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Re: [xml-dev] How to avoid the sequens of child elements in DTD, yet keep the cardinality?
Here is a rough Schematron schema for that. Note that the plain English statements
of requirements mostly map naturally into XPath statements. Note also that this
will scale well to add other consecutive new elements, whereas the DTD version
will explode.
Cheers
Rick Jelliffe
<schema xmlns="http://www.ascc.net/xml/schematron";>
<title>Schema for Albena Georgieva</title>
<pattern>
<rule context="Header">
<assert test="count(Identification) = 1"
>Header must have one and only one child element of type
Indentification</assert>
<assert test="count(Weight) <= 1"
>Header can have [0 ... 1] Weight children elements</assert>
<assert test="count(Category) > 0"
>Header must have at least one Category child element</assert>
<assert test="count(*) = count(Identification) + count(Category) +
count(Weight) + count(Keywords)"
>Header can have [0 ... n] Keywords</assert>
<assert test="count(Keyword) > 1 and
(Keyword[previous-sibling::*[self::Keyword] or next-sibling::*[self::Keyword]])"
>If there are several children of the same type Keyword, then they should be
following each other.</assert>
<assert test="count(Category) > 1 and
(Category[previous-sibling::*[self::Category] or next-sibling::*[self::Category]])"
>If there are several children of the same type Category, then they should be
following each other.</assert>
</rule>
</pattern>
</schema>
Cheers
Rick Jelliffe
From: "W. Hugh Chatfield I.S.P." <hchatfield@urbanmarket.com>
> Actually we have the technology - we can build this:
>
> <!ELEMENT Header ((Identification,((Weight,((Category+,Keywords+) |
> (Keywords+,
> Category+))) | (Category+,((Weight,Keywords+) |
> (Keywords+,Weight?))) | (
> Keywords+,((Category+,Weight?) | (Weight,Category+))))) |
> (Weight,((
> Identification,((Category+,Keywords+) |
> (Keywords+,Category+))) | (
> Category+,((Identification,Keywords+) |
> (Keywords+,Identification))) | (
> Keywords+,((Category+,Identification) |
> (Identification,Category+))))) | (
> Category+,((Weight,((Identification,Keywords+) | (Keywords+,
> Identification))) | (Identification,((Weight,Keywords+) |
> (Keywords+,
> Weight?))) | (Keywords+,((Identification,Weight?) | (Weight,
> Identification))))) |
> (Keywords+,((Identification,((Category+,Weight?) | (
> Weight,Category+))) | (Category+,((Identification,Weight?) |
> (Weight,
> Identification))) | (Weight,((Category+,Identification) | (
> Identification,Category+)))))) >
>
> Which looks pretty intimidating as far as a model goes.
>
> However, it is really pretty simple. You basically enumerate all the
> possible ways you could enter the data. Given a choice of 4 objects you get
> 4! ways = 24 pathways.
>
> From an authors point of view though, this is pretty simple - having chosen
> one of the 4 objects - then you must decide on one of the remaining 3
> objects to enter - having chosen that one - you then get to choose one the
> remaining two - and having chosen that one - the last one is given. The
> authoring interface is really quite slick.
>
> This is one time you don't want to concentrate on "optimization" of DTD
> code - you want to make the authoring straight forward.
>
> Generating this turned out to be pretty simple since I was using Near & Far
> Designer to build the model using a graphical interface. The biggest problem
> I had was avoiding ambiguities.
>
> Cheers...Hugh
> CyberSpace Industries 2000 Inc.
> XML Consulting and Training
>
> -----Original Message-----
> From: Dharmesh Shah [mailto:dharmesh@telocity.com]
> Sent: Thursday, November 22, 2001 10:45 PM
> To: Albena Georgieva; Xml-Dev (E-mail)
> Subject: RE: [xml-dev] How to avoid the sequens of child elements in
> DTD, yet keep the cardinality?
>
>
> Albena,
>
> When the order is not important you can do like this
> <!ELEMENT header (Identification | Weight | Category | Keyword )* >
>
> or
> <!ELEMENT header Identification, ( Weight | Category | Keyword )* >
>
> but in your case, since there restrictions on the no of occurrences you the
> order has to be specified. I don't think there is any other way out.
> <!ELEMENT header (Identification, Weight?, Category+, Keyword* )>
>
> Regards,
>
> Dharmesh
>
> -----Original Message-----
> From: Albena Georgieva [mailto:albena@info.nl]
> Sent: Wednesday, November 14, 2001 5:15 AM
> To: Xml-Dev (E-mail)
> Subject: [xml-dev] How to avoid the sequens of child elements in DTD,
> yet keep the cardinality?
>
>
> Hi there,
>
> I am creating a DTD document and I have difficulty to express
> that the element type Header:
>
> 1. must have one and only one child element of type Indentification
> 2. Can have [0 ... 1] Weight children elements
> 3. Must have at least one Category child element
> 4. Can have [0 ... n] Keywords
> 5. The order of the different children is not important
> 6. If there are several children of the same type, then they should be
> following each other
>
> Good example:
> <Header>
> <Keyword>Navratilova</Keyword>
> <Keyword>Tennis</Keyword>
> <Identification id="1111"/>
> <Category>Sports</Category>
> </Header>
> Another good example:
> <Header>
> <Category>Sports</Category>
> <Keyword>Navratilova</Keyword>
> <Keyword>Tennis</Keyword>
> <Identification id="1111"/>
> <Weight priority="3"/>
>
> </Header>
>
> Not accepted example
> <Header>
> <Category>Sports</Category>
> <Keyword>Navratilova</Keyword>
> <Identification id="1111"/>
> <Keyword>Tennis</Keyword>
> <Weight priority="3"/>
> </Header>
>
> I tried as follows:
>
> <!ELEMENT header (Identification| Weight? | Category+ | Keyword* )+>
> But then also this example becomes valid which is not what I am aiming to:
>
> <Header>
> <Category>Sports</Category>
> <Keyword>Navratilova</Keyword>
> <Keyword>Tennis</Keyword>
> <Identification id="1111"/>
> <Weight priority="3"/>
> <Category>Sports</Category>
> <Identification id="2222"/>
>
> </Header>
>
> And if I say so:
> <!ELEMENT header (Identification, Weight?, Category+, Keyword* )>
>
> It is better, but then we have to comply to the sequence of the children,
> which is what I want to avoid ...
> Any ideas, help please?
>
> I wish you all a very nice day!
> Greeting,
> Albena Georgieva
>
>
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