weka.experiment
Class RemoteEngine

java.lang.Object
  java.rmi.server.RemoteObject
      java.rmi.server.RemoteServer
          java.rmi.server.UnicastRemoteObject
              weka.experiment.RemoteEngine

All Implemented Interfaces:

Compute, java.rmi.Remote, java.io.Serializable

public class RemoteEngine

extends java.rmi.server.UnicastRemoteObject

implements Compute

A general purpose server for executing Task objects sent via RMI.

Version:

$Revision: 1.7 $

Author:

Mark Hall (mhall@cs.waikato.ac.nz)

See Also:

Serialized Form

Field Summary

private java.lang.String	m_HostName The name of the host that this engine is started on
private Queue	m_TaskIdQueue A queue of corresponding ID's for tasks
private Queue	m_TaskQueue A queue of waiting tasks
private boolean	m_TaskRunning Is there a task running
private java.util.Hashtable	m_TaskStatus A hashtable of experiment status

Fields inherited from class java.rmi.server.UnicastRemoteObject

Fields inherited from class java.rmi.server.RemoteServer

Fields inherited from class java.rmi.server.RemoteObject

ref

Constructor Summary

RemoteEngine(java.lang.String hostName)
Constructor

Method Summary

private void	addTaskToQueue(Task t, java.lang.String taskId) Adds a new task to the queue.
java.lang.Object	checkStatus(java.lang.Object taskId) Returns status information on a particular task
java.lang.Object	executeTask(Task t) Takes a task object and queues it for execution
static void	main(java.lang.String[] args) Main method.
private void	purge() Checks the hash table for failed/finished tasks.
private void	purgeClasses() Attempts to purge class types from the virtual machine.
private void	startTask() Checks to see if there are any waiting tasks, and if no task is currently running starts a waiting task.

Methods inherited from class java.rmi.server.UnicastRemoteObject

clone, exportObject, exportObject, exportObject, unexportObject

Methods inherited from class java.rmi.server.RemoteServer

getClientHost, getLog, setLog

Methods inherited from class java.rmi.server.RemoteObject

equals, getRef, hashCode, toString, toStub

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

m_HostName

private java.lang.String m_HostName

The name of the host that this engine is started on

m_TaskQueue

private Queue m_TaskQueue

A queue of waiting tasks

m_TaskIdQueue

private Queue m_TaskIdQueue

A queue of corresponding ID's for tasks

m_TaskStatus

private java.util.Hashtable m_TaskStatus

A hashtable of experiment status

m_TaskRunning

private boolean m_TaskRunning

Is there a task running

Constructor Detail

RemoteEngine

public RemoteEngine(java.lang.String hostName)
             throws java.rmi.RemoteException

Constructor

Parameters:

hostName - name of the host

Throws:

java.rmi.RemoteException - if something goes wrong

Method Detail

executeTask

public java.lang.Object executeTask(Task t)
                             throws java.rmi.RemoteException

Takes a task object and queues it for execution

Specified by:

executeTask in interface Compute

Parameters:

t - the Task object to execute

Returns:

an identifier for the Task that can be used when querying Task status

Throws:

java.rmi.RemoteException - if something goes wrong.

checkStatus

public java.lang.Object checkStatus(java.lang.Object taskId)
                             throws java.lang.Exception

Returns status information on a particular task

Specified by:

checkStatus in interface Compute

Parameters:

taskId - the ID of the task to check

Returns:

a TaskStatusInfo encapsulating task status info

Throws:

java.lang.Exception - if an error occurs

addTaskToQueue

private void addTaskToQueue(Task t,
                            java.lang.String taskId)

Adds a new task to the queue.

Parameters:

t - a Task value to be added

taskId - the id of the task to be added

startTask

private void startTask()

Checks to see if there are any waiting tasks, and if no task is currently running starts a waiting task.

purgeClasses

private void purgeClasses()

Attempts to purge class types from the virtual machine. May take some time as it relies on garbage collection

purge

private void purge()

Checks the hash table for failed/finished tasks. Any that have been around for an hour or more are removed. Clients are expected to check on the status of their remote tasks. Checking on the status of a finished/failed task will remove it from the hash table, therefore any failed/finished tasks left lying around for more than an hour suggest that their client has died..

main

public static void main(java.lang.String[] args)

Main method. Gets address of the local host, creates a remote engine object and binds it in the RMI registry. If there is no RMI registry, then it tries to create one with default port 1099.

Parameters:

args -