Event store should fire events that are used by external systems

[imvision]

Typical use of events published by event store are to maintain materialized views and integration with other systems.

[jacqueskang]

Hi @imvision I decided not to adresse firing events for external systems because data stores usually support triggering events natively (e.g., DynamoDB Stream or CosmosDB change feed) Otherwise one can always implement publishing events in domain repositories, or by inheriting the event stores provided in this library.

[imvision]

I was just doing some proof of concept for an accounting system using file persistence and realized that there was no way to build read models. Now I want to use MSSQL for the read model but only if the event store could trigger events after aggregates are persisted successfully. I guess I can create a base repository that can handle the publishing of events for all the inherited domain repos.

Thanks for response.

[BenjaminCharlton]

I hope you don't mind me posting this hear, Jaques. It seems relevant to this question.

I have built three libraries that extend yours so that it can be used to fire integration events used by external systems.

I have created base classes and interfaces that can be extended to use any ORM, database and dependency injection framework. I have also provided a full implementation for EF Core, SQL Server and Microsoft.Extensions.DependencyInjection.

They use the DotNetCore.CAP library to publish the integration events only when the domain event has been persisted successfully to the event store. I.e. using the "Outbox Pattern".

They are here: https://github.com/BenjaminCharlton/JKangEventSourcingWithCap

They can also be downloaded as Nuget packages. I hope it's helpful. I would welcome feedback (especially contributions) from you or anybody else interested.