[glue-wg] Placeholder for IDs?

[stephen.burke at stfc.ac.uk]

David Horat [mailto:david.horat at cern.ch] said:
> In my opinion, there should not exist any placeholder for Foreign
Keys. If a FK is mandatory, you need to publish it. If not, just make
them optional. If you put a placeholder in a FK, then the word mandatory
has no real meaning.

It's really the other way around, if an attribute is mandatory you have
to publish *something*, even if for some reason the info provider is
unable to determine the correct value. In the particular case I
encountered (Policy -> UserDomain) I think it is a mistake for it to be
mandatory, but there are other cases, e.g. ToComputingService ->
ComputingService, where it clearly is correct for it to be mandatory but
nevertheless the info provider may for some reason fail to determine the
correct ID. You then want a value which is clearly erroneous so you can
detect the failure.

  Also for example the way the gip works is to have a template file,
with values which should be changed by the dynamic provider. If that
provider fails the values in the template will become visible, and again
you want to use something which is easily detectable.

Stephen
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