I have been trying to figure out the preferred way of doing "Event Sourcing" while using the NestJS CQRS recipe (https://docs.nestjs.com/recipes/cqrs). I've been looking at the NestJS fra...

I’m currently learning about the Actor design pattern, or model, and it seems quite interesting. However, I’m struggling to find any decent real-world examples of how, or where, this model could be...

I have been reading about using Command objects to represent use cases that our domain exposes, and Command Handler objects to process those commands. For example: RegisterUserCommand RegisterUs...

I have a MediatR Pipeline behavior for validating commands with the FluentValidation library. I've seen many examples where you throw a ValidationException from the behavior, and that works fine fo...

I've got a simple document management system I'm putting together, I'm trying to follow solid DDD principals and things have been coming together. One area I've been questioning is what the cleanes...

Or is that considered bad practice or something? I have one notification triggers 4-5 handlers, which in turn call database to retrieve data. Each those calls can also be called separately,...

Recently I've read multiple times that two-phase commits are bad, but always as a side note. So there was never a good explanation with it. For example in CQRS Journey Chapter 5: Second, we're ...

What is the difference between CQRS (Command Query Responsibility Segregation) and Event Sourcing? I believe Event Sourcing is a type of CQRS. What distinguishes each, and what makes Event Sourcin...

I was looking in to event base architecture and came to know about two architecture Event Sourcing & Event Driven Architecture. My understanding is following Event driven : used for distribute...

I try to make .NET Core API with CQRS, but i cannot build it because of MediatR error: System.AggregateException: 'Some services are not able to be constructed (Error while validating the service ...

I know that CQRS can be implemented with or without event sourcing, but does it work the other side? Does event sourcing without CQRS make sense? If so, how it should be implemented?

What is the difference between commands and events in architectures that emphasize events? The only distinction I can see is that commands are usually sourced/invoked by actors outside the system, ...

My team and I have been discussing using the CQRS (Command Query Responsibility Segregation) design pattern and we are still trying to asses the pros and cons of using it. According to: http://mart...

I am working an ASP.NET Core 6.0 Web API project. I use the CQRS design pattern. I want to update an airlines table (code-first EF Core). So first I need to find the ID of airline. I have GetAirlin...

Danger ... Danger Dr. Smith... Philosophical post ahead The purpose of this post is to determine if placing the validation logic outside of my domain entities (aggregate root actually) is actually...

I am re-designing a dotnet backend api using the CQRS approach. This question is about how to handle the Query side in the context of a Kubernetes deployment. I am thinking of using MongoDb as the ...

I am using MediatR and CQRS in a real project using the Clean Architecture principles. Is it correct to: Call Command from NotificationHandler? Call Command in Command? Call Query in Command? ...

I'm currently evaluating options for designing/implementing Event Sourcing + CQRS architectural approach to system design. Since we want to use Apache Kafka for other aspects (normal pub-sub messag...

I am trying to implement event sourcing/CQRS/DDD for the first time, mostly for learning purposes, where there is the idea of an event store and a message queue such as Apache Kafka, and you have e...

I have an async controller and I am trying to call two different Async functions from it. like this public async void Approvefiles(string[] data) { var response = await _mediator.Send(new perso...

Although I've come across Kafka before, I just recently realized Kafka may perhaps be used as (the basis of) a CQRS, eventstore. One of the main points that Kafka supports: Event capturing/storing...

So for the login, since it doesn't really make anything new in the database but rather just returns if we've logged in, and possibly some user data, should it be a command or query? And as for the ...

I'm working on an application for managing bank credit cards. CQRS and Event Sourcing architecture was chosen for the app. The most important aggregate in the app is CreditCard which controls the c...

When we talk about sourcing events, we have a simple dual write architecture where we can write to database and then write the events to a queue like Kafka. Other downstream systems can read those ...

Currently I learn CQRS and DDD without Event Sourcing (not yet). I need to return from my repository to a query handler a model different from a domain model. Should I create a read model in a doma...