Instrumenting For Metrics

Metrics are measurements at a given moment of a particular aspect of an application during runtime. An individual capture is called a metric event and consists of a timestamp, a measurement, and associated metadata. Metric events are used to provide an aggregated view of the behavior of an application at runtime. For example, a metric event can be a counter incremented by 1 when a request is handled by a service. The individual event is not especially useful. However, when aggregated into a sum of requests over a period of time, we can see how many requests are made to service over that period of time.