JavaScript: Functional Programming for JavaScript Developers

Message upgrader

One of the highest-risk activities with some monolithic applications is upgrading. To do so you basically need to upgrade the entire application at once. With even a medium-sized application there are far too many aspects to reasonably test. Thus at some point you simply need to cut over from the old system to the new system. With a microservice approach, the cutover can be done for each individual service. Smaller services mean that the risk can be spread out over a long time and, should something go wrong, the source of the error can be more quickly pinpointed: the singular new component.

At issue are the services which are still talking to the old version of the upgraded service. How can we continue to serve these services without ...