Revisiting the CQRS pattern

Command Query Responsibility Segregation (CQRS) applies the Command Query Separation (CQS) principle. Compared to what we saw in Chapter 16, Mediator and CQS Patterns, we can push CQRS further using microservices or serverless computing. Instead of simply creating a clear separation between commands and queries, we can divide them even more using multiple microservices and data sources to enhance scalability and flexibility. This approach allows each component to be scaled independently based on demand, improving system performance and resource efficiency.

CQS is a principle stating that a method should either return data or mutate data, but not both. On the other hand, CQRS suggests using one model to read the data and one model to mutate the data.

Serverless computing is a cloud execution model where the cloud provider manages the servers and allocates the resources on-demand, based on usage and configuration. Serverless resources fall...