What is "Architecture"? It's not "Design"!

Put five IBM Architects in a room, ask that question, and stand back...  And, if the energy levels sag, ask the supplemental “what’s the difference between architecture and design?”

From the myriad of arguments that ensue, I see two common themes:

1.      “Architecture is the big picture stuff, design is the detail”

2.      “Architecture provides the guidance and governance to ensure good design”

Of course both ideas are critical – the first suggesting mechanisms for breaking large systems down into manageable chunks (“systems of systems” etc), while the second offers, at any scale, a sense of “that architecture would be a good basis for that design”.  

But I, for one, do not like homonyms (the same word meaning different things to different people); and therefore find such conflicting distinctions tiresome.  So, for many, many years, and based on my aero-engine days(*), I have been an advocate of definition #2, arguing that the complementary but fundamentally different ideas of architecture and design are scale free:  for example

·         there are “few” chip architectures underpinning many chip designs,

·         there’s “some” network architectures (SNA(!), TCP/IP) that form the basis of 1000’s of network designs

·         and (maybe my favourite), there are (were!) exactly five Gartner client-server architectures (“distributed presentation”, “remote presentation”, “distributed logic”, “remote data access” and “distributed database”) selected from over and over again – Cloud, anyone?

Maybe the best distinction between the two for me is… bridges – how many bridge architectures are there?  Wiki says seven.  But how many bridge designs are there?  Exactly the same number as “how many bridges are there?”!  The critical question therefore is – how do you chose the right bridge architecture for your specific(sic!) design?  It’s all a question of context…

PS:  (*)Aero-engine architectures:  for example, there are (or have been!) pros and cons to “two shaft versus three shaft; or “high bypass turbo fan versus turbo-jet”, or “reheat versus no reheat”…  Every engine design needs to choose between these architectural options.