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Add a new Element type 'Activity' to the Strategy Layer

I suggest a new Element type ‘Activity’ could be useful in the Strategy (Strategic) Layer, providing for more flexible behaviour modelling within strategic (conceptual) architecture.

Currently the Strategy Layer contains 3 forms of behaviour:

  • Course of Action: which I argue shouldn’t be there (see Issue #98).
  • Capability: which is not a behaviour at all (see Issue #96).
  • Value Stream (VS): which is a model of behaviour, as a collection of Value Stream Stages (VSS).

A Value Stream (VS) is usually considered to be a collection of Activities, showing how value is created for a stakeholder through a series of Stages (VSS). The VS and the VSS can be modelled in ArchiMate but not the Activities. We are obliged to use VS as a surrogate for Activity, but this isn’t entirely satisfactory since a particular Activity might be used in several VS.

Activity is used by many models and frameworks outside ArchiMate as a generic name for any sort of behaviour. The granularity of Activity is typically and deliberately unspecified, but in general it is used to represent behaviour in models of strategic or conceptual architecture. Examples are:

  • Porter’s Value Chain uses the word Activity to describe behaviours in each of its activity groupings, each of which is essentially a Value Stream; i.e. a Value Stream in Porter’s model is a collection of Activities.
  • Osterwalder’s Business Model Canvas has Key Activities (KA) as one its 9 ‘Building Blocks’.
  • Checkland’s Soft Systems Methodology describes a Business Activity Model (BAM) as a model of an enterprise system, from the perspective of a stakeholder.
  • IT4IT refers to ‘supporting activities’ along its Value Chain.

I think having an Activity concept would make the Strategy Layer ‘look and feel’ more like the other Layers; at the moment the metamodel looks oddly distinct. For example:

  • It should be possible to associate an Activity with one or more Value Streams, so a Value Stream would be an aggregation of Activities.
  • A Capability, as a Composite, should be assignable to an Activity or an Activity would be aggregated to it. Capability makes no sense unless linked to performing some kind of behaviour.
  • If this concept were to be admitted, it would mean sub-classing Resource into Active and Passive, since Activity would access Passive Resource and Active Resource would be assigned to it. I don’t think this would be a bad thing; e.g. OMG's BACM makes this distinction at the strategic level.