[PLCS] Some model issues arising from DEX capabilities work

["Ian Bailey" <ian.bailey@eurostep.com>]

Title: Message

Hi Folks,

 

I've been working on some of the property capabilities, and a couple of issues have arisen with resource properties.

 

The first, and simplest to fix is that is not possible to assign a person and organization to a resource_property - the entity is missing from person org select in the longform ARM schema. As I say, this should be pretty easy to fix.

 

The second is more debatable and rather more complex. For required resources we sometimes have required properties (see example in the assigning_required_resources capability with the test equipment with a required accuracy). For every other case in PLCS we assign requirements when we want to have required properties - i.e. we create instances of requirement_assignment, requirement, requirement_version, etc. Requirement is a subtype of product because there is a need to configuration control requirements. In the case of required resources however, we cannot do this as the requirement_assignment select does not have required_resource_by_resource_item in it.

 

Hence I have just shown properties being assigned in this capability. However, I am not comfortable with this, as those properties will be requirements and will effectively slip through the configuration control net. It also provides endless possibilities for data inconsistency through the product lifecycle. For example, imagine a system requirements document that defines supportability requirements - one of which is an inspection ramp that can lift a 2 tonne road vehicle. This would be modelled as a system_element (qualified as "required" and e.g. assembled into a system breakdown called "support solution"). However, when we get into the support phase, the required_resource_by_resource_item isntance will be used to duplicate the same information originally defined in the requirements.

 

My recommendation is to go for a consistent approach, where requirement, requirement_version, etc. are always used to represent required properties - chances are these properties originated in a requirements management tool, anyway. But, to do this we need a change to the model to extend the requirement_assignment select to inclide required_resource_by_resource_item (and any other resource entities the PLCS modellers deem fit to include).

 

Regards
--
Ian Bailey
Eurostep Limited - www.eurostep.com
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