MicroProfile 7.0 · org.eclipse.microprofile.metrics · APIdia, the JavaDoc alternative

MicroProfile Metrics

Rationale

To ensure reliable operation of software it is necessary to monitor essential system parameters. There is already JMX as standard to expose metrics, but remote-JMX is not easy to deal with and especially does not fit well in a polyglot environment where other services are not running on the JVM. To enable monitoring in an easy fashion, the MicroProfile Metrics specification provides a standard to instrument an application with metrics and provides a simple REST endpoint for integration with monitoring services.

Adding Metrics

MicroProfile Metrics provides 4 different metric types that can be used to instrument an application. Developers can create an accompanying Metadata object to supply the metric's name, description and units. Once the metric and the metadata are registered against the application MetricRegistry, the metrics will be available in the REST endpoints.

Metric Types

Counter is used to measure an increasing value.

Example usage:


    Counter count = metricRegistry.counter(metadata);
    count.inc();

Gauge is used to provide the immediate measurement of a value.

Example usage:


    Gauge<Double> temperature = new Gauge<Double>() {
        public Double getValue() {
            return getTemperature();
        }
    };
    metricRegistry.register(metadata, temperature);

Histogram is used to sample and compute the distribution of values

Example usage:


    Histogram histogram = metricRegistry.histogram(metadata);
    histogram.update(score);

Timer is used to measure the duration of an event as well as the frequency of occurrence.

Example usage:


    Timer timer = metricRegistry.timer(metadata);
    try (Timer.Context context = timer.time()) {
        ... // code that will be timed
    }

Interface Summary

Modifier and Type	Interface and Description
public interface	Counter An incrementing counter metric.
public interface	Counting An interface for metric types which have counts.
public interface	Gauge< the type of the metric's value. Must be numeric. T extends Number> A gauge metric is an instantaneous reading of a particular value.
public interface	Histogram A metric which calculates the distribution of a value.
public interface	Metadata Bean holding the metadata of one single metric.
public interface	Metric A tag interface to indicate that a class is a metric.
public interface	MetricFilter A filter used to determine whether or not a metric should be reported, among other things.
public interface	MetricRegistry The registry that stores metrics and their metadata.
public interface	Sampling An object which samples values.
public interface	Timer A timer metric which aggregates timing durations and provides duration statistics

Class Summary

Modifier and Type	Class and Description
public class	DefaultMetadata The default implementation of `Metadata`
public class	MetadataBuilder The `Metadata` builder.
public class	MetricID A unique identifier for `Metric` and `Metadata` that are registered in the `MetricRegistry` The MetricID contains: `Name`: (Required) The name of the metric. `Tags`: (Optional) The tags (represented by `Tag` objects) of the metric. The tag name must match the regex `[a-zA-Z_][a-zA-Z0-9_]*` (Ascii alphabet, numbers and underscore). The tag value may contain any UTF-8 encoded character.
public class	MetricUnits Standard units constants for metric's `Metadata`.
public abstract class	Snapshot A statistical snapshot of a `Snapshot`.
public class	Tag Tag represents a singular metric tag key and value pair.

Package org.eclipse.microprofile.metrics

Rationale

Adding Metrics

Metric Types

Interface Summary

Class Summary