Microservices: how to handle foreign key relationships

Question

Microservices architecture suggest that each service should handle it\'s own data. Hence any service (Service A) dependent on data owned by other service (service B) should acce

Answer 1

first solution: API Composition

 Implement a query by defining an API Composer, which invoking the
 services that own the data and performs an in-memory join of the
 results

second solution: CQRS

Define a view database, which is a read-only replica that is designed to support that 
query. The application keeps the replica up to data by subscribing to Domain events 
published by the service that own the data.