Design more decoupled services with one weird trick - Udi Dahan - NDC Oslo 2024

Coupling is one of the biggest and oldest problems in software development - moving it around with different architectural patterns doesn’t solve the fundamental issue

Event-driven architecture alone doesn’t reduce coupling - it often just moves the coupling into events with large payloads of shared data

Vertical slice architecture helps by splitting functionality into independent vertical slices instead of horizontal layers, but data coupling often remains at the database level

Generating IDs upfront (the “weird trick”) allows services to collect and store their own data independently, indexed by that ID, rather than passing large data payloads between services

Past tense events (things that already happened) work better than using events for commands/requests - this maintains proper event-driven patterns

Complex workflows can be broken down into independent sub-workflows where each piece can succeed or fail independently

Business requirements often determine technical architecture decisions - like legal requirements around pricing and advertising affecting how data must be handled

Microservices don’t automatically solve coupling issues - sharing databases or passing large amounts of data between services maintains tight coupling

Data snapshots (like pricing) should be taken early in workflows to maintain consistency through the process

Front-end and back-end architectures need to align - micro-frontends can help maintain proper service boundaries and data ownership