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Priscilla Walmsley wrote: > > This content model is infact invalid. In XML Schema you're > > not allowed to declare > > multiple elements with the same name and type in the same > > content model. This is > > Actually, you are allowed to have two element declarations with the same > name in the same content model, provided that they have the same type. In > this case, they have different types, rendering it invalid. Ooops, that's what I meant. Sorry, for the confusion ;-( Cheers, /Eddie > Even if they did have the same type, though, it is also invalid because it > is non-deterministic. The third element declaration has minOccurs="0", so > if you encountered a "characteristic" element as the third element, you > would not know if it matched the third or fourth declaration. > > Using your other example, I would recommend the following approach: > > > > > <library> > > > > <journal>...</journal> > > > > <journal>...</journal> > > > > <hardback>...</hardback> > > > > <book>...</book> > > > > <book>...</book> > > > > </library> > > Or, as Eddie said, you could define types named "journal", "hardback", > "book", etc. and have them all inherit from an abstract "publicationType". > Then use type substitution via xsi:type to indicate in the instance what > type they are. > > > > > <library> > > > > <publication xsi:type="journal">...</publication> > > > > <publication xsi:type="journal">...</publication> > > > > <publication xsi:type="hardback"/>...</publication> > > > > <publication xsi:type="book"/>...</publication> > > > > <publication xsi:type="book"/>...</publication> > > > > </library> > > Hope that helps, > Priscilla > > ------------------------------------------------------------------ > Priscilla Walmsley priscilla@w... > Vitria Technology http://www.vitria.com > Author, Definitive XML Schema (Prentice Hall PTR) > ------------------------------------------------------------------ > > > -----Original Message----- > > From: Eddie Robertsson [mailto:eddie@a...] > > Sent: Wednesday, January 30, 2002 5:34 PM > > To: andrzej@c... > > Cc: xml-dev@l... > > Subject: Re: Non-deterministic schema issue.... > > > > > > Hi, > > > > > This exchange came up on a different newsgroup. Anyone > > > know what the correct answer is? > > > > > > > > > MSXML4 is complaining about the schema below, saying > > that it is > > > > > > non-deterministic - i cant work out precisely why. > > > > > > > > > > > <xsd:sequence> > > > > > > <xsd:element name="characteristic" type="chartype1" > > > > > > maxOccurs="unbounded"/> > > > > > > <xsd:element name="characteristic" type="chartype2" > > > > > > maxOccurs="unbounded"/> > > > > > > <xsd:element name="characteristic" > > type="chartype3" minOccurs="0" > > > > > > maxOccurs="unbounded"/> > > > > > > <xsd:element name="characteristic" type="chartype4" > > > > > > maxOccurs="unbounded"/> > > > > > > </xsd:sequence> > > > > > > > > > This content model is infact invalid. In XML Schema you're > > not allowed to declare > > multiple elements with the same name and type in the same > > content model. This is > > the reason for MSXML4's error message. If the different types > > can be derived from > > a common base type you can solve this by using the xsi:type > > [1] attribute in the > > instance document but otherwise you have to declare the > > elements with different > > names. > > > > Cheers, > > /Eddie > > > > [1] http://www.w3.org/TR/xmlschema-0/#UseDerivInInstDocs > > > > > > > > > > The problem is probably because of the minOccurs=0 on the third > > > > > element. There is no way to know if the third element in such a > > > > > sequence is of type 3 or 4 without doing a read-ahead > > of it's child > > > > > elements. I don't think that Parsers read-ahead typically. > > > > > > > > But the minOccurs shouldnt be causing a problem. For > > starters, if we get rid > > > > of the minOccurs, the parser still complains. Are you > > saying that a schema > > > > enforcing the instance below would be non-deterministic > > because all the > > > > elements in the sequence have the same name? > > > > > > > > <library> > > > > <publication type="journal">...</publication> > > > > <publication type="journal">...</publication> > > > > <publication type="journal">...</publication> > > > > <publication type="hardback"/>...</publication> > > > > <publication type="book"/>...</publication> > > > > <publication type="book"/>...</publication> > > > > <publication type="book"/>...</publication> > > > > <publication type="book"/>...</publication> > > > > <publication type="reference"/>...</publication> > > > > <publication type="misc"/>...</publication> > > > > <publication type="misc"/>...</publication> > > > > </library> > > > > > > > > > > > > How else do you get around this? Giving each element a > > unique name would be > > > > a little silly, especially when there could be hundreds > > of them. besides.. > > > > if you then wanted to transform the XML into some HTML > > (as i do).. it would > > > > be much trickier. > > > > > > Andrzej Jan Taramina > > > Chaeron Corporation: Enterprise System Solutions > > > http://www.chaeron.com > > > > > > ----------------------------------------------------------------- > > > The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > > > initiative of OASIS <http://www.oasis-open.org> > > > > > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > > > > > To subscribe or unsubscribe from this list use the subscription > > > manager: <http://lists.xml.org/ob/adm.pl> > > > > > > ----------------------------------------------------------------- > > The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > > initiative of OASIS <http://www.oasis-open.org> > > > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > > > To subscribe or unsubscribe from this list use the subscription > > manager: <http://lists.xml.org/ob/adm.pl> > > > >
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