Strangler Things: How To De-Risk Legacy Code Migrations

Interview:

What key takeaways can attendees expect from your InfoQ Dev Summit session?

• An overview of how the Strangler Fig pattern can reduce risk in legacy code migrations
• Strategies for handling unexpected requirements in the midst of a legacy code migration
• Practical tips from a real-world example for how to effectively leverage Strangler Fig to perform legacy code migrations

What's the focus of your work these days?

I'm working on another migration of some legacy code. That means I'm doing lots of archeology into long-untouched systems and reverse engineering existing behavior. Doing these types of updates, I've learned how important it is to not just think about the existing behavior and ensure you don't break anyone's workflows but also to keep in mind the next iteration of these user experiences.

Do we have opportunities to reduce customer cognitive load or leverage automation to make things easier? Even if you aren't making those changes in the initial migration work, engineering the next generation of systems with future improvements in mind can make a big difference.

What technical aspects of your role are most important?

Lately, it's been reasoning about good tech debt vs bad tech debt. All code is a liability, and the code we're writing today is the legacy code of tomorrow. A lot of our technical decisions come down to navigating tradeoffs between current requirements and anticipating future needs.

How does your InfoQ Dev Summit Boston session address current challenges or trends in the industry?

Any organization that's existed for really any time at all has some amount of legacy code. Often we find ourselves needing to update legacy systems while customers need to continue using whatever system we're trying to update. It's rare to be able to take large periods of downtime, especially for SaaS applications. These upgrades are needed to meet business requirements, technical requirements, or both. As long as we have legacy code, we'll need to leverage strategies to minimize risk and customer pain.

How do you see the concepts discussed in your InfoQ Dev Summit Boston session shaping the future of the industry?

Strangler Fig is 20 years old this year, so it isn't exactly on the cutting edge of tech. But the longer our technology lives, the more legacy code we have to wrangle. For many companies, the code that got us where we are won't get us where we ultimately need to go, so leveraging well-worn patterns to work through those inevitable code migrations can make those migrations less painful.