Saturday, March 29, 2008

Evolution: The Fittest and the Sexiest

The topic of this blog is "SOA Evolution" so it seems overdue for me to look at the Evolution process. I coined this title to chronicle my organisation's slow but deliberate adoption of SOA. 'Evolution' seemed to be an appropriate term because it was both a slow process but one that would improve our applications. In this posting I will look at evolution more literally and find more appropriateness in the term than I first imagined.

I am reading a book by Richard Dawkins (see references below) on a range of topics but primary about evolution in biology. There are two principal evolutionary processes. One is the survival of the fittest and the other is sexual selection which is the process of influencing the evolution process by the choice of a mate. The success of evolution is its ability to adapt to its environment and to succeed against other species in that environment.

Natural adaptations are gradual and based on the parent life form. The history of the life forms can be discerned in the DNA of the life form. We can determine that humans evolved from an ancestor we share with Chimpanzees from looking at this DNA.

The process of survival of the fittest can be applied to software development technologies. We see various versions of programming languages replaced by later more effective versions. We see whole languages disappear into obscurity (eg. Algol, APL, SmallTalk, ADA) or replaced by new languages. Relational databases took over from set-based or network databases. Software development approaches have evolved from structured programming, to object-oriented programming to SOA. It has been mentioned that SOA was forged from marriage of distributed computing and document-based integration.

Extinction of old approaches is often not as complete as we would like. The Cobol programs and the old database technologies are still around. The old dinosaurs are hard to kill off completely.

As with any evolutionary process the origins of software development are evident when we dig deep. Visual Basic .NET is still saddled with some of the terminology and constructs that were around in DOS Basic. The kernel of some operating systems still contains some anachronisms which would not be used if it were not for historical reasons. Many software systems have parts that were written long ago or copied from other systems that no-one can maintain or just do not make sense in the context of software written today. Some software maintenance tasks are like archaeological expeditions. Unfortunately it is not passive fossils that the software archaeologist finds amongst the code. Some of these historical curiosities actually support critical business functions.

There are some principles from long ago that we do not want to discard though. Just like some of the primitive instincts and emotions buried in the core of our brain there are principles from long ago that should remain in our software. Procedures and functions still have a role in our software as do objects. The development of services does not replace the need for these other means of encapsulation. The principles for strong typing and structured programming still have as much value today as they did thirty years ago.

The mechanism for natural selection process in software technologies is not that different from the animal kingdom. Programmers will rewrite software using new techniques if requirements change. New tools outsell older tools that do not provide the same benefits. New techniques that reduce development time or improve quality replace old techniques.

Just as species become extinct old software technique die from disuse or replacement. Old code does not die off as quickly as some of us would like. It can last forever in our systems if the requirements it fulfils and infrastructure it uses do not shift too markedly.

Charles Darwin had two theories that he espoused in his books "The Origin of the Species" and "The Descent of Man". One could be paraphrased as 'survival of the fittest' and the other once was 'sexual selection'. Sexual selection is where a mate is selected because he or she is bigger, is stronger, is darker, has more colourful tail feathers or has less hair and therefore individuals with these characteristics tend to propagate.

I have briefly explained how the fittest software and development techniques succeed at the cost of inferior versions but it is also true that the sexiest software can be propagated despite any objective superiority. This can happen through good marketing or the support of a major company. Software standards are often agreed upon, even though they may not be the best based on an objective measure of quality. Often the benefit to adopt a standard exceeds the cost of the standard being suboptimal.

'Survival of the fittest' and 'sexual selection' are alive and well in the software industry. I expect SOA to remain an important part for the genetic makeup of future software development even after the term has lost its currency.


Dawkins, Richard, A Devil's Chaplain: Selected Essays, Phoenix 2003

Darwin, Charles, The Descent of Man, 1871,

Darwin, Charles, The Origin of the Species, 1859,

Monday, March 10, 2008

SOA in a Virtual World

Wikipedia defines a virtual world as a computer-based simulated environment intended for its users to inhabit it. Often a computer application is a business process made virtual by the use of computer technology. We therefore have to be careful when discussing the virtualization of computer environments as this may imply a virtual virtual reality.

The only example of virtual virtual reality I have seen is in a Futurama episode. It displayed an arcade booth with the label 'Virtual Reality' complete with a player using stereoscopic goggles and wired gloves. It then displayed another arcade booth with man sitting in a simple chair imaging he was wearing stereoscopic goggles and wired gloves. The caption to this booth was "Virtual Virtual Reality".

If we talk about "Virtual SOA" we must be talking about something that is not an SOA at all. Judith Hurwitz comes close to this when she discusses a "Virtualized SOA" in her article "Is virtualization the foundation of SOA?"

Andrew Doble writes about building a virtual SOA without investing in in-house software like an ESB. I would argue that this is in fact legitimate SOA. The only thing "virtual" about Andrew's suggestion is the ownership of the software tools.

Virtualization and SOA however do go together. Judith Hurwitz defines Virtualization as

"a technique for abstracting the physical characteristics of computing resources
in order to more easily leverage hardware systems, applications, operating
systems, networks, graphics, data or storage so they can be repurposed based on
customer need."

I believe that loose-coupling is the foundation of SOA but virtualization in many cases allows the benefits from this loose-coupling to be realised. The basic examples of virtualization are virtual servers, storage area networks and thin client platforms such as Citrix. These provide infrastructure flexibility for the deployment of SOA software. The design of the software for an application written using SOA is not affected. The SOA discipline should make sure that flexible deployment options can be used.

Manufacturers such as IBM are building business around SOA infrastructure. One thing to remember is that you do not need virtualization to build SOA. An SOA application can be built on a single server if you required, although it should also give you the flexibility to distribute this application and take advantage of virtualization options.

I agree with Lorraine Lawson in her posting "SOA and Virtualization: Complex, Fuzzy Ideas That Go Great Together? ". These two concepts mix well. However SOA is from the software development world and virtualisation is from the infrastructure world. We should beware of talking in terms of virtualizing our SOA. Our CIOs may consider we are sitting in a corner thinking we have an SOA when this is just a virtual reality.

Fry from "Futurama" with a virtual Lucy Liu.
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