Event sourcing and CQRS resources

Event Sourcing and CQRS resources

Articles

This page from the Lagom Documentation explains why Event sourcing is useful. Advantages of Event Sourcing

Exploring CQRS and Event Sourcing This link is from a Microsoft project and is an excellent resource about CQRS and Event Sourcing. It walks you through the entire decision process of breaking down an entire application domain with basic Domain Driven Design concepts. It is very thorough and a great read to help you understand what goes into CQRS, Event sourcing and breaking your domain into smaller more useable chunks.

CQRS increases consistency.  This article is another good short argument for why you should use CQRS.

CQRS Documents by Greg Young

CQRS Clarified by Udi Dahan

Message brokers vs Message buses These two sound the same but are different this article covers the minor details.

What do you mean by “Event-Driven”. This is an excellent article by Martin Fowler which covers Event driven systems in more detail.

Event Sourcing and CQRS with AKKA 2.6 video. This page has a video, but it also has some really useful links below the video which is why  I included it as a link.

How to use CQRS with Akka 2.6 video. This page has a video like the one above with useful links.
Using Akka and Scala for CQRS and Event Sourcing – great in depth article about Event sourcing

Books

Patterns, Principles and Practices of Domain-Driven Design by Scott Millett and Nick Tune This book covers Event Sourcing and CQRS as well as all of the other principles of Domain Driven Design. The nice thing about this book is it has code examples, the code is C#, but you don’t have to down load it to view it and basically follow along. The examples often come after long explanations of the concepts, if you have time or know C# you can download and try the example code, a nice extra if you ask me.  This is one that stays in a pile next to my desk.

Designing Event-Driven systems. This is a free ebook so what does it hurt to read it?

Distributed Data for Microservices — Event Sourcing vs. Change Data Capture

Videos

Greg Young – CQRS and Event Sourcing – Code on the Beach 2014

Greg tells some great stories that relate to why CQRS and Event Sourcing are useful and gives interesting insights into use cases. For many of us who have been doing the old fashioned CRUD architecture of storing and reading everything from a database, this video will make sense of why that was a bad way of doing things. After this video you will really want to dig into CQRS and Event Sourcing in depth.

CQRS and Event Sourcing with Lagom by Miel Donkers

An Introduction to CQRS and Event Sourcing Patterns – Mathew McLoughlin

In this video Mathew explains how an Event Sourced system that utilizes CQRS works. One thing covered is why having separate read and write data stores is a good idea and how it works in an abstracted way.

Event Sourcing You are doing it wrong by David Schmitz

I like this video this guy is funny. David quickly covers Microservices, event sourcing and other Domain Driven Design concepts, tying things together in a very entertaining animated and funny way. This is one of my favorite videos about event sourcing, it answers a lot of questions and makes many good points. This video is worth watching more than once.

Allard Buijze – Talk Session: The Inconveniences of Event Sourcing

This video has some good abstract information about events and event sourcing in microservices. It points out some of the issues with event sourcing and how to overcome them. Allard covers the types of Events, commands, events, queries and how they are used in an event driven system. The most interesting and for me useful part of this video is the part about GDPR and how to comply in an Event Sourced system at about the 38:00 mark.

Martin Kleppmann — Event Sourcing and Stream Processing at Scale

Udi Dahan – If (domain logic) then CQRS, or Saga?

Udi tells a story that builds up to CQRS and Sagas. He says in CQRS that Commands can’t be allowed to fail. At about 27:00 he explains what this means. At ~31:00 he talks about eventual consistency and how to deal with it in a system. At about 40:00 give them the Rick Sanchez slow  ramp. LOL He finishes up by talking about bounded contexts.