March 2025
Intermediate to advanced
202 pages
4h 45m
English
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Chapter 3Enforcing Perimeters with Injectors and Notifiers
So far, you’ve learned that an aggregate applies a function to a command to produce events. That same aggregate also applies another function to a stream of events to produce the internal state used for validating those commands. You’ve also seen that a projector takes a stream of events and produces query-friendly data views. In this chapter, you’ll get to experiment with two additional event sourcing building blocks: the injector and the notifier.
In pure functional programming terms, interaction with external systems is considered impure because those interactions are side effects. Different languages handle side effects in different ways, but in functional programming languages, ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.