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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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• MODAF Metamodel (M3)

Improving Consistency for Tools - ‘TRAK. Implementation. Architecture Description Elements’ Document

There is a constant need to reduce the scope for inconsistency in any architecture description. TRAK is no different. TRAK has been defined in a way that is free of implementation and using natural language wherever possible. One of the pitfalls of this is the possibility that names will be implemented inconsistently in tools. For example, the attribute ‘start date’ might be called ‘start date’, ‘start_date’, ‘startDate’, ‘Start Date’ and so on. The danger in this is that upon exchange the receiving tool might not recognise this if it is using, say, ‘startDate’.

I’ve therefore created a document titled ‘TRAK. Implementation. Architecture Description Elements’. To put it into context a couple of diagrams (produced using the OmniGraffle stencil for TRAK):

The TRAK. Implementation. Architecture Description Elements Document is Part of the set of Documents that Improves Consistency of Exchange of an Architecture Description

The TRAK. Implementation. Architecture Description Elements Document Responds to the Logical Definition of the TRAK Metamodel

The document is at https://sourceforge.net/projects/trak/files/Implement%20TRAK/

The purpose of this document is therefore to standardise the naming of the architecture description elements used in any implementation of TRAK, whether graphical or text-based.

In addition to naming this document also specifies the formats used for attributes such as text, language labels, geographic location and uniform resource identifier. It also identifies the allowed values where an enumerated list specified for an attribute.

None of this guarantees successful exchange - in a UML modelling tool there will be an extra wrapping applied through XMI which might be at a different version in the sending and receiving tool and in addition even if an element has the same name it might mean something completely different in each. This document is therefore one part of a set of normative measures needed to maximise the chances of successful interoperability between a pair of tools.

There are a couple of things still left to do, not the least of which is figure out how to specify privacy marking / security descriptor schemes. If anyone knows of any good standards-like sources for these please let me know.

Any constructive comments via the Sourceforge Tracker set up for implementation of TRAK at https://sourceforge.net/tracker/?group_id=393432&atid=2376222

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Forums

• See discussion thread in forums

External Links

• OmniGraffle Stencil for TRAK
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New Revision (“The ISO 42010 Mix”) of TRAK Released

Just managed to shovel the last part of the documents that defines TRAK into cyberspace last night. The main purpose of the revision is to anticipate the likely requirements from ISO/IEC 42010 expected to be released under a slightly new name during 2011. There are quite a few changes to the ISO not the least of which is that it has requirements for architecture frameworks and makes reference to a framework metamodel. The opportunity has also been used to respond to constructive comments and requests made by the INCOSE UK Architecture Working Group.

In the end this has proved a bigger change to the existing documents than anticipated. We now have a 3 document set that defines TRAK since it became clear that things that were global or common or which were best dealt with as “a whole” would be best separated into an overall TRAK Enterprise Architecture Framework document. This has meant things like the bye laws, colour rules and conformance/non-conformance with TRAK being moved into this document. It also provides the better place to provide advice on choosing an architecture description language to represent TRAK and to describe how TRAK relates to ISO/IEC 42010.

This new 3 document structure has resulted in breaking out a new project on Sourceforge. The top-level reference for TRAK is now trak.sourceforge.io which is an improvement on the old bifurcated reference to both the viewpoints (trakviewpoints.sourceforge.io) and metamodel (trakmetamodel.sourceforge.io) projects / sites. Errors or feature requests for any of the documents can be made on the respective site.

As a result of comments made by Rich Hilliard (always useful) it became clear that the old viewpoint definitions needed to be sharpened up. In particular I’ve added stakeholders derived from the standard , added more detail and examples to the presentation sections. Some of this existed in the old days before release as open source but never got incorporated into the new documents. In any case some of the thinking and the changes to the ISO have changed the content and it had to be started afresh. A suggestion was to add a ‘well-formedness’ section which attempts to define the minimum acceptable content for a view of each type. The latter was quite hard work and an empirical task as you think you’ve got it nailed, draw an example to immediately find that it breaks the rules. It’s not quite complete but a lot better for the effort and therefore worth releasing rather than waiting for perfection.

No doubt there will be a few “after shocks” but nothing of the scale of this revision (I hope!).

One of the ongoing questions is how to make it more concise, less wordy but accessible and understandable to the ‘normal’ Mk1 Human Being (the “non-softie”). In particular is there a way to define the minimum content visually without words - there are ways from the software world but are these likely to understandable to the non-softie or non-tecchie? Constructive suggestions on a postcard.

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