Defining an Event Provider

An event provider defines the types of events for the operations that generate statistics for an add-on component.

To define an event provider, write a Java^TM language interface that defines the types of events for the component. In the interface, define one method for each type of event that is related to the component.

You are not required to implement the event provider interface. After you register the event provider, Enterprise Server generates the implementation class at runtime for you. For more information, see Registering an Event Provider.

Identifying the Event Type

If you overload a method in your implementation, annotate each form of the method with the @org.glassfish.flashlight.provider.annotations.ProbeName annotation to uniquely identify the event type. Set the value element of the @ProbeName annotation to the name of the event type.

If you do not annotate a method, the name of the event type is the method name. Therefore, you are not required to annotate methods that are not overloaded.

Specifying Event Parameters

To enable methods in an event listener to select a subset of values, annotate each parameter in the method signature with the org.glassfish.flashlight.provider.annotations.ProbeParam annotation. Set the value element of the @ProbeParam annotation to the name of the parameter.

Example of Defining an Event Provider

Example 5–1 Defining an Event Provider

This example shows the definition of the TxManager interface. This interface defines events for the start and end of transactions that are performed by a transaction manager.

The methods in this interface are as follows:

onTxBegin

This method sends an event to indicate the start of a transaction. The name of the event type that is associated with this method is begin. A parameter that is named txId is passed to the method.

onCompletion

This method sends an event to indicate the end of a transaction. The name of the event type that is associated with this method is the method name. A parameter that is named outcome is passed to the method.

import org.glassfish.flashlight.provider.annotations.ProbeName;
import org.glassfish.flashlight.provider.annotations.ProbeParam;

  public interface TxManager {
    
    @ProbeName("begin")
    public void onTxBegin(
        @ProbeParam("{txId}") String txId
    );

    public void onCompletion(
        @ProbeParam("{outcome}") boolean outcome
    );
 }