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[cellml-discussion] CellML Versioning Strategy


Chronological Thread 
  • From: ak.miller at auckland.ac.nz (Andrew Miller)
  • Subject: [cellml-discussion] CellML Versioning Strategy
  • Date: Wed, 19 Sep 2007 15:27:58 +1200

Matt Halstead wrote:
> "Andrew was opposed to the idea of changing all the namespaces, and
> suggested changing the namespace of a particular element in only some
> circumstances:"
>
> I agree very strongly with this. It would make writing out xpath
> expressions simpler since you know absolutely what namespace for what
> elements you want to target.
>
> The namespace argument also applies to new attributes - they need to
> be placed into a new namespace too and references explicitly as such
> in a document since the rule for CellML is that unnamespaced
> attributes will acquire the namespace of the element owning them.
>

This is something which I think we should change ASAP - it is a
deviation from the XML specification which we should not be declaring at
the CellML level. I think that once this is sorted out, versioning the
elements is sufficient, and there is no need to mix namespaces of
attributes within the same element (if the attribute definitions change,
then the semantics of the element have changed, so we change its namespace).

>
> "Poul thinks that mixing namespaces means you have to scan the entire
> document before you can determine that you don't support a particular
> version of the model. "
>
> I don't understand that. You might want to scan a document to see what
> "versions" the model conforms up to, but one of the nice things about
> pushing these new elements/attributes into new namespaces is that you
> can still treat a model as say 1.1 even if it contains 1.2 elements
> and attributes. So the "scanning" is already done implicitly by a
> library that is simply trying to use a CellML model and is reading it
> at the version level it is capable of.
>
> Of course CellML 1.1 is broken in this sense.
>
> "There was some discussion about what namespace the model element
> should be in CellML 1.2. Randall suggested it should be in CellML 1.1
> and not CellML 1.0 "
>
> Can we apply this to all existing elements and attributes then? So
> that when 1.2 comes along and its interpretation we only really have
> 1.2 and 1.1 to deal with.
>
I think that was the intention - model was only an example of an element
with semantics that we don't plan to change, and any other element which
is neither new nor changed in CellML 1.2 would be treated along the same
lines. Then we can just implement 1.2 (and perhaps 1.0) without worrying
about explicitly implementing 1.1 as a separate task.

Best regards,
Andrew

> cheers
> Matt
>
>
>
> On 9/19/07, Andrew Miller <ak.miller at auckland.ac.nz> wrote:
>
>> Hi all,
>>
>> At the break-away session on the versioning strategy for CellML (which
>> followed the Auckland CellML meeting today) we discussed the future of
>> how we would version CellML, including whether we would put all elements
>> for the next version of CellML in a completely different namespace, or
>> only the elements that had changed.
>>
>> A summary of the discussion is up at
>> http://www.cellml.org/meeting_minutes/MeetingMinutes19September2007/
>> under "Breakaway session on versioning strategy for CellML". Note that
>> the participants at the session have not had a chance to correct errors
>> in it yet, and it may not yet accurately reflect everyone's view.
>> However, it does lay out the options, and so may provide a starting
>> point for any suggestions or comments from the community.
>>
>> Please send and such suggestions or comments to the CellML discussion
>> mailing list prior to the 3rd October 2007.
>>
>> Best regards,
>> Andrew
>>
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>>
>>
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