edu.vub.at.actors.net.cmd
Class VMCommand

java.lang.Object
  edu.vub.at.actors.net.cmd.VMCommand

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

CMDHandshake, CMDInitRequireServices, CMDJoinServices, CMDProvideService, CMDRequireService, CMDTransmitATMessage

public abstract class VMCommand

extends java.lang.Object

implements java.io.Serializable

VM Command objects are the message objects that AT/2 virtual machines send to one another. They are control objects sent by one VM and received by another. The receiving VM executes the VM Command object's uponReceiptBy method, which allows the command object to encapsulate the reception code itself. By convention, all VM Command classes are prefixed with CMD.

Author:

tvcutsem

See Also:

Serialized Form

Field Summary

static int	_TRANSMISSION_TIMEOUT_ the default transmission timeout for JGroups synchronous message communication
private java.lang.String	description_

Constructor Summary

VMCommand(java.lang.String descr)

Method Summary

protected void	sendAsyncMulticast(org.jgroups.blocks.MessageDispatcher dispatcher) Sends this VM Command object asynchronously to all connected VMs.
protected void	sendAsyncUnicast(org.jgroups.blocks.MessageDispatcher dispatcher, org.jgroups.Address recipientVM) Sends this VM Command object asynchronously to the recipient VM.
protected java.lang.Object	sendSynchronousUnicast(org.jgroups.blocks.MessageDispatcher dispatcher, org.jgroups.Address recipientVM) Sends this VM Command object synchronously to the recipient VM.
java.lang.String	toString()
abstract java.lang.Object	uponReceiptBy(ELVirtualMachine remoteHost, org.jgroups.Message wrapper) To be overridden by subclasses to specify the behaviour to execute upon reception and execution of the command object at the recipient VM.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

description_

private final java.lang.String description_

_TRANSMISSION_TIMEOUT_

public static final int _TRANSMISSION_TIMEOUT_

the default transmission timeout for JGroups synchronous message communication

See Also:

Constant Field Values

Constructor Detail

VMCommand

public VMCommand(java.lang.String descr)

Parameters:

descr - for debugging purposes

Method Detail

toString

public java.lang.String toString()

uponReceiptBy

public abstract java.lang.Object uponReceiptBy(ELVirtualMachine remoteHost,
                                               org.jgroups.Message wrapper)
                                        throws java.lang.Exception

To be overridden by subclasses to specify the behaviour to execute upon reception and execution of the command object at the recipient VM. This code is still executed in a JGroups thread!

Parameters:

remoteHost - the host at which the command arrived and is executed

wrapper - the JGroups message wrapper that was used to transport this command object

Throws:

java.lang.Exception

sendAsyncUnicast

protected void sendAsyncUnicast(org.jgroups.blocks.MessageDispatcher dispatcher,
                                org.jgroups.Address recipientVM)
                         throws org.jgroups.TimeoutException,
                                org.jgroups.SuspectedException

Sends this VM Command object asynchronously to the recipient VM.

Throws:

org.jgroups.TimeoutException

org.jgroups.SuspectedException

sendAsyncMulticast

protected void sendAsyncMulticast(org.jgroups.blocks.MessageDispatcher dispatcher)
                           throws org.jgroups.TimeoutException,
                                  org.jgroups.SuspectedException

Sends this VM Command object asynchronously to all connected VMs.

Throws:

org.jgroups.TimeoutException

org.jgroups.SuspectedException

sendSynchronousUnicast

protected java.lang.Object sendSynchronousUnicast(org.jgroups.blocks.MessageDispatcher dispatcher,
                                                  org.jgroups.Address recipientVM)
                                           throws org.jgroups.TimeoutException,
                                                  org.jgroups.SuspectedException

Sends this VM Command object synchronously to the recipient VM. The recipient's address must be given, null is not allowed (i.e. broadcasting synchronously is not allowed)

Throws:

org.jgroups.TimeoutException

org.jgroups.SuspectedException