Archive For The “Refactoring” Category

Brownfield CQRS part 4 – Command Dispatcher

In the first two posts I talked about commands and command handlers. Now we need to wire them up to invoke them from your service endpoint. Brownfield CQRS part 1 – Commands Brownfield CQRS part 2 – Command Handlers Brownfield CQRS part 3 – Queries, Parameters and Results Brownfield CQRS part 4 – Command Dispatcher […]

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Brownfield CQRS part 3 – Queries, Parameters and Results

In the previous two posts, I showed some simple patterns for commands and command handlers. Now let’s talk about the other half of the story: queries! Brownfield CQRS part 1 – Commands Brownfield CQRS part 2 – Command Handlers Brownfield CQRS part 3 – Queries, Parameters and Results Brownfield CQRS part 4 – Command Dispatcher […]

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Brownfield CQRS part 2 – Command Handlers

In my previous post, I described command DTOs and service methods for booking a table at a restaurant. Now, we just need something to interpret this command, and do something useful with it. Brownfield CQRS part 1 – Commands Brownfield CQRS part 2 – Command Handlers Brownfield CQRS part 3 – Queries, Parameters and Results […]

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Brownfield CQRS part 1 – Commands

One question that came up several times at DDD eXchange last week was CQRS: now we understand all the benefits, how do we begin migrating our existing applications towards this sort of architecture? It’s something we’ve been chipping away at at work recently, and over a short series of posts I’d like to share some […]

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Try not to call your objects DTOs

Strictly speaking, the DTO (Data Transfer Object) pattern was originally created for serializing and transmitting objects. But since then, DTOs have proven useful for things like commands, parameter objects, events, and as intermediary objects when mapping between different contexts (e.g. importing rows from an Excel worksheet). One consequence of this widespread use is that, now […]

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