Appropriated from https://github.com/kosmisk-dk/ee-stats with permission of original author by original author

An EJB to depend on in a ee-project, that supplies:

• a jolokia.html index file with stats (and pie chart) from the application
• jolokia/ the jolokia servlet
• jolokia/name a text file providing the first found value of
  1. Environment variable $JOLOKIA_NAME
  2. Environment variable $APPLICAITON_NAME
  3. the application name as declared in the ee container
• Annotations to provide stats using metric
  1. @Counted - simple counter
  2. @Metered - @Counted + Rate of calls
  3. @Timed - @Metered + durations of calls
  4. @LifeCycleMetric - class level annotation needed for the other 3 to work ok Constructor, @PostConstruct and @PreDestroy. If this is needed but not supplied, an EJBException is thrown on startup. If it's present, but unneeded, an error is logged.

This is only for Beans example:

Simple bean invocations

@Stateless
@Path("foo")
public class Foo {

    @GET
    @Path("now")
    @Produces(MediaType.TEXT_PLAIN)
    @dk.dbc.ee.stats.Timed // @Metered or @Counted
    public String now() {
        return Instant.now().toString();
    }
}

LifeCycle measurements

@Stateless
@LifeCycleMetric
public class Foo {

    @PostConstruct
    @Timed
    public void init() {
        // Something time consuming
        // like initialization of JavaScript environment
    }
}

Remember measurements can only be made on bean-method invocations, ie. this.method() cannot me measured. One workaround is, Make a bean with business logic, and invoke the methods needed to accomplish the task, this way you can measure which part of the process that takes time.

You can inject:

1. MetricRegistry
2. Counter
3. Meter
4. Timer

Counter/Meter/Timer gets fully qualified name as JMX metric name unless annotated with @ExposeAs("name").

example

in pom.xml

<dependencies>
    ...

    <dependency>
        <groupId>dk.dbc</groupId>
        <artifactId>ee-stats</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>

    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>7.0</version>
        <scope>provided</scope>
    </dependency>
</dependencies>