It seems like both Lorna and myself are not really paying attention to the
things being said here in Reston ;-)
I was wondering about the ordering thing, and don't understand why it is a
problem to implement a schema that doesn't have an ordering restriction.
If
you replace <xs:sequence> with <xs:choice>, doesn't that completely get
rid
of the restriction?
For example if you use:
<xs:element name="lom">
<xs:complexType>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element ref="general"/>
<xs:element ref="lifeCycle"/>
<xs:element ref="metaMetadata"/>
<xs:element ref="technical"/>
<xs:element ref="educational"/>
<xs:element ref="rights"/>
<xs:element ref="relation"/>
<xs:element ref="annotation"/>
<xs:element ref="classification"/>
</xs:choice>
</xs:complexType>
</xs:element>
that allows you to use the element in random order.
Best wishes from Reston,
Pierre Gorissen
p.s. temperature is 30 degrees Celsius over here :-)
----- Original Message -----
From: "Lorna M. Campbell" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 10, 2004 9:56 PM
Subject: Re: Implementing IEEE LOM Metadata
> Hi there,
>
> Thanks for all your work here guys! It may have been a wet weekend but
surely
> there are more fun things to do than playing with schema?!
>
> As usual I'm very cautious about commenting on issues relating to
bindings
so
> please feel free to ignore my input if it's unhelpful or if I'm way off
track....
>
> The issues of ordering is pretty contentious and I suspect that there is
no easy
> way to resolve this. I gather from Ben's comments and from other
implementers
> I've spoken to that it is simplest to create a binding that enforces
order.
> However this constrains the LOM conceptual data schema which does not
enforce
> ordering. By enforcing ordering you are effectively creating a profile
of
the
> original data schema.
>
> Having said all that, we clearly need a workable solution but I'm unsure
whether
> this is the right way to progress. Ben, Phil and others may remember
the
first
> CETIS CodeBash where we discovered that differences in the way systems
handled
> metadata frequently resulted in lack of interoperability. For example,
systems
> that expected ordered metadata sometimes could not import packages that
did not
> enforce ordering despite the fact that these packages were effectively
"valid".
>
> If we are going to create a basic binding that will be of maximum value
to
all
> UK LOM Core implementers it needs to be as generic as possible. I would
feel a
> bit uneasy if we constrained developers who build profiles based on the
UK
LOM
> Core by effectively requiring them to enfore ordering.
>
> I'd appreciate hearing the thoughts of those who know a lot more about
XML
> bindings than me!
>
> All the best
> Lorna
>
>
>
>
>
> All,
> I have looked at the existing IEEE XML Binding and have come to
> the conclusion that if we want a really simple schema that is easy to
> read and easy to process using castor/xerces etc that I would have to
> impose order on the models or develop another way of checking the use of
> elements that are only allowed zero or one times.
> I would go for the approach of using order but this does mean
> that if we validate externally produced LOM files they may fail because
> the IEEE LOM does not specify ordering.
> Does anybody have any opinions on this before I go ahead and
> finalise the first draft?
>
> Nothing like a wet Saturday for writing schemas :)
>
> Regards,
> Ben
>
> ---------------------------------
> Dr Ben Ryan
> --
> Lorna M. Campbell
> Assistant Director
> Centre for Educational Technology Interoperability Standards (CETIS)
> Centre for Academic Practice, University of Strathclyde
> +44 (0)141 548 3072
> http://www.cetis.ac.uk/
>
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