Category Archives for Architecture

How to Upgrade CQRS Events Without Busting Your Event Stream

Events are at the heart of a CQRS Event Sourced system. Which is why changing or upgrading them can be problematic. In this post I’m going to cover a few principles to bear in mind, which should help you avoid hitting the rocks. Before I dive into  ‘how to upgrade CQRS events’ I’m going to recap the role Events play in the system.Continue reading

Is a 100% Provable Audit Log Possible? – Hint, with Event Sourcing it Is and I’ll Show You How

If you’ve been developing for any length of time you’ve probably had to create an audit log. Here’s the question though, are any of these logs, a 100% provable audit of all changes in the system? I’m guessing not. With event sourcing, a 100% provable event log just happens to be a handy by product. So how does it work and how can you implement it?

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‘Messaging’, the new silver bullet?

I had an ‘Ah ha!’ moment just over a year ago when I attended a Greg Young’s CQRS and Event sourcing course with skillsmatter. The ‘Ah ha’ wasn’t about CQRS, or even Event sourcing, it was about how Greg structured his code to work with messages. This approach can have far reaching effects on your software, making it simpler, easier to test and much more flexible. It can even remove the need for an AOP framework (amongst other things).Continue reading