Data Consistency Across Microservices

Question

While each microservice generally will have its own data - certain entities are required to be consistent across multiple services.

For such data consistency requiremen

Answer 1

I think you can approach this issue from 2 angles, service collaboration and data modelling:

Service collaboration

Here you can choose between service orchestration and service choreography. You already mentioned the exchange of messages or events between services. This would be the choreography approach which as you said might work but involves writing code in each service that deals with the messaging part. I'm sure there are libraries for that though. Or you can choose service orchestration where you introduce a new composite service - the orchestrator, which can be responsible for managing the data updates between the services. Because the data consistency management is now extracted into a separate component, this would allow you to switch between eventual consistency and strong consistency without touching the downstream services.

Data modelling

You can also choose to redesign the data models behind the participating microservices and to extract the entities that are required to be consistent across multiple services into relationships managed by a dedicated relationship microservice. Such a microservice would be somewhat similar to the orchestrator but the coupling would be reduced because the relationships can be modelled in a generic way.