private TimelineMetrics getTimelineMetricsFromCache(TimelineAppMetricCacheKey metricCacheKey,
          String componentName) throws IOException {
      // Cache only the component level metrics
      // No point in time metrics are cached
      if (metricCache != null
          && !StringUtils.isEmpty(componentName)
          && !componentName.equalsIgnoreCase("HOST")
          && metricCacheKey.getTemporalInfo() != null) {
        return metricCache.getAppTimelineMetricsFromCache(metricCacheKey);
      }

      Long startTime = (metricCacheKey.getTemporalInfo() != null) ? metricCacheKey.getTemporalInfo().getStartTimeMillis():null;
      Long endTime = (metricCacheKey.getTemporalInfo() != null) ? metricCacheKey.getTemporalInfo().getEndTimeMillis():null;

      return requestHelper.fetchTimelineMetrics(uriBuilder, startTime, endTime);
    }
The information required to make a single call to the Metrics service.
ambari-server/src/main/java/org/apache/ambari/server/controller/metrics/timeline/AMSPropertyProvider.java