The Cathedral and the Lemonade Stand

Software is big, hard and complicated. It has also traditionally been long-lived, often lasting beyond all the reasonable expectations of its creators.

These realities have driven a lot of software “best practices” in the last few years. Suites of tests to make sure the software is easy to change with confidence, the understanding that software needs to be complete in it itself rather than accompanied by auto-generated documentation files or 200 page manuals, the understanding that software is written to be read not to do things.

It has also led to more difficult arguments that have yet to be won. Things like the fact that software needs to be considered more like infrastructure, with ongoing costs. Most people realise that if they don’t clean their buildings they get dirty and if they don’t service their cars then eventually they stop working. Most people though are happy to pay large sums creating software only to avoid paying anything further and thereby creating a system that slowly slips into weed-ridden obsolescence.

It is this tendency to regard software as something you purchase once rather than an ongoing investment that I want to talk about here.

An interesting thing is starting to happen just now with the arrival of high-productivity languages such as Python and Ruby and flexible NoSql data solutions like CouchDb and key-value stores. Software is probably easier to create (without compromising the practices we’ve come to understand are important) now than ever before. It is also getting easier and easier to deploy applications with cloud services like Google App Engine and Heroku for the web and EC2 for raw machines.

In short we can now turn around software very quickly if chose to. This creates an interesting avenue for tackling the maintenance problem by caving in to what budget holders tend to do naturally. Budgets are generally spent on specific items of functionality. Maintaining that functionality as service tends to come out of a generalised pot, if at all. Normally arguments about solving this problem have focused on trying to include the true cost of the product into the initial budget.

But why? Why don’t we just create a piece of software and then later when we want it do something else through it away and start again. Take a lemonade stand. You don’t build a lemonade stand out of stone and marble with a team of master masons. When the hot weather comes round you grab some wood and cardboard and make a stand that will be good enough for the weekend or evening that you need it for. If next week it is still hot and you want to sell lemonade again you just make it again.

Websites are a lot like this, they get old very quickly and on the front end, they probably have a six-month lifecycle before design trends changes or new browser standards are implemented or some new way of using the web is discovered. Building a website to last four years (or the 10 or 20 years that key infrastructure software tends to be used for) is a waste of time, it’s very unlikely to repay your effort over it’s actual lifetime of, maybe, two years.

Even in software that does last 10 years there is often a feeling of regret that due to tremendous sunk costs in developing it it is not viable to move it to commodity hardware or the cloud or in the case of banking mainframe code make any change to it of any significance.

We can now develop really powerful applications in the timeframe of four to ten weeks. If that application lasts three months with no additional effort and we then spend another four to ten weeks replacing it, are we not actually better off? We are able to implement our lessons learnt sooner. Solutions are much more flexible and mistakes do not come with long-running costs attached. A bad idea can just be left as is.

I’m not arguing for a complete rewrite every three months, just like the lemonade stand we can reuse the good bits, our sign or the good piece of wood for the counter perhaps. Things like Guerilla SOA are taking us in these directions anyway with loosely coupled services with standard-based protocols and interchange formats. If we write a great authentication service we can keep that, or we could replace it with OAuth or OpenId. Our options are open and wider when we play in the short term rather than the long term.


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