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Derek Comartin

Competing Consumers Pattern for Scalability

The Competing Consumers Pattern enables messages from Message Queues (or Topics) to be processed concurrently by multiple Consumers. This improves scalability, availability but also has some issues that you need to consider such as message ordering and moving the bottleneck. YouTube Check out my YouTube channel where I post all kinds of content that accompanies my posts including this video showing everything that is in this post. Competing Consumers Pattern Message Queues are a great way to offload work to be that can be handled separately by another process. Meaning if you have a web application that takes an HTTP request, it… Read More »Competing Consumers Pattern for Scalability

Highly COHESIVE Software Design to tame Complexity

What is cohesion and why should you care? Highly cohesive software design can reduce complexity and coupling. But what is cohesion? It’s the degree to which the elements inside a module belong together. How you group operations together can have a widely different outcome on Cohesion. Informational Cohesion is grouped by operations on data. Functional Cohesion is grouped by operations of a task. It’s directly related to the Single Responsibility Principle, which you might also have a different definition of. YouTube Check out my YouTube channel where I post all kinds of content that accompanies my posts including this video showing everything… Read More »Highly COHESIVE Software Design to tame Complexity

Testing your Domain when Event Sourcing

How do you test your domain when Event Sourcing? I find testing aggregates with Event Sourcing to be simpler than testing if you’re storing the current state. The inputs to your aggregate are events and the output of your aggregate are events. Given a stream of events When a valid command is performedThen new event(s) occurs YouTube Check out my YouTube channel where I post all kinds of content that accompanies my posts including this video showing everything that is in this post. Event Sourcing I’ve covered Event Sourcing in my Event Sourcing Example & Explained in plain English post. So check… Read More »Testing your Domain when Event Sourcing