Re: [cellml-discussion] Include_in_CellML_1.2 requested: [TrackerItem153] Allow multiple connections between the same pair of components

[Jonathan Cooper]

* David Nickerson <[EMAIL PROTECTED]> [2007-08-29 04:21]:
> Andrew Miller wrote:
> >>>   * Implementation experience suggests that it is no harder to allow 
> >>> multiple
> >>> connections between the same pair of components when writing simulation
> >>> software, but the extra constraint imposes more work on developers when 
> >>> writing
> >>> tools which try to validate the model.
> >>> 
> >> This seems to be a good reason to keep the rule as it is. Given there is 
> >> already a sever lack of CellML validation tools it seems a bad idea to 
> >> be making it more difficult for people to write such tools.
> >>   
> > I don't follow. Removing the constraint should make life easier for 
> > validation tools - it is one less thing they have to check.
> 
> ok - guess I misinterpreted your comment. However, given the only tools 
> close to CellML validators currently available already implement this 
> check, it would appear that its not too much work to do so.

Indeed - it's a single assertion in Schematron, for instance, and I
wouldn't think it'd be much harder in any other framework.

Overall, I don't have a strong opinion either way on this issue.  Just
removing the assertion should allow my software to still work with the
change.  I do recall however that COR used to (and maybe still does)
restrict models to having only one group element for a given relationship
type, for ease of implementation.  So there could be concerns in some
quarters.

Jonathan.

-- 
Jonathan Cooper  MSN: [EMAIL PROTECTED]  www: jonc.me.uk/

Our library has so many books they had to put it in a multi-story building.
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Re: [cellml-discussion] Include_in_CellML_1.2 requested: [Tracker Item 153] Allow multiple connections between the same pair of components

[Matt]

Semantically I think this is fine and theoretically does not change
the meaning of connections.

It's important to highlight that software developers will need to:

1) relax the validation constraint for the existing rule (i.e. only
one connection between any two components)
2) understand that component_1 and component_2 of map_components can
change order over connection elements between the same components
(some software may have used the current notion of there being only
one connection and one order to component_1 and component_2 to
optimise in memory object references)

I think this could have some pronounced effects on some software.

I wouldn't mind reworking the connection syntax altogether ... but
that's another proposal.




On 8/29/07, Andrew Miller <[EMAIL PROTECTED]> wrote:
> Hi all,
>
> Are there any objections to marking this as something we should include
> in CellML 1.2?
>
> Best regards,
> Andrew
>
> [EMAIL PROTECTED] wrote:
> > Andrew Miller <[EMAIL PROTECTED]> has asked  for Include_in_CellML_1.2:
> > Tracker Item 153: Allow multiple connections between the same pair of
> > components
> > http://bowmore.elyt.com/bugzilla/show_bug.cgi?id=153
> >
> > --- Additional Comments from Andrew Miller <[EMAIL PROTECTED]>
> > Section 3.2.4 of CellML 1.1 states, in the second sentence of the second
> > paragraph: "Only one connection may be created between any given pair of
> > components in a model".
> >
> > This is a fairly pointless restriction from all fronts:
> >   * From a model authors perspective, it creates a burden on the author to
> > consolidate all their connections which may have been created for different
> > purposes, and current model authors claim that such consolidation is time
> > consuming and error prone.
> >   * From a model readability perspective, it is also burdensome because
> > connections between variables may not be in a logical order (this is less 
> > of an
> > issue if tools are used, but the point still holds).
> >   * Implementation experience suggests that it is no harder to allow 
> > multiple
> > connections between the same pair of components when writing simulation
> > software, but the extra constraint imposes more work on developers when 
> > writing
> > tools which try to validate the model.
> >
> > To fix this, we could simply drop the first two sentences of the second
> > paragraph of Section 3.2.4, and perhaps replace them with a short 
> > explanation.
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