Unlocking System Scalability and Flexibility with Event-Driven Architectures

Organizations must adopt event-driven architectures to overcome the limitations of their current systems. In doing so, they may uncover new opportunities for analysis and functionality that go beyond their original goals. We must embrace event-first thinking to build a strong foundation for event streaming platforms.

In the event-command pattern, the service is aware of the endpoints and API of other services and communicates with them. The event-first approach is beneficial when we need to improve the system. It is crucial to note that the event-driven approach allows many processors to respond to the same event broadcasted. Achieving decoupling is vital to this process.

Capture facts. Capture behavior. Provide a representation of the real world. Model use cases of how. Supports repeated evaluation and processing (a time machine). Provide horizontal scaling. Speak the same language as the business. This method does not need API coupling to a distant service. The emitter of the event doesn’t know which processors (or functions) will consume it, and the event becomes the API. This decoupling allows the consuming apps to change over time without any upstream changes required in the emitter.

Event-first analog: I enter a room, generate an “entered room” event, and the light turns on. This is a reaction to an event. Event-command analog: I walk into a room, *flip the light switch* and the light turns on. This is a command. In the event-first analog, I do not know and don’t ask for the lights to be turned on. Instead, a sensor detects my presence; it has the responsibility. This approach allows datasets to be cached in each service, preventing the need for cross-context calls. Yet, as workloads grow, combining more sources can become more challenging. When an event is emitted, it still determines which processors or functions will use it. This allows for decoupling, meaning that apps using the event can change without requiring changes in the emitter.

The benefit of the event-first process is that it allows for easy enhancements to the system. In a command-based pattern, the user handles knowing how to interact with the system.

[¹]: Event Modeling