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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Evolving Projections and Projectors
Projections are disposable. They’re the output of a function applied to an event stream and are never used by aggregates or process managers to make decisions. The reason why projections are disposable is that the data in a projection is not used by business logic and is only used as a consumer-facing read model. In other words, nothing on the inside of the perimeter of your event-sourced system relies on a given projection.
Let’s say you have a user-profile projector, and it produces the user profile projection based on user-related events. Every time a UserProfileChanged event occurs, this projection changes. With version 1 of the projector, it stores the user’s first name and surname combined in a single ...
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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.