You’re on the right lines with or a mockup – you need to mock the IMediator There’s a few mocking libraries out there: Moq FakeItEasy NSubstitute Moq is one of the most popular, so, using your test as an example: [Fact] public async void UpdateCustomerCommand_CustomerDataUpdatedOnDatabase() { //Arrange var mediator = new Mock<IMediator>(); UpdateCustomerCommand command = … Read more
NEventStore is a persistence agnostic event sourcing library for .NET with multiple storage options such as relational and document databases. EventStoreDB is a newer and high performing event sourcing solution with its own persistence engine and API’s for multiple protocols and languages. It has open source and commercial options. As far as I know you … Read more
Event Sourcing is optional and in most cases complicates things more than it helps if introduced too early. Especially when transitioning from a legacy architecture and even more when the team has no experience with CQRS. Most of the advantages being attributed to ES can be obtained by storing your events in a simple Event … Read more
Here is my take on this. CQRS + ES can make things a lot simpler in complex software systems by having rich domain objects, simple data models, history tracking, more visibility into concurrency problems, scalability and much more. It does require a different way thinking about the systems so it could be difficult to find … Read more
What is a saga in contrast to a process manager? The intent of these patterns is different. A process manager is a workflow pattern which can, as you say, be built on top of a state machine. A process manager will retain state between messages, and will contain logic in order to determine which action … Read more
CQS (Command Query Separation) and CQRS (Command Query Responsibility Segregation) are very much related. You can think of CQS as being at the class or component level, while CQRS is more at the bounded context level. I tend to think of CQS as being at the micro level, and CQRS at the macro level. CQS … Read more
The event store should not need to know about the specific fields or properties of events. Otherwise every modification of your model would result in having to migrate your database (just as in good old-fashioned state-based persistence). Therefore I wouldn’t recommend option 1 and 2 at all. Below is the schema as used in Ncqrs. … Read more
I am one of the original authors of Kafka. Kafka will work very well as a log for event sourcing. It is fault-tolerant, scales to enormous data sizes, and has a built in partitioning model. We use it for several use cases of this form at LinkedIn. For example our open source stream processing system, … Read more