My presentation Building microservices with event sourcing and CQRS describes the challenges of functionally decomposing a domain model in a microservices based application. It shows that  a great way to solve those problems is with an event-driven architecture that is based on event sourcing and CQRS.

The presentation uses  a simple banking application, which transfers money between accounts, as an example. The application has the architecture shown in the following diagram:

Banking application architecture

The application consists of four modules that communicate only via events and can be deployed either together in a monolithic application or separately as microservices.

The four modules are as follows:

• Accounts – the business logic for Accounts
• Money Transfers – the business logic for Money Transfers
• Account View Updater – updates a denormalized view of Accounts and Money Transfers in MongoDB
• Account View Reader – queries the denormalized view

You can find the source code and documentation for the example application in this github repository. There are currently two versions of the application: Java+Spring Boot and Scala+Spring Boot. I plan to publish a Scala/Play version shortly. The application uses a simple, embedded event store.

Watch the presentation (slides+video), and take a look at the source code and documentation. It would be great to get feedback on the programming model.