Why simplicity starts with design

Four top tips

Build a business case: developing custom apps

I was talking with a fellow IT professional recently who was saying that you should "program simply" but "design with complexity". I do understand the point that he was trying to make - that is, during the design stage take into account the problems in your domain so that these have been worked out as much as possible before the coding starts.

In many ways this is sound advice as otherwise a solution may be proposed that is inappropriate, inefficient or impossible to implement. However, if this is taken to the extreme, then the design may take on the importance of the final deliverable in the minds of the designers. It may also become complex enough to be worthless!

Last time time I argued to "Keep it Simple Stupid", or KISS, with regard to software implementation. However, it is not just the software that needs to maintain its simplicity - it is also the design. That is not to say the design will be simplistic but rather that it should be as simple as it can be in order to fulfill its requirements.

This in itself sounds straight forward, but consider what I have said here: that the design should be "as simple as it can be in order to fulfill its requirements" - that is a slightly odd phrase. What I am trying to get at is that the design should be no more complex than is needed to help to understand how the software will need to be constructed.

This differs from the requirements of the software itself. Remember, a design is an abstraction of the software that will be written - it is not the software itself. At the end of the day, it should not be as complex as that software - it's a simplified representation of it.

Clear models in any Java-oriented design process, modeling is a key element. An overly complex model may actually be less useful than a simple model anyway. Why? Because a complex model, with a large number of classes, objects, relationships and use cases may actually obscure the meaning originally intended. Worse, the density of elements in the model may actually mean that developers get "model overload" and switch off.

If this happens, then the formal model may be forgotten and developers will work from their own interpretation of the requirements. This may result in the production of an implicit design, which is no more than a set of mental models.

So, how can simplicity in design be achieved? Here are some practices that I believe can help:

Don't try to test designs

As I have said above, a design is an abstraction of the software to be implemented. As such it is not possible to test a design to check its completeness, its suitability or to validate its functionality. So we should not attempt to do so. If we need to validate part of a design then prototypes can be built. If we need to explore some complex concept then a proof-of-concept implementation can be created. We should not pretend that a design is something that can ever be as all encompassing or complete as the resulting software. Instead the test should be: "Is it fit for purpose?" If it passes this test, then it has met its goals.

Use the simplest tools

Tools are another area in modeling that people get hung up on. Some modeling tools tend to promote the creation of large complex models - this may be to do with the modelers creating models for their own sake. However, the use of a dedicated, and isolated modeling tool tends to help promote this. Personally I am a big fan of tools such as Omondo - the Eclipse plug-in that can create models from Java source code and source code from Java models. I like such tools because they are lightweight, do not get in the way of the modeling process and tend to restrict the creation of very large, and potentially meaningless, models.

Use Patterns gently

Design patterns are good things, yes? Not always. Due to their very nature, if a design includes a number of interacting design patterns the end result may become, at best, complex and, at worse, opaque and potentially useless. However, I sometimes wonder whether some designers try and show how clever they are by producing complex designs that encompass numerous design patterns. As Scott Ambler has said: "Use design patterns gently!"

Design with others

Of course most designers do not start out with the aim of producing overly complex designs and models. Actually achieving simplicity in design is a much harder thing to succeed at, than to strive for. One way to keep things simple is by designing with others. In my experience this tends to help to things stay focussed, to ensure that the designs remain meaningful and that they are as clear as possible given the application. It is essentially the design equivalent of XP's LINK pair programming.


In conclusion, it is important to note that I am not advocating simple design, but rather the goal should be to aim for the simplest design that fulfils its purpose. Thus we should aim for simplicity in design just as we should in actual implementation.®

Boost IT visibility and business value

More from The Register

next story
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
KDE releases ice-cream coloured Plasma 5 just in time for summer
Melty but refreshing - popular rival to Mint's Cinnamon's still a work in progress
Leaked Windows Phone 8.1 Update specs tease details of Nokia's next mobes
New screen sizes, dual SIMs, voice over LTE, and more
Another day, another Firefox: Version 31 is upon us ALREADY
Web devs, Mozilla really wants you to like this one
Put down that Oracle database patch: It could cost $23,000 per CPU
On-by-default INMEMORY tech a boon for developers ... as long as they can afford it
Secure microkernel that uses maths to be 'bug free' goes open source
Hacker-repelling, drone-protecting code will soon be yours to tweak as you see fit
Mozilla keeps its Beard, hopes anti-gay marriage troubles are now over
Plenty on new CEO's todo list – starting with Firefox's slipping grasp
prev story


Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.