Version of this talk from Lean Agile Schotland 2015 Each and every time, the situation is the same: a big, messy code-base, few (if any) tests and many production issues. It’s no accident that, when he joined what would be the first XP team, the first thing Kent Beck said was: “*Let’s scrap it!*” Even with a world class team, these problems can be almost insurmountable. And we don’t usually start out with world class teams. Learning all the XP practices is hard enough without a Big Ball (of Mud) and Chain holding you back. So maybe we should rebuild. But the Agile way: incrementally, iteratively, and with close involvement from the business. Using examples from practice, I’ll show that: - We can set up a clear, loosely coupled architecture around the existing system, so we can replace parts while its running - We are then free to use all our modern practices for the new parts, and start Continuous Delivery from the first sprint - We can closely involve the business to surface the actually needed functionality, and build up Living Documentation in the process - We can get even an inexperienced team using and accepting practices such as TDD and ATDD quickly Learning Outcomes: The audience will see how extending some existing approaches to system improvement can give teams working on legacy systems renewed energy and belief (through experience) that high quality is possible.

1. Don’t Refactor.
Rebuild.
Kinda.
Wouter Lagerweij
@wouterla
Lean Agile Scotland - 6/10/2015

6. Rebuild?

7. Why you shouldn’t
● What was it supposed to do?
● What did it end up doing?
● Do we still want that?
● Why would it be better now?
● No new new things, or playing catch-up?

8. So...
● Deliver new value from day one
● Focus on quality
● Change your process
● Be specific in what you want now

9. In Practice
● Strangler Pattern
● Continuous Delivery
● BDD

10. DB
request for website A
Legacy system

11. DB
website A
Legacy system
Incoming request
New Page
Service
Incoming request
for new page

12. DB
website A
Legacy system
Incoming request
for job detail page
New Page
Service
Incoming request
for other pages
feature
toggle
?

13. “Every Push To Production”
Continuous Delivery

14. BDD

16. Test
Acc
Prod
VPN
docker
docker
docker

17. In one month
● legacy system
● few tests
● manual deploys
● 1 release per week
● timid team
● decoupled services
● 100% coverage
● full automation
● 30 releases per day
● courage

19. @wouterla
Wouter Lagerweij
http://www.lagerweij.com/
Thank You!