Adding Statistics for a Component to the Monitorable Object Tree

Adding statistics for a component to the monitorable object tree makes the component and its statistics monitorable objects.

Adding a statistics for a component to the monitorable object tree involves the following tasks:

• Creating a TreeNode object to represent the component in the monitorable object tree

• Creating objects to represent the component's statistics in the monitorable object tree

• Getting the server node object

• Adding each object to the tree

Creating a TreeNode Object to Represent a Component

To a create a TreeNode object to represent a component in the monitorable object tree, invoke the static method createTreeNode of the org.glassfish.flashlight.datatree.factory.TreeNodeFactory class. Invoke this method in the class that represents your component.

In the invocation of the createTreeNode method, pass the following information as parameters to the method:

• A string that contains the name of the node

• An instance of the class that represents the component

• A string that describes the category of the component

Creating Objects to Represent a Component's Statistics

Create one object to represent each statistic that you are adding to the monitorable object tree. Create the objects in your listener class or in the class that represents your add-on component. Each object must be an implementation of an interface that extends org.glassfish.flashlight.datatree.TreeNode.

The TreeNode is an unstable interface and is subject to change.

To specify the name of the node in the monitorable object tree that the object represents, invoke the object's setName method. In the invocation of the setName method, pass a string that contains the name of the node as a parameter to the method.

The object that represents a statistic must also provide methods for computing the statistic from event data.

The org.glassfish.flashlight.statistics package provides the following utility classes to gather and compute statistics data:

Average

Provides averages.

Counter

Provides a counter that a class can use to maintain count.

TimeStats

Provides timing information in seconds.

TimeStatsMillis

Provides timing information in milliseconds.

TimeStatsNanos

Provides timing information in nanoseconds.

The classes in the org.glassfish.flashlight.statistics package are unstable interfaces and are subject to change.

The org.glassfish.flashlight.statistics.factory package provides a factory class for each utility class as shown in the following table.

Getting the server Node Object

The server node object is the parent of the TreeNode object that represents the component in the monitorable object tree.

To get the server node object, invoke the get method of the org.glassfish.flashlight.MonitoringRuntimeDataRegistry class. In the invocation of the get method, pass the string server as a parameter.

Adding an Object to the Tree

To add an object to the tree, invoke the addChild method of the object's parent object. In the invocation of the addChild method, pass the TreeNode object that you are adding as a parameter.

The parent object depends on whether the object represents an add-on component or a statistic:

• If the object represents an add-on component, the parent is the server node object.

• If the object represents a statistic, the parent is the TreeNode object that represents the add-on component.

Dotted Names for an Add-On Component's Statistics

The Enterprise Server administrative commands get(1), list(1), and set(1) locate a statistic through the dotted name of the statistic. The dotted name of a statistic for an add-on component is determined from the names of the TreeNode objects that represent the statistic and the component in the monitorable object tree as follows:

server.componenent-treenode-name.statistic-treenode-name

componenent-treenode-name

The name of the TreeNode object that represents the component in the monitorable object tree. This name is passed In the invocation of the createTreeNode method that creates the object. For more information, see Creating a TreeNode Object to Represent a Component.

statistic-treenode-name

The name of the TreeNode object that represents the statistic in the monitorable object tree. This name is passed In the invocation of the setName method. For more information, see Creating Objects to Represent a Component's Statistics.

Example of Adding Statistics for a Component to the Monitorable Object Tree

Example 5–6 Adding Statistics for a Component to the Monitorable Object Tree

This example shows the code for adding the totaltransactioncount statistic to the monitorable object tree. To add this statistic, objects are added to the monitorable object tree as follows:

• The component that is represented by the class TransactionManagerImpl is added as a child of the server node of the tree. The name of the node is tx. The category is transactions. The dotted name of the monitorable object that represents the component is server.tx.

• The totaltransactioncount statistic is added as a child of the tx node of the tree. The dotted name of the monitorable object that represents the statistic is server.tx.totaltransactioncount.

...
import org.glassfish.flashlight.client.ProbeListener;
import org.glassfish.flashlight.datatree.TreeNode;
import org.glassfish.flashlight.datatree.factory.TreeNodeFactory;
import org.glassfish.flashlight.statistics.Counter;
...
public class TransactionManagerImpl {

    @Inject
    private MonitoringRuntimeDataRegistry mrdr;

    private TreeNode serverNode;
    private Counter totalTxCount = CounterFactory.createCount();

    public void init (){
        ...
        TreeNode txNode = TreeNodeFactory.createTreeNode("tx", null, "transactions");
        TreeNode serverNode = getServerNode();
        serverNode.addChild(txNode);
        ...
        totalTxCount.setName("totaltransactioncount");
        txNode.addChild(totalTxCount);
        ...
    }
...
    private TreeNode getServerNode() {
        TreeNode serverNode = null;
        if (mrdr.get("server") != null) {
            serverNode = mrdr.get("server");
        } else {
            serverNode = TreeNodeFactory.createTreeNode("server", null, "server");
            mrdr.add("server", serverNode);
        }
        return serverNode;
    }
...
}