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Wednesday, February 10, 2010

Architecture or Design?

I mentioned the A word in my last post (Are there any System Analysts out there?). As regular readers might have noticed, I have over the years of this blog taken the odd pot-shot at Architects. But I’ve avoided direct comment on architect and architecture. Somehow it feels the time has come to address this debate.

I should say before we go too far that when I talk about Architecture I’m thinking software architecture. And when I talk about Architects I’m thinking about the architecture of software. I’m not thinking of network architecture, or business architecture, of course these topics are connected with software architecture but we need to narrow the topic down a little.

Nor am I talking about system architecture and system architects. System architecture is a particularly confusing concept because we first have to define the size and scope of our system: a piece of software is a system, so too is the computer it runs on and so too is the combination of both. So lets agree to leave system architecture to one side too.

Before we can tackle to subject of Architects I think we need to get a better understanding of architecture. So I’ll defer architects to another day and think about the nature of architecture today.

If we look up architecture in the dictionary then we find its all about design. Architecture is design. The word “architecture” (like the word “design”) is both a noun and a verb. Architecture is something you do (we may create a proposed architecture) and it is something you have, you software has an architecture whether it was design or not.

As an experiment, whenever you hear someone talking of “software architecture” mentally substitute the words “software design”. I don’t think you’ll find any loss of meaning.

Both design and architecture are, certainly in software systems and frequently elsewhere, part a deliberate attempt to create a particular outcome, they are also part emergent. How much is deliberate and how much emergent varies. As a result, the architecture (design) we finish with is something different to that which was planned.


(As an aside, we’ll talk about another time, that diagram is based on one from one of my favourite books, The Rise and Fall of Strategic Planning. There are close parallels to the way we relate to, and go about creating software architecture and business strategy.)

So architecture is design. Is it anything else? Anything more?

Architecture is more than design because the word architecture implies something bigger. An architecture is more than a design. You architect buildings but you design tents. Some of this “architecture as grand design” is just that, aggrandisement. It an attempt to make design into something grander. Personally I think design is a worthy and grand thing itself, you don’t need to aggrandise it any more.

In a software context there is the question of inside and outside. The term “software design” is often used to describe the external properties of the software, how it looks, feels, perhaps the features it offers. While
architecture often refers to the inside: how the thing hangs together and work. So there are “user interaction designers” but I’ve never heard of a “user interaction architect”.

I have long argued that software design exists in every line of code. Writing code is designing software. Certainly this fits with the “architecture is the inside” line of thinking but it doesn’t fit with so well with “architecture as bigger”. Somehow, while I happily argue that the choice between a FOR-loop and a WHILE-loop is an act of design, it seems wrong to argue that this is an act of architecture. But, according to own logic, that is what I am arguing.

The architect Ludwig Mies van der Rohe is reported to have said: “God is in the detail”. He wasn’t the first to use this quote but it does summarise his approach to architecture. He was an architect who was concerned about details. There was no lower bound for his architecture. So on that basis, Yes, whether you use a FOR-loop or a WHILE-loop, a bunch of IF-statements or a CASE-statement, you are making architectural decisions.

Architecture is design, it scopes up to the very big but it also includes the small details, because you just don’t know when the small details are going to become important.

2 comments:

  1. Hi Allan,

    An entertaining blog post as usual. The reason you can't find a link to the architect van der Rohe is that you didn't spell his name right! Here is the link you're after: http://thinkexist.com/quotation/god_is_in_the_details/213371.html

    And actually, van der Rohe quipped that "God is in the details", not the Devil. That was by Rickover, extending a German folk saying (see http://thinkexist.com/quotation/the_devil_is_in_the/175423.html and http://thinkexist.com/quotation/the_devil_is_in_the_details-and_everything_we_do/179813.html).

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  2. Thanks for the correction. As a general policy I don't update my entries after but this time I'll make an exception and fix it.

    (When I'm drafting an entry I often put [link] in to remind myself to find a link, that is the second entry in a row which I've missed one.)

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