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CQRS

CQRS without Multiple Data Sources

One of the most common misconceptions about CQRS is it implies Eventual Consistency. That you must have different data sources for your commands and queries. Meaning you will have a use one data source for commands/writes and an entirely different data source for query/reads. This is simply untrue. This assumption implies that you’re query/read data source will be eventually consistent with the command/write side. This is because the assumption is your commands will write to its data source, then emit events that will be processed and update your query/read database independently. If you’re unfamiliar with CQRS, I highly recommend checking… Read More »CQRS without Multiple Data Sources

eShopOnContainers a Microservice based .NET Core Sample Application

Finding good sample applications if pretty difficult, if not impossible.  Most are small Todo style applications that are generally very CRUD based.  Thankfully Microsoft has created the eShopOnContainers a Microservice based .NET Core Sample Application. .NET Core reference application, powered by Microsoft, based on a simplified microservices architecture and Docker containers. This reference application is cross-platform at the server and client side, thanks to .NET Core services capable of running on Linux or Windows containers depending on your Docker host, and to Xamarin for mobile apps running on Android, iOS or Windows/UWP plus any browser for the client web apps. The… Read More »eShopOnContainers a Microservice based .NET Core Sample Application

Find MediatR Requests without Handlers

You’ve run into it.  MediatR throwing an InvalidOperationException when you didn’t have a matching handler for a request.   There’s a fairly simple solution to prevent this: Find MediatR Requests without Handlers. So here’s some quick code you can throw in a unit test to verify you don’t have any missing handlers. Find MediatR Requests without Handlers View the code on Gist. The above code uses reflection to get all the IRequest<>, RequestHandler<> and RequestHandler<,>.  Also worth mentioning it leverages Autofac for the IsClosedTypeOf method in the linq query. Usage Here’s a quick unit test that shows it’s usage for finding… Read More »Find MediatR Requests without Handlers