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Tag Archive for cqrs

Inheritance, commands and event sourcing

In order not to redo things several times I wanted to factorize common stuff. For Instance, let’s say we have a cow and a horse. The cow produces milk, the horse runs fast, but both eat grass.

Distinguishing between UI command & domain commands

I am building a WPF client application using the MVVM pattern that provides an interface on top of an existing set of business logic residing in a library which is shared with other applications. The business library followed a domain-driven architecture using CQRS to separate the read and write models (no event sourcing). The combination of technologies and patterns has brought up an interesting conundrum:

CQRS with Repository pattern and Inversion of Control (with DI)

I assigned a POC project to someone where I asked to implement both Command Query Responsibility Segregation, Inversion of Control (with Dependency Injection) and Repository pattern. “Someone” gave me a POC solution project but I am not sure whether this is the way it is done. I will brief here about the POC project

CQRS and validations

I’m starting to introduce myself in CQRS concepts, but I get stucked with the following situation:
Supouse you have an entity that must have an unique name. In order to verify that, prior to create the entity you must make a query, thus you are verifing against the query subsystem.
But what happens if the syncronization has not been happened between the command system and the query system yet? Other client just had sent the same name before you.
What happens in that case?

CQRS and validations

I’m starting to introduce myself in CQRS concepts, but I get stucked with the following situation:
Supouse you have an entity that must have an unique name. In order to verify that, prior to create the entity you must make a query, thus you are verifing against the query subsystem.
But what happens if the syncronization has not been happened between the command system and the query system yet? Other client just had sent the same name before you.
What happens in that case?