Agilist strike again

Continuing on my critique of research in agile methods, started with this (relatively) popular post on integrated concurrent engineering compared to agile software methods.,.

I ran across this post by Dean Leffingwell and this post by Chad Holdorff, extolling the "proper" mixture of component vs. feature teams (definitions included in these posts, somewhat) on a project.  Problem with this post is that there are not studies showing correlation with the two variables on the graph from Dean, the proposed mixture of component and feature teams, and the productivity and/or quality of output of the teams that do and do not follow this proposal.  Additionally, there is no notion of context: why types of systems does this model work for? where does it break down? At best, this mixture is simply a hypothesis that needs to be tested through proper study.  They should be marked with "notional" and for illustrative purposes only (i.e., they are fiction).

Now compare the notional mixture of structuring teams with the work of using tools like Design Structure Matrix to organize and improve global product development.  A good starting point would be Steve Eppinger's paper, A Model-Based Method for Organizing Tasks in Product Development.  Here we have a model, formalized, that has been applied and the outcome studied for productivity changes.  There are other, dare I say, mature ways to manage dependencies.

The agile crowd needs to move past heuristics and case studies, and no notion of context, to describe what works and what doesn't work.  Further, the definition of work needs include a notion of output quality (and not just absence of defects).  There is are better ways than the simple heuristics and one off case studies.

System Architecture Principle 8: Beware of software

Tagline: Beware of software.

Descriptive version: Software grows very complicated very quickly.  It can be of high leverage, but can be potentially dangerous because of how complicated it can become.  Further, software does not have a "laws of physics" like physical systems making it difficult to reason about using models and such (the code is the model!).

Prescriptive version: When deciding to allocate functions to software, be aware that you are substantially increasing the internal complexity and number of operating modes of your system.

Discussion: I am not sure if this is an architecture principle, yet.  I am certain it will be one with enough time.  Certainly of my principles it is the one that has the shortest lifespan. 

Software is this very new thing that can quickly grow substantially more complicated than the physical system in which it operates.  The number of operating modes of software is estimated as the number of inputs times the number of outputs to some power (Ayaswal2007).  Further, software seems to be having a tendency to creep from being something embedded in some component helping that component deliver its functions to an item that becomes a system bus interacting with just about every component in the system.  On top of all of this, the work of software is largely hidden in complicated code in bits on software developer's computers making it even harder to reason about.

Citation
B. K. Ayaswal and P. C. Patton. Design for Trustworthy Software. Prentice Hall, 2007.

System Architecture Principle 7: You can't escape the laws of physics

Tagline: You can't escape the laws of physics (Augustine1996).

Descriptive version: No amount of being clever will allow your system to violate the laws of physics.

Prescriptive version: You can't change the laws of physics; use them, obey them, but don't think for a moment that as an engineer or architect that you can escape them. 

Discussion: This is one of the principles which reflects my background, with my undergraduate degree being in physics.  I spent the better part of five years (I started in graduate school and decided it was not for me at the time) studying how the universe worked, the models that explained why things happened all around us.  As you know, this attempt to understand the universe is very much related to engineering, but in some ways very different than engineering.  Engineering seems to be more about, given the set of laws that govern the workings of the universe, how can we (engineers) leverage them to affect the world around us.  It is very tempting to confuse this ability to "engineer" the world with the ability to "engineer" the laws of physics.  Falling into this confusion would likely lead to very undesirable consequences.

Citation
N. R. Augustine. 1996 Woodru ff Distinguished Lecture Transcript. http://sunnyday.mit.edu/16.355/Augustine.htm, 1996. section title Conceptual Brilliance Doesnt Blind the Laws of Physics.

System Architecture Principle 6: System design drives life cycle costs

Tagline: System design drives life cycle costs (Blanchard2011) (Crawley2010).

Descriptive version: The systems architecture, and hence the work of the architect, has the largest impact on system life cycle costs.

Prescriptive version: The work of the system architect can drive significant changes in the excepted life cycle costs of the end product.  It is important for the architect to understand the life cycle costs constraints (based on perceived value of the acquiring organization and the desired financial margins of the supplying organization) and to make sure the system architecture supports fits within the targets.

Discussion: The principle is support by the notion that highest management leverage is at the very beginning of the project, when the least amount of money has been committed to the project.  That is, the very first steps, deciding on the system architecture, is the biggest opportunity to steer a project to a desired life cycle costs.

Citations
B. S. Blanchard and W. J. Fabrycky. Systems Engineering and Analysis. Prentice Hall, 2011.

E. Crawley. Esd.34 lecture 1, September 2010.