This blog series will introduce you to building event-driven microservices as cloud-native applications.
In this first post, we’ll explore how to implement the CQRS pattern in microservices. We’ll also dive into why serverless is a natural fit for these kinds of systems. Later in the series we’ll explore a reference application that uses Spring Cloud Stream to implement CQRS.
What is an event-driven architecture?
Event-driven architectures treat domain events as first-class citizens. This approach is as old as software itself.
One example we use every day is in front-end applications. In every web browser in use today, events are handled as a way to capture inputs of a user form. Events connected to page elements are handled by an explicitly mapped function, sometimes referred to as an action or command, which will apply state changes to a user interface when triggered.
Now, more recently, with the widespread adoption of microservices, there is renewed interest in how to take advantage of event-driven techniques in distributed back-end systems.
CQRS
One of the most popular practices in event-driven architectures today is called CQRS, which is short for Command Query Responsibility Segregation. CQRS is a style of architecture that allows you to use different models to update and read domain data.
The basic idea of CQRS is that it’s perfectly natural to need to separate the models you’re using to update and read data. The diagram above shows this basic idea.
