A MODAF Architecture Description Only Applies to a ‘System of Systems’?

In the MODAF metamodel (M3) v 1.2.004 we have:

ArchitecturalDescription : public <<stereotype>> class

A specification of a system of systems at a technical level which also provides the business context for the system of systems.

This definition of an architecture description has been unchanged since at least v 1.1 (May 2007).

This defines an AD as a specification. This is too restrictive and doesn’t fit current usage within the MoD since MODAF ADs are more often used to discover and analyse the architecture that exists in order to assess the impact of decisions or proposed design changes.

The real problem is the ‘system of systems’ bit because it looks to be misusing the term. In restricting an AD to a ‘system of systems’ and not ‘system’:

 
• Are they then saying it is only an AD when it describes a ‘system of systems’? Since a ‘system of systems’ is formed from systems that have an independent existance this definition means that you can’t have a MODAF AD of a submarine where the systems are tightly coupled and have no meaningful existence away from the submarine.
 
• Are they saying MODAF cannot be used to describe a vanilla system? This states that a description of the architecture of a system (formed from essential parts that aren’t themselves systems) isn’t an AD.
 
• Are they saying that ‘system of systems’ is a new type (in which case how do they know it can be described using MODAF)? This would be technically incorrect since a ‘system of systems’ is of the type ‘system’ with the emergence et al that this brings.

I don’t for one minute believe that any of this is the intent nor that this represents how MODAF ADs are intended to be used. It doesn’t therefore reflect the real use of an AD and needs to be changed to make it a valid definition.

The good thing is that the MODAF M3 recognises the distinction between the architecture (of the system) and the thing that describes it (the AD). Far too many others confuse the 2 concepts

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External Links

• MODAF Metamodel (M3)