Most systems I've seen these days don't have any compile-time type checking, since they're all written in Ruby, Python, or Node.js. In the normal case of devel

Most systems I've seen these days don't have any compile-time type checking, since they're all written in Ruby, Python, or Node.js. In the normal case of development, you tend to have a broken-out system. For a game for example: + Game code --+ User authentication classes/functionality (which accesses DB) --+ Messaging classes/functionality (which accesses DB) --+ User metrics classes/functionality (which accesses DB) In the new design you'd have this: + Game code --+ User authentication classes/functionality (which accesses REST service) --+ Messaging classes/functionality (which accesses REST service) --+ User metrics classes/functionality (which accesses REST service) In other words, in a clean design, your Game code is accessing a library which provides user Authentication functionality, one which provides Messaging functionality, and one which provides Metrics functionality. In this new design, you have exactly the same thing - a library which abstracts the details of communicating with the service, encoding data, etc. A person making changes to those libraries, which other services use, is responsible for either not making backwards-incompatible changes, or, when that isn't possible, working with other teams to ensure a clean upgrade path (or doing it themselves, if your lines are sufficiently blurred).