Not if you treat the application itself as the module to replace. Essentially your "new app" starts out as an http proxy in front of the old one, and then you i

Not if you treat the application itself as the module to replace. Essentially your "new app" starts out as an http proxy in front of the old one, and then you implement routes/modules in the new one one by one and replace the proxy w/ the new logic as it comes online.