October 2016
Intermediate to advanced
436 pages
11h 31m
English
Content preview from Mastering AkkaBecome 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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CQRS in the event sourced world
We know from our work in Chapter 4, Making History with Event Sourcing, that an event-sourced app is all about commands (actions) and events (reactions to those commands). The events that are generated from these commands are used to represent the state of a given entity over time, with the past events being replayed whenever the current state of an entity is needed. The storage model itself does not store the current state, only the occurrences that lead to a current state for a particular entity.
Given this model, what can I do if I want to query for a particular entity that has the current state with a field matching a specified value? If I don't store the current state, how can I answer this question? Will I ...
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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.
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.