Answers
What is the strangler pattern?
In short
The strangler pattern modernises legacy software by progressively replacing functionality at the edge while the old system keeps running, until the old system can be safely retired.
Short answer
The strangler pattern modernises legacy software by progressively replacing functionality at the edge while the old system keeps running, until the old system can be safely retired.
What this actually means in practice
It's the antidote to the big-bang rewrite. Identify slices that can be carved out cleanly; route traffic to the new slice; prove parity; expand. Retire the old code only when nothing depends on it. It's slower per slice but vastly more likely to ship than a rewrite.
The most common pitfall
Stalling on the first slice because nobody decided how to route traffic between old and new.
What to do next
Pick one bounded slice with measurable success criteria and ship it.
Frequently asked questions
Does Forth Systems help with this?
Yes — Forth Systems works with banks, payment institutions, insurers and infrastructure operators on exactly this kind of work. Engagements start with a fixed-scope assessment so you see the shape before committing.
How experienced is the team?
Engagements are staffed by named, UK-based senior engineers — not a rotating offshore pool. References from the second line of comparable clients are available on request.
Where are you based?
Edinburgh-based, delivering UK-wide with onsite presence in London and across Scotland as required.
How fast can we start?
Most engagements start within 2-4 weeks of a signed SoW, faster where an existing supplier framework is in place.