/**
* Listen to events that happen only on local node.
*
* @throws IgniteException If failed.
*/
private static void localListen() throws IgniteException {
System.out.println();
System.out.println(">>> Local event listener example.");
Ignite ignite = Ignition.ignite();
IgnitePredicate<TaskEvent> lsnr =
evt -> {
System.out.println(
"Received task event [evt=" + evt.name() + ", taskName=" + evt.taskName() + ']');
return true; // Return true to continue listening.
};
// Register event listener for all local task execution events.
ignite.events().localListen(lsnr, EVTS_TASK_EXECUTION);
// Generate task events.
ignite
.compute()
.withName("example-event-task")
.run(() -> System.out.println("Executing sample job."));
// Unsubscribe local task event listener.
ignite.events().stopLocalListen(lsnr);
}
/**
* Executes example.
*
* @param args Command line arguments, none required.
* @throws Exception If example execution failed.
*/
public static void main(String[] args) throws Exception {
try (Ignite ignite = Ignition.start("examples/config/example-ignite.xml")) {
System.out.println();
System.out.println(">>> Events API example started.");
// Listen to events happening on local node.
localListen();
// Listen to events happening on all cluster nodes.
remoteListen();
// Wait for a while while callback is notified about remaining puts.
Thread.sleep(1000);
}
}
/**
* Listen to events coming from all cluster nodes.
*
* @throws IgniteException If failed.
*/
private static void remoteListen() throws IgniteException {
System.out.println();
System.out.println(">>> Remote event listener example.");
// This optional local callback is called for each event notification
// that passed remote predicate listener.
IgniteBiPredicate<UUID, TaskEvent> locLsnr =
(nodeId, evt) -> {
// Remote filter only accepts tasks whose name being with "good-task" prefix.
assert evt.taskName().startsWith("good-task");
System.out.println(
"Received task event [evt=" + evt.name() + ", taskName=" + evt.taskName());
return true; // Return true to continue listening.
};
// Remote filter which only accepts tasks whose name begins with "good-task" prefix.
IgnitePredicate<TaskEvent> rmtLsnr = evt -> evt.taskName().startsWith("good-task");
Ignite ignite = Ignition.ignite();
// Register event listeners on all nodes to listen for task events.
ignite.events().remoteListen(locLsnr, rmtLsnr, EVTS_TASK_EXECUTION);
// Generate task events.
for (int i = 0; i < 10; i++) {
ignite
.compute()
.withName(i < 5 ? "good-task-" + i : "bad-task-" + i)
.run(
new IgniteRunnable() {
// Auto-inject task session.
@TaskSessionResource private ComputeTaskSession ses;
@Override
public void run() {
System.out.println("Executing sample job for task: " + ses.getTaskName());
}
});
}
}