Observing throughput
Observability is essential for optimizing the throughput of our stream processors and our messaging channel topology. It helps us to understand the normal ebb and flow of events and to identify bottlenecks. It allows us to monitor the health of the system and react accordingly. Let's look at the important role domain events play as work metrics and how we can leverage the iterator age metric and alert on fault events.
Work metrics
In Chapter 2, Defining Boundaries and Letting Go, we discussed the importance of work metrics. These metrics identify the behavior of the system from the perspective of the end user. They represent the user visible output of the system.
Domain events are work metrics. They are the output of the system. They state the facts about the work the system has completed. We can perform valuable business analytics based on domain events. And we can leverage domain events to monitor the health of the system.
As work metrics, we...