Last month, Dave Thomas came to Brisbane for YOW! Nights to deliver his always insightful and entertaining presentation entitled “Mature Legacy Seeking Sexy New Technology for Fun and Profit: Extracting Gold from Legacy Code”. It’s been a pleasure to work with Dave on the last couple of Agile Australia conferences and I always try to make sure I catch his presentations when he is in town.

The following are my notes from the session:

• a common complaint is that my boss does not let me do anything neat – legacy is a challenge
• go where there is a big need rather than wherever everybody is – solve a problem that is important to them in a clever way
• legacy code is code that has no tests
• only if you have a product that matters you will have legacy – you can make bloatware even in new systems
• legacy – the big ball of mud – OO is one of the biggest creators of technical debt
• developers are the source of legacy debt – the developer solution is we can always rewrite it in my language – most rewrites fail
• outsourcing often works short term – but you lose your business knowledge and you realise your requirements stink
• vendor solution – start with a technology you don’t need
• agile solution – just refactor it, there are no tools or practices that can fix millions of lines of code, it will take forever
• need to figure out what the legacy is about – get the metaphor and a picture – write stories and put them on a wall, invest in getting the legacy programmers to sit down and talk about it
• most companies are living on their legacy – new products are not paying the way
• pair legacy and non-legacy developers to tackle the problem
• use modern IDE, use modern SCM, new continuous build infrastructure is cheap, need fewer developers if your whole world is in memory
• when everybody is using agile, how can it be the best practice – it is the only practice
• prove your way through the old systems – there are very few greenfield projects
• do TDD using live transaction roll back
• automate from the data definition not screen scrape
• people only do innovation when they are screwed – agile is predictability and quality not productivity
• rewrite the contracts so that vendors can only install if they have automated acceptance tests – acceptance tests are the only way of putting two distinct processes together
• big resource contracts should be split because the quality of resources are usually spilt in half – give it to local resources who have the talent
• an agile coach is “an unemployed Smalltalk programmer”
• think outside of the box – use spreadsheets to load data to the cloud
• simple innovation in a difficult problem gets you a lot of respect – don’t ask your boss if you should write some Prolog to solve a problem
• look where the customers are spending money – it is usually in legacy
• lots of great opportunities to make a difference to hold your nose with the legacy smell – find where the biggest bang for buck is quickly – need to do it in months
• KLOCs kill – more code to maintain
• prove new ideas and do a little bit at a time