class AmbariReportingTask extends AbstractReportingTask {

    @Override
    public void onTrigger(final ReportingContext context) {
        final String metricsCollectorUrl = context.getProperty(METRICS_COLLECTOR_URL).evaluateAttributeExpressions().getValue();
        final String applicationId = context.getProperty(APPLICATION_ID).evaluateAttributeExpressions().getValue();
        final String hostname = context.getProperty(HOSTNAME).evaluateAttributeExpressions().getValue();

        final boolean pgIdIsSet = context.getProperty(PROCESS_GROUP_ID).isSet();
        final String processGroupId = pgIdIsSet ? context.getProperty(PROCESS_GROUP_ID).evaluateAttributeExpressions().getValue() : null;

        final long start = System.currentTimeMillis();

        // send the metrics from last execution
        if (previousMetrics != null) {
            final WebTarget metricsTarget = client.target(metricsCollectorUrl);
            final Invocation.Builder invocation = metricsTarget.request();

            final Entity<String> entity = Entity.json(previousMetrics.toString());
            getLogger().debug("Sending metrics {} to Ambari", new Object[]{entity.getEntity()});

            final Response response = invocation.post(entity);
            if (response.getStatus() == Response.Status.OK.getStatusCode()) {
                final long completedMillis = TimeUnit.NANOSECONDS.toMillis(System.currentTimeMillis() - start);
                getLogger().info("Successfully sent metrics to Ambari in {} ms", new Object[]{completedMillis});
            } else {
                final String responseEntity = response.hasEntity() ? response.readEntity(String.class) : "unknown error";
                getLogger().error("Error sending metrics to Ambari due to {} - {}", new Object[]{response.getStatus(), responseEntity});
            }
        }

        // calculate the current metrics, but store them to be sent next time
        final ProcessGroupStatus status = processGroupId == null ? context.getEventAccess().getControllerStatus() : context.getEventAccess().getGroupStatus(processGroupId);

        if(status != null) {
            final Map<String,String> statusMetrics = metricsService.getMetrics(status, pgIdIsSet);
            final Map<String,String> jvmMetrics = metricsService.getMetrics(virtualMachineMetrics);

            final MetricsBuilder metricsBuilder = new MetricsBuilder(factory);

            final JsonObject metricsObject = metricsBuilder
                    .applicationId(applicationId)
                    .instanceId(status.getId())
                    .hostname(hostname)
                    .timestamp(start)
                    .addAllMetrics(statusMetrics)
                    .addAllMetrics(jvmMetrics)
                    .build();

            previousMetrics = metricsObject;
        } else {
            getLogger().error("No process group status with ID = {}", new Object[]{processGroupId});
            previousMetrics = null;
        }
    }

}