When working with a poorly-written or unstable legacy app, there is a middle ground approach. Rather than rewrite the whole thing (often impossible), or introdu

When working with a poorly-written or unstable legacy app, there is a middle ground approach. Rather than rewrite the whole thing (often impossible), or introduce a new framework in the app, you can draw a circle around a core subsystem and rewrite just that component as a microservice. This frees you from the (often) monolithic app, gives you the freedom to pick an entirely different language, if you want, and leaves you with a part of the app that any new developer could completely wrap their head around.