25: Effect Activities used by the acquisition case

Before we inspect Activity IdentifyAcquireAttachPhysical in detail, it helps to inspect some of the 'effect' Activities used by the StateMachine Transitions shown in: 22: Mini StateMachines for @Entity, PotentialPhysicalAsset, ActualPhysicalAsset.

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The case of the 'effect' Activity DoManifest on the manifest() Transition to state Exists is interesting w.r.t. this Webel Best Practice policy:

Webel Best Practice: UML/SysML: If you have a Boolean "state flag" attribute corresponding to a State you MUST set it on an 'entry' of the State, not on the 'effect' of a Transition into the State (otherwise with multiple incoming Transitions it could be WET and breaks SSoT).

It represents in fact a «physical» PhysicalEntity becoming "real". At the time it reads itself the PhysicalEntity must still be in the state Phantom; by the end of the Activity in the real world it "exists" (and indeed now has mass), but the Boolean state flag isExists does not get set to 'true' until we hit the 'entry' Activity of the state Exists (which is a simple OpaqueExpression isExists=true).

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Screencast: The Webel Digital Twin Pattern for SysML: Part 1: Simulating acquisition or creation of physical assets using Activities and StateMachines in Cameo Simulation Toolkit.

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26: Activity IdentifyAcquireAttachPhysical

Notes

[POLICY]{STRICT} Webel Twin Pattern: A PotentialPhysicalAsset is «digital», not «physical». It is used to acquire (an existing) or create (build, manifest, make) an «physical» ActualPhysicalAsset, which is a special case of «physical» PhysicalEntity.

[POLICY] Webel Twin Pattern: Once a PotentialPhysicalAsset has been integrated with a real, existing (has mass) ActualPhysicalAsset under twinning control, its job is done forever (although it may be kept as an historical tracking record).

[POLICY]{STRICT} UML/SysML: If you have a Boolean "state flag" attribute corresponding to a State you MUST set it on an 'entry' of the State, not on the 'effect' of a Transition into the State (otherwise with multiple incoming Transitions it could be WET and breaks SSoT).

[MODELLING, TIP]{SUGGESTED} UML/SysML: A Boolean "state flag" attribute corresponding to a State can be useful for indicating states in some diagram types (but must be synchronised with Transitions to States carefully).

Snippets (quotes/extracts)

Traditionally, industry has created digital twins by retrospectively mapping, scanning, surveying, digitising or developing a digital copy of a real world object.

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