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Tag Archives: CQRS

CQRS increases consistency

I hear this argument a lot. As the author of a framework that strongly encourages CQRS, I obviously am biased against this opinion, and disgaree with it. Of course, the statement and my disagreement needs context and qualification. If you have a traditional monolithic system, where all data operations are done on a single database, and that single database supports ...

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Event-Sourcing and CQRS in Practise

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Anyone that has tried to implement a fully ACID compliant system knows that there are a lot of considerations you have to do. You need to make sure database entities can be freely created, modified and deleted without the risk of errors, and in most cases, the solution will be at the cost of performance. One methodology that can be ...

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CQRS with Java and Lagom

I’ve had the pleasure to talk at the Chicago Java User Group and talk about how Lagom implements CQRS, the Command Query Responsibility Segregation pattern. Thankfully, there is a recording and I also published the slides on slideshare.                 Abstract: As soon as an application becomes even moderately complex, CQRS and an Event Sourced ...

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Rapid Development with Hibernate in CQRS Read Models

In this post I’m going to share a few tricks for using Hibernate tooling in CQRS read models for rapid development. Why Hibernate? Hibernate is extremely popular. It’s also deceptively easy on the outside and fairly complex on the inside. It makes it very easy get started without in-depth understanding, misuse, and discover problems when it’s already too late. For ...

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Persistence in CQRS Read Models

One of the biggest benefits of CQRS is the ability to implement multiple read models. Business rules and the domain model are safe, clean and isolated over in the write model. They are not getting in the way of view models, which can selectively pick the pieces they are interested in, freely reshape them, and do everything in a way ...

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Writing an Event-Sourced CQRS Read Model

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Discussions about event sourcing and CQRS seem to usually focus on the overall system architecture or various flavors of domain-driven design in CQRS context. However, the read models are often neglected, even though there are some interesting considerations on this side as well. In this post we’re going to present a sample implementation of populating a view model by consuming ...

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Achieving Consistency in CQRS with Linear Event Store

In a recent project involving an event-sourced CQRS system, we decided to do some things that seem somewhat unusual compared to solutions mostly talked about. However, they let us achieve some nice properties that would be hard (if possible at all) otherwise. Event Store as Regular Table We decided to implement the event store as a regular table in an ...

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