Reporting models and Event Sourcing

As a listened more of the Ask me anything with Udi Dahan session organised by Virtual DDD, more points, which Udi was making, especially about Event Sourcing, made my fingers itch to wrote some more. When talking about the natural progression in system evolution once it’s in production, Udi gave an example of adding columns in the read-model as a consequence of more properties to some domain objects. That particular example was about the search feature. [Read More]

Event-driven startup

During the last year, I’ve done quite a few webinars, talks and workshops about Event Sourcing. A lot of time the audience answered a question: when I should not use this pattern. In broader terms, the question appeared during the Ask me anything with Udi Dahan session organised by Virtual DDD. The question was: what are the circumstances, where things like Event-Driven Architecture (EDA), Service-Oriented Architecture (SOA), CQRS, et al., aren’t applicable. [Read More]

Event Sourcing and Microservices

This post is a part of the Event Sourcing introduction series that I wrote for Event Store. All the articles are available in the Event Store Blog, along with other great articles about Event Sourcing. Over the last few years, the microservices pattern became known and well-adopted. The promise of microservices is appealing - create small autonomous components, eliminate dependencies, enable team autonomy. Low coupling and high cohesion - the holy grail of software development seems feasible to achieve when using microservices. [Read More]

Projections in Event Sourcing

This post is a part of the Event Sourcing introduction series that I wrote for Event Store. All the articles are available in the Event Store Blog, along with other great articles about Event Sourcing. By definition, a projection is a representation of an object using a different perspective. For example, isometric and orthographic projections allow us to represent a 3D object on paper using different points of view. [Read More]

Event Sourcing and CQRS

This post is a part of the Event Sourcing introduction series that I wrote for Event Store. All the articles are available in the Event Store Blog, along with other great articles about Event Sourcing. CQRS stands for Command-Query Segregation Principle. Greg Young described (and named) the pattern thoroughly in 2010, but the idea existed way before that time. On a high level, CQRS states the fact that operations that trigger state transitions should be described as commands and any data retrieval that goes beyond the need of the command execution, should be named a query. [Read More]

Entities as event streams

This post is a part of the Event Sourcing introduction series that I wrote for Event Store. All the articles are available in the Event Store Blog, along with other great articles about Event Sourcing. In the introduction post, we got an overview of what is Event Sourcing and what the domain event is. In this guide, we can change the way we persist entities using events. The code in this article is C#-styled pseudo code. [Read More]

Event Sourcing basics

This post is a part of the Event Sourcing introduction series that I wrote for Event Store. All the articles are available in the Event Store Blog, along with other great articles about Event Sourcing. What is Event Sourcing Event Sourcing is an alternative way to persist data. In contrast with state-oriented persistence that only keeps the latest version of the entity state, Event Sourcing stores each state mutation as a separate record called an event. [Read More]

Global event stream

This post is a part of the Event Sourcing introduction series that I wrote for Event Store. All the articles are available in the Event Store Blog, along with other great articles about Event Sourcing. The previous post describes projection basics. However, subscribing to a single event stream that represents an entity (for example) isn’t useful. The projection code can handle any event that comes from the domain model and build sophisticated read models that serve a variety of needs. [Read More]

Hey, where is the UI part!?

TDLR; Chater 13 is currently being finalised and it has some UI bits. Will be published online only by the end of June. More content will be in the book repo in July and in this blog. I got quite a few questions from the readers of my book about the “missing chapter” and the part that should cover the user interface. Both are apparently missing from both the printed and electronic version. [Read More]
ddd  book 

The book is done!

Today, I wrote the final chapter for my book Hands-on Domain-Driven Design with .NET Core. There’s some more work to be done by the publisher and I expect them to ask for final adjustments. The book will go to print some time next week. Unfortunately, due to time pressure, the publisher has decided to exclude the last chapter from the printed version, so it will only be published online. You can get the book on Amazon or via Packt’s own webshop, where you often can get a bargain for the eBook. [Read More]
ddd  book