March 2025
Intermediate to advanced
202 pages
4h 45m
English
Content preview from Real-World Event SourcingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Handling Input and Output in an Event-Sourced World
As you’ve learned the building blocks in the first chapters of the book, you’ve also picked up a few rules worth going over again to help you understand why aggregates and projectors exist. One is that neither projectors nor aggregates are allowed to access the “wall clock,” which stems from the law that all data required must be on the events. If an aggregate’s state can be different after applying an event first thing in the morning versus late at night, then it’s no longer predictable and repeatable as required by aggregates. You’ll also see how accessing a real clock can ruin replays in Chapter 6, "Building Resilient Applications with Persistent Events," .
The other event sourcing law ...
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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.
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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.