Java Management Extensions

String Monitors

As we mentioned in the beginning of this chapter, a string monitor is used to monitor an MBean attribute that:

• Matches a predefined value

• Differs from a predefined value

• Is of type String

In this section, we will look at the agent code that shows how to use a string monitor. When using a string monitor, the first thing to do is to create a new instance of the StringMonitor class:

StringMonitor monitor = new StringMonitor(  );

After that, the following attributes of the string monitor must be set:

• ObservedObject

• ObservedAttribute

• StringToCompare

• NotifyMatch (must be set to true if a notification is to be sent when the derived gauge matches StringToCompare)

• NotifyDiffer (must be set to true if a notification is to be sent when the derived gauge differs from StringToCompare)

• GranularityPeriod

We discussed most of these attributes earlier in this chapter. When the derived gauge differs from StringToCompare and NotifyDiffer is set to true, a difference notification is sent. By the same token, if StringToCompare matches the derived gauge and NotifyMatch is set to true, a match notification is sent. The following example shows how to use both of these notifications in conjunction to monitor a String attribute:

try { StringMonitor monitor = new StringMonitor( ); monitor.setObservedObject(new ObjectName("UserDomain:name=Controller")); monitor.setObservedAttribute("OperatorName"); monitor.setNotifyMatch(true); monitor.setNotifyDiffer(true); monitor.setStringToCompare("Unassigned"); ...