streamcruncher.test.func.generic
Class ClusterHealthTest

java.lang.Object
  streamcruncher.test.func.MultiStreamEventGenerator
      streamcruncher.test.func.generic.ClusterHealthTest

public abstract class ClusterHealthTest
extends MultiStreamEventGenerator

This Test demonstrates the use of the Extra parameters allowed in the In-built Aggregation functions. The $diff parameter provided, instructs the function to compute the difference between the New value and the Old value, instead of outputting the New value directly had the extra clause not been provided.

This example demonstrates a case where a Servers in a Datacenter keeps pinging the ESP Kernel with Heartbeat Events every 5 seconds. With the use of the pinned clause, the Partitions/Window remain in memory even if the Window becomes empty - when the Server fails to ping within 5 seconds; usually if the Server has gone down or the Network has partitioned. By using the count(xxcolumn $diff) function definition, the Window and hence the Aggregate remain in memory even if the Ping Event is not received in time. The "count" dips to 0 and the "diff" (New value - Old value) turns negative, which is when the Alarm is raised. The avg(..) function can also be used to identify missed alerts when the avgrage value becomes null.

There are 3 count(.. ) functions defined for levelb. One does not use the $diff clause and so, it provides the absolute count of Events over the past 5 seconds. Two of them use the $diff clause, out of which one uses a custom ClusterHealthTest.CountDiffBaselineProvider, which always uses 0 as the baseline. The other one, for which no custom Provider has been declared, uses the default Provider.

Thus, Aggregates can be used to detect Trends in the Stream.

This test uses only one Stream. The other Streams are dormant.

Nested Class Summary

static class	ClusterHealthTest.CountDiffBaselineProvider Custom Provider for the count function.
static class	ClusterHealthTest.StatsDiffBaselineProvider Custom Provider for the Statistics functions (avg,variance..).

Nested classes/interfaces inherited from class streamcruncher.test.func.MultiStreamEventGenerator

MultiStreamEventGenerator.Event, MultiStreamEventGenerator.EventType

Constructor Summary

ClusterHealthTest()

Method Summary

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ClusterHealthTest

public ClusterHealthTest()