The yarn event-driven model of Hadoop

Yran programming has many areas where the event-driven model is used, simplifying the code and making it easier to understand.

1. Define an event:

Import org.apache.hadoop.yarn.event.AbstractEvent;

public class Taskevent extends abstractevent<taskeventtype> {
	
	private String TaskID;
	
	Public Taskevent (String TaskID, Taskeventtype type) {
		super (type);
		This.taskid=taskid;
	}

	Public String GetTaskID () {
		return taskID;
	}

}

2. There are 2 types of this event:

public enum Taskeventtype {
	t_kill,
	t_schedule
}

3. Define a scheduler, and the test code is also written in:

Import org.apache.hadoop.conf.Configuration;
Import Org.apache.hadoop.service.CompositeService;
Import Org.apache.hadoop.service.Service;
Import org.apache.hadoop.yarn.conf.YarnConfiguration;
Import Org.apache.hadoop.yarn.event.AsyncDispatcher;
Import Org.apache.hadoop.yarn.event.Dispatcher;
										
Import Org.apache.hadoop.yarn.event.EventHandler;

	public class Simplemrappmaster extends Compositeservice {//Single Event Service can inherit Abstractservice, how to use it.
	
	Private Dispatcher Dispatcher;
	Public Dispatcher Getdispatcher () {return Dispatcher;
	} public Simplemrappmaster (String name) {super (name);
		} @Override protected void Serviceinit (Configuration arg0) throws Exception {dispatcher = new asyncdispatcher ();
		Dispatcher.register (Taskeventtype.class, New Taskeventdisptacher ());
		AddService (Service) dispatcher);
	Super.serviceinit (arg0); } Private class Taskeventdisptacher implements eventhandler<taskevent>{@Override public void handle (Taskeve NT arg0) {if (arg0.getType () = = Taskeventtype.t_kill) {System.out.println ("Run KILL");
			}else if (arg0.gettype () = = Taskeventtype.t_schedule) {System.out.println ("Run SCHEDULE"); }}}//test portal public static void main (string[] args) throws Exception {Simplemrappmaster master = new Simpl
		Emrappmaster ("Simplemrappmaster");
		Yarnconfiguration conf = new yarnconfiguration ();
		Master.serviceinit (conf);
Master.servicestart ();//Must be a subclass to be called, so the Main method writes to this class, and the main method writes to other classes, which need to be reflected.  Master.init (conf);     These 2 groups of methods test the effect looks the same,//Master.start ();
		Have time to see the API explained Master.getdispatcher (). Geteventhandler (). Handle (New Taskevent ("Task1", Taskeventtype.t_schedule));
	Master.getdispatcher (). Geteventhandler (). Handle (New Taskevent ("Task1", Taskeventtype.t_kill)); }
}

There are some problems, do not understand, first make a record it.