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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XSD elementFormDefault="unqualified" destroys the benefits
 Hi Roger, The first instance imply 4 schemas (you need a different schema for each namespace). The second instance cannot be obtained by setting the elementsFromDefault to unqualified in all these 4 schemas so I believe all the outcome further is irrelevant having a false presumption. The second instance can be the result of a single schema that has elementFormDefault (or the form attribute on each local element) set to unqualified but that is a totally different thing than having 4 schemas. Best Regards, George -- George Cristian Bina <oXygen/> XML Editor, Schema Editor and XSLT Editor/Debugger http://www.oxygenxml.com Costello, Roger L. wrote: > Hi Folks, > > Recall that with XML Schemas you can specify that all elements in conforming instance documents must be namespace-qualified using: > > elementFormDefault="qualified" > > Or, you can specify that only top-level, global elements must be namespace-qualified using: > > elementFormDefault="unqualified" > > These can yield remarkably different instance documents. > > > INSTANCE #1 > > Here is an example of an instance where the schema specifies "qualified": > > <?xml version="1.0"?> > <c:camera xmlns:c="http://www.camera.org" > xmlns:nikon="http://www.nikon.com" > xmlns:olympus="http://www.olympus.com" > xmlns:pentax="http://www.pentax.com"> > <c:body> > <nikon:description>Ergonomically designed casing for easy > handling</nikon:description> > </c:body> > <c:lens> > <olympus:zoom>300mm</olympus:zoom> > <olympus:f-stop>1.2</olympus:f-stop> > </c:lens> > <c:manual_adapter> > <pentax:speed>1/10,000 sec to 100 sec</pentax:speed> > </c:manual_adapter> > </c:camera> > > > INSTANCE #2 > > Using the same schema, but specifying "unqualified," here is the instance: > > <?xml version="1.0"?> > <c:camera xmlns:c="http://www.camera.org"> > <body> > <description>Ergonomically designed > casing for easy handling > </description> > </body> > <lens> > <zoom>300mm</zoom> > <f-stop>1.2</f-stop> > </lens> > <manual_adapter> > <speed>1/10,000 sec to 100 sec</speed> > </manual_adapter> > </c:camera> > > > BENEFITS OF NAMESPACES > > Namespaces modularize instance documents. They enable applications to perform module-specific processing. > > > MODULES IN INSTANCE #1 > > In instance #1 the namespaces modularize the document. The document can be readily partitioned into these five modules: > > ------------------------------------------- > <c:camera xmlns:c="http://www.camera.org"> > <c:body> > </c:body> > <c:lens> > </c:lens> > <c:manual_adapter> > </c:manual_adapter> > </c:camera> > ------------------------------------------- > <nikon:description xmlns:nikon="http://www.nikon.com"> > Ergonomically designed casing for easy handling > </nikon:description> > ------------------------------------------- > <olympus:zoom xmlns:olympus="http://www.olympus.com"> > 300mm > </olympus:zoom> > ------------------------------------------- > <olympus:f-stop xmlns:olympus="http://www.olympus.com"> > 1.2 > </olympus:f-stop> > ------------------------------------------- > <pentax:speed xmlns:pentax="http://www.pentax.com"> > 1/10,000 sec to 100 sec > </pentax:speed> > ------------------------------------------- > > > MODULES IN INSTANCE #2 > > In instance #2 there is one namespace module and three no-namespace modules: > > ------------------------------------------- > <c:camera xmlns:c="http://www.camera.org"> > </c:camera> > ------------------------------------------- > <body> > <description>Ergonomically designed > casing for easy handling > </description> > </body> > ------------------------------------------- > <lens> > <zoom>300mm</zoom> > <f-stop>1.2</f-stop> > </lens> > ------------------------------------------- > <manual_adapter> > <speed>1/10,000 sec to 100 sec</speed> > </manual_adapter> > ------------------------------------------- > > > PROBLEMS WITH INSTANCE #2 > > The no-namespace modules are comprised of multiple XML vocabularies. For example, in the lens module the <lens> element comes from the camera schema, whereas the <zoom> and <f-stop> elements come from the olympus schema. > > An application written for the olympus schema would not be able to process the lens module for these two reasons: > > a. The elements are not associated with the olympus namespace. Consider how the olympus application would behave upon encountering the lens module: "Is that <zoom> element really the element I know about, or is it somebody else's zoom element? > > b. The olympus application knows nothing about the <lens> element. > > > RECOMMENDATION > > Don't use elementFormDefault="unqualified" in your XML Schemas. It destroys the modularity benefits provided by namespaces. > > > Do you agree with this recommendation? > > /Roger > > > > _______________________________________________________________________ > > XML-DEV is a publicly archived, unmoderated list hosted by OASIS > to support XML implementation and development. To minimize > spam in the archives, you must subscribe before posting. > > [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ > Or unsubscribe: xml-dev-unsubscribe@l... > subscribe: xml-dev-subscribe@l... > List archive: http://lists.xml.org/archives/xml-dev/ > List Guidelines: http://www.oasis-open.org/maillists/guidelines.php > 
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