#20 Advanced Event Sourcing

Marten is the most robust and feature rich solution for Event Sourcing in the .NET ecosystem. The Marten community and I got there through a lot of iteration and adaptation in reaction to the problems our community has faced in building real life systems using Event Sourcing. In this talk, let me share some of these lessons by going quite a bit beyond basic introduction to Event Sourcing material and get into some harder problems you'll eventually need to solve in real systems. Like concurrency issues in your code, and how to both protect your systems from concurrency issues and how to integrate queueing or modeling approaches that minimize the risk of concurrency in the first place. Scalability and system responsiveness are of course real issues too, and I'll share some of the work the Marten community has done to improve both. A potential downside in Event Sourcing is the potential need for system downtime when event definitions or the read side "projections" need to change, so I'll discuss the recent abilities we've introduced to allow for "blue/green deployments" and how to get much closer to zero downtime deployments. In all cases, I think the lessons learned from Marten in real usage and the approaches we've had to take will be applicable to any other platforms and tooling around event sourcing that you might be using today.