@hpl.hp.com>
To: "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
CC: www-qa@w3.org

Concerning ACTION-89

The document I had in mind was:


I think the introductory text is well worth consideration

As a general principle, variability complicates interoperability. In 
theory, interoperability is best when there are numerous identical, 
complete, and correct implementations. However, when compared to the 
alternatives, the net effect of conformance variability is not 
necessarily negative in all cases. For example profiles  subdivisions 
of the technology targeted at specific applications communities  
introduce variability among implementations. Some will implement Profile 
ABC, some will implement Profile XYZ, and the two might not 
intercommunicate well if ABC and XYZ are fairly different. However, if 
ABC and XYZ are subsets of a large monolithic specification  too large 
for many implementers to tackle in total -- and if they are well 
targeted at actual application sectors, then subdivision by profiles may 
actually enhance interoperability.

Different sorts of variability have different negative and positive 
impacts. The principal danger is "excessive" variability - variability 
that goes beyond what is needed for a positive interoperability 
trade-off and that unnecessarily complicates the conformance model. 
Specification editors need to carefully consider and justify any 
variability allowed and its affect on conformance. This can be done by 
referencing project requirements and use cases and/or explicitly 
documenting the choices made.

The whole thing is fairly concise and worth a read in my view.

In terms of the discussion we were having yesterday, I think that if 
there is substantial vendor interest in a particular fragment then that 
should provide adequate positive impact to counter the negative impacts 
- but that having too many fragments is likely to have the opposite effect.

Received on Thursday, 14 February 2008 14:01:10 UTC

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