Applying Event Sourcing Patterns

In the previous chapter, we explored a prolific pattern in CQRS. This pattern encourages us to create a clear separation between code and data sources that govern read and write operations. With this kind of separation, we risk having our data out of sync in between operations, which introduces the need for additional techniques to ensure data consistency.

Even without CQRS, we must contend with the typical microservices pattern where each service is expected to have its own data store. Recall that there will be situations where data needs to be shared between services. There needs to be some mechanism that will adequately transport data between services so that they will remain in sync.

Event sourcing is touted as a solution to this issue, where a new data store is introduced that keeps track of all the command operations as they happen. The records in this data store are considered events and contain enough information for the system to track...