An interesting problem is whether the complexity is unavoidable and if it is, we need to teach migration and proxying in Software Engineering 101. We have an o

An interesting problem is whether the complexity is unavoidable and if it is, we need to teach migration and proxying in Software Engineering 101. We have an old app: dotnet webforms, it's clearly hanging on for its life and needs replacing but the mythical rewrite is impossible if you intend to rebuild and switch, it just involves too much time away from your core product. Instead, we had to setup a proxy which could send all traffic between one of the two apps so we can move things a few at a time to the new system and all new work just gets built in the new system. It still takes a long time so I am now wondering whether as soon as we finish, we should immediately setup another new app alongside the current new one and repeat indefinitely. It certainly wasn't easy to do because old and new frameworks are rarely able to share cookie formats/sessions etc so some hand-cranking was required.