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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@walmsley.com
> Vitria Technology http://www.vitria.com
> Author, Definitive XML Schema (Prentice Hall PTR)
> ------------------------------------------------------------------
>
> > -----Original Message-----
> > From: Eddie Robertsson [mailto:eddie@allette.com.au]
> > Sent: Wednesday, January 30, 2002 5:34 PM
> > To: andrzej@chaeron.com
> > Cc: xml-dev@lists.xml.org
> > Subject: Re: [xml-dev] 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
> > >
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