Monday, June 20, 2011

A Taoist Definition of Software Architecture

The question that I am asked most often in job interviews is “What is a Software Architect?” I am never sure whether I am being asked this question so that the interviewer can compare my answer with their own understanding of the role, or because they don’t really have a clue and would like someone to explain it to them. I assume the former, though I have sometimes suspected the latter. Since I have had to answer this question so often, one would imagine that I have cogitated a suitable job-winning answer. One would imagine rightly (though it has not always won me the job). 

So what is a Software Architect then? Here are some possible definitions:

  • A Senior Senior Software Engineer.
  • A Software Engineer who can reconcile the business and technical requirements of a complex software system.
  • A Software Engineer who manages a team and owns a budget i.e. knows how to drive Microsoft Project.
  • An accomplished Software Engineer who has grown weary of writing code (Oh, say it isn’t so!).
  • A Software Engineer with an IASA, TOGAF, FEAC or similar certification.
  • A Senior Software Engineer who has a SOLID GRASP of reading-edge TLA’s including OOP, SOA, AOP, UML, ALM, BDD, DDD, TDD and RUP.

Though there is some truth, and obviously a little humour, in the above definitions, I don’t think any of them hit the mark. Note that all of the above definitions contain the words “Software Engineer”; I believe strongly that Software Architects should be accomplished Software Engineers.

In my humble opinion the key attribute that differentiates the Software Architect from the Senior Software Engineer is the number of contexts that they take into consideration when designing software solutions and the processes to deliver and operate that software.

Or if you prefer a more Taoist definition:

Software Architecture is the process of designing and developing software in such a way that it will remain in harmony with the significant contexts within which it is created and runs over its entire lifetime.

Typically, when software is designed the contexts that are considered are the functional and non-functional requirements, and the financial and schedule constraints. The requirements are captured either upfront or over the course of the development process in a list of feature narratives, use cases, user stories, epics, diagrams or formal specification language artefacts; and typically only reflect the Technical and Business [Process] Contexts of the system.

The Financial Context is often expressed in the contract or project plan and is limited to an estimate of the software development cost and duration, an estimate of the infrastructure cost, and an, often limited, estimate of the operational cost of the system.

I say “limited” because the financial model often does not include how the operational, maintenance and support costs will change over the lifetime of the software. This includes how skills, and demand for resources with those skills, will change over time, e.g. Microsoft solutions that used C++ and COM half a decade ago, in the belief that .Net was a passing fad, or could not deliver the required performance, are having a hard time finding skilled developers with domain expertise to maintain and extend their code. Available skilled resources with C++ and COM skills are getting very expensive.

Outside of operating system and game development C++ is fast becoming the “new” COBOL, or more precisely what COBOL was at the turn of the century. That said, in light of some recent speculation about Windows 8 development, C# might be about to become the new C++, but I digress.

As an[other] aside, many requirements that typically make it into the non-functional category, including performance, scalability, security, privacy, maintainability, etc., clearly belong in the functional category because they all require architecture in the small; i.e you have to code for them at the lowest level; you can’t successfully bolt them on later. I am not sure I even believe in non-functional requirements anymore; if it is non-functional then it is not a requirement at all.

The context outlined above is already a lot of context. Surely given all this, one can design and develop usable, high quality software, that meets the clients requirements? Perhaps, with a little bit of luck and a team of stars; but given that the number of software development projects that still fail despite taking all this context into consideration (and all the advances that have been made in software development practices, processes, tools and technology), the odds are stacked against a successful outcome. So what contexts are not being considered that could turn failure into success?

I posit that it is the Human Context; or more accurately, the Social, Political and Cultural contexts in which the software has to exist. It is these often ignored contexts, that I actually believe are the most important; they should subsume all other thinking about how the software should be designed and developed.

Let me summarise and describe the contexts that  I believe should be considered when designing software (in priority order).

The Social Context

Software is ultimately about improving people’s lives. One should always know whose lives are going to be affected by the software, and how. This also includes how the development of the software is going to affect people’s lives. This aspect is often overlooked, even by the most enlightened software architects; the software industry is infamous for eating its own young in an effort to deliver on time, on budget, to spec.

This also goes way beyond usability, user acceptance, and project governance. This is a “people first” approach to software design and development, from the people who develop the software and the various stakeholders, to the end users, and everyone in between.

The Political Context 

How often is it that a project fails because its executive sponsor is either promoted, moves to another division, or leaves the company? Was the project initiated to primarily further the political aims of the sponsor or the corporate cabal of which she is a member? What happens if and when the executive sponsor achieves her actual goal, or looses her influence or position to a rival? Are there any stakeholders that have a vested political interest in a project failing? It may turn out that the client/customer is optimizing for a political outcome rather than the successful delivery of the solution. If this is the case one should modify ones architecture and execution plan to support their goal (assuming of course that it is not morally reprehensible!).

I have observed this enough that I now endeavour to ascertain the often subtle and hidden political driving forces on a project, and factor those into the design, development, and operation of the software. It always helps to optimize for the same thing that the [actual] client/customer is optimizing for.

Note that this is technically a sub-context of the Social Context above, but is important enough that it should be considered as a context in its own right.

The Cultural Context

This is best illustrated by an anecdote. In the late 90s I was a Development Consultant on a massive web portal project for a European telecommunications company. Despite the system’s complexity and the available budget, the project was poorly managed and there was no significant architecture for the system, and as a result the project was haemorrhaging cash. I could not understand why the client was allowing this to happen, until the executive sponsor took me aside and explained it to me; what they really required was the appearance that they were going to be first to market with a new technology. The quality of the solution, and its longevity, were mostly irrelevant. In the culture that the solution was being developed and deployed, it was the perception that was most important, not the actual product itself. Once I understood this I could optimize appropriately.

I have worked on software projects in Africa, Europe, North and South America, Australia and Asia and I have come to recognize the significant role that culture plays in the success or failure of a project. Ignore it at your own peril!

Note again that this is technically a sub-context of the Social Context above, but is important enough that it should be considered as a context in its own right.

The Financial Context

This is often a context that gets a lot of consideration, but as I have already alluded to above, it should cover the entire lifetime of the software.

The Business Context

This context represents the superset of Business Requirements. Nothing new here, but I continue to be amazed at how hard it is to extract the Business Requirements from stakeholders, regardless of whether waterfall or agile practices are being used.

The Technical Context

The usual suspects; Applications, Data and Technical Architectures (TOGAF) and the requirements they address.

Do note my comment above about functional versus non-functional requirements. 

A good software architecture will take all of the above into account. Obviously there is the risk of information overload. The number of contexts and the contents of each that need to be considered can quickly become overwhelming, and it can be very hard to filter the noise from the data. It is also easy to run out of time by fixating on a single sub-context, e.g. the minutia of the technical requirements (my favourite). That is not an argument for ignoring any particular context; it just means that one needs to have a formal process for comparing and prioritizing elements from different contexts. I will describe the process that I use in a later post.

To keep in line with the current trend in naming software development methodologies and practices I have named the approach described above Gestalt-Driven Development”. I plan to elaborate on GDD in future posts.


  1. I'm reasonably certain that i've never worked with an architect that was even cognizant that your first three contexts actually existed let alone factor them into their ideals for the project underway. I'm happy enough when the business context is actually considered and utilized or the technical context is taken beyond the simple thought of what cool technology should we play in now?

  2. Good architects use various software architectural models that specialize in communicating architecture. I do look forward to read your interesting posts in the future. Good share!

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