This seems near-proof to me that a gradual inflight translation of a codebase from ANY one language, to another, entirely different one, is feasible, as long as you build a data interop layer of some sort (JSON, etc.). I imagine that if it were powering a web app, dual-deployment would become an additional (but potentially manageable) concern during the &quot;transition&quot; period.<p>This seems a much safer&#x2F;saner way to do total rewrites&#x2F;refactorings.<p>Note that it practically demands decent (if not impeccable) test coverage (he even admits that many parts were not tested... the only saving grace being that due to the semantics of the 2 specific languages here, he was able to use roughly the same logic for the less-tested portions, reducing risk).<p>Also note that according to the graph, during the middle of this process, application and testing performance will be <i>the most terrible.</i> At that point, some managers would probably decide to back out&#x2F;bail on it, which is why I thought it was important to note.