Category Archives for DDD

UI Wireframe

How to Build a Master Details View when using CQRS and Event Sourcing

One of the most liberating things about the CQRS ES way, is the simplicity of the read side. However, if you are new to CQRS you may have wondered how it works. How for example, would it work for a classic master details view? You are not alone, in fact, I am writing this post in answer to exactly this question I found on stackoverflow:

“So my question is how are people handling a screen where by for example it displays a summary of customer details and then a list of their orders with a [more detail] link etc….”Continue reading

CQRS + Event Sourcing – A Step by Step Overview

A common issue I see is understanding the flow of commands, events and queries within a typical CQRS ES based system. The following post is designed to clear up what happens at each step. Hopefully this will help you to reason about your code and what each part does.Continue reading

Handling Concurrency Conflicts

Handling Concurrency Conflicts in a CQRS and Event Sourced system

Handling Concurrency Conflicts

Imagine if it was possible, when faced with a potential concurrency issue to programmatically check if any previous ‘events’ actually conflict with the current action being requested. With a CQRS Event Sourced application, it is possible to significantly reduce the problems of concurrency and in the remainder of this article I will show you how.

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