HISTORICAL: On using the plain ol' UML InformationFlow in SysML (but please instead use a SysML ItemFlow without an 'itemProperty' on Associations)

In the early days of SysMLv1, which builds on UML2, this slide was of interest. It is marked for replacement with one that simply shows the SysMLv1 way. But you can learn plenty from it, suggest you don't skip it.

UML has a basic system for indicating flows of types of information at a high level of abstraction. This slide is here solely for historical purposes to show where the preferred SysML ItemFlow comes from.

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In this example, an Association named A-B between blocks A and B actually has a UML InformationFlow (not a SysML ItemFlow) with a 'conveyed' Classifier Data, which happens to be a SysML ValueType.

The model for the diagram here has been "fudged" to use InformationFlow only

In the structure compartment of block Context a specific connection has been made between the anonymous part properties :A and :B (typed by blocks A and B). The anonymous Connector :A-B is typed by Association A-B. A compatible InformationFlow with conveyed classifier SpecificData has been applied to the Connector, where SpecificData is a specialisation of Data.

Beware that:

The UML InformationFlow notation and the SysML ItemFlow notation can sometimes clash with the notation of named Associations and named and typed Connectors

The reality is that, while the UML InformationFlow is formally still supported in SysML, you are "supposed" to use a SysML ItemFlow (which extends InformationFlow), because it has some extra constraints for use with FlowProperty on blocks. And the MagicDraw/Cameo tool in fact guides you to do this:

In MagicDraw SysML or Cameo Systems Modeler if you drag a Classifier onto an Association or Connector, it will in fact create a SysML ItemFlow not a UML InformationFlow

The concepts UML InformationFlow and SysML ItemFlow sometimes get conflated:

SysMLv1: An ItemFlow without an assigned 'itemProperty' is sometimes informally/casually referred to as an "information flow", especially when applied to an Association (because it is much like a UML InformationFlow), but formally it is a SysML ItemFlow.

We see next how to use a SysML ItemFlow on an Association.

ASIDE: If you try to reproduce this diagram (best not to) you may encounter this strange bug:

MagicDraw UML/SysML/Cameo 19SP3: Sometimes on application of a named Association as the Type of a Connector that already has an InformationFlow (or ItemFlow) applied, the direction of the InformationFlow (or ItemFlow) indicator swaps.

The diagram here is actually HACKED to show how it is supposed to work.

Up next

Using SysML ItemFlow on an Association to show compatibility with a physical flow

Notes

[ISSUE, TOOL] MagicDraw UML/SysML/Cameo 19SP3: Sometimes on application of a named Association as the Type of a Connector that already has an InformationFlow (or ItemFlow) applied, the direction of the InformationFlow (or ItemFlow) indicator swaps.

[DISPLAY, NAMING, WARNING] The UML InformationFlow notation and the SysML ItemFlow notation can sometimes clash with the notation of named Associations and named and typed Connectors