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An Example of Planning AMI Methods

Let us suppose you have a transaction-processing application that needs to be monitored so that its message queue length doesn't grow too large. Instances of this application might make up a fault-tolerant group with primary/secondary status, which you want to autonomously monitor but also to interactively control.

Defining these needs, you could list two items:

•	The manager should retrieve the application’s queue length on a periodic basis.

•	The manager should retrieve the application’s primary/secondary status on a periodic basis.

You now create these methods:

•	getQueueLength, which takes no arguments and returns the queue length.

•	getFTStatus, which takes no arguments and returns the fault-tolerant status (primary or secondary) of the application.

•	makePrimary, which takes no arguments and sets the fault-tolerant status of the application instance to primary.

•	makeSecondary, which takes no arguments and sets the fault-tolerant status of the application instance to secondary.

Since you will be using a TIBCO Hawk agent as the manager, you build a rulebase with two rules, as follows:

•	The first rule has as its data source the getQueueLength method. It raises an alert if the queue length is greater than 200.

•	The second rule has as its data source the getFTStatus method. It sends a notification each time there is a fault-tolerant state transition.

From the TIBCO Hawk WebConsole, operators can control the fault-tolerant state of any instance of the application by invoking the makePrimary or makeSecondary methods.

Other possible AMI examples might include:

•	Methods to dynamically control trace or debug levels.

•	Methods to drop or re-request information from data streams.

•	Methods to monitor client connections for server applications.

•	Methods to control application backup procedures.

•	Methods to extract internal state information used in debugging.

•	Methods to change various application configuration parameters.

•	Methods that instruct applications to write their new configuration parameters to configuration files or to the Microsoft Windows registry.

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