edu.vub.at.actors.natives
Class ELVirtualMachine

java.lang.Object
  edu.vub.at.actors.eventloops.EventLoop
      edu.vub.at.actors.natives.ELVirtualMachine

All Implemented Interfaces:

DiscoveryListener, org.jgroups.blocks.RequestHandler

public final class ELVirtualMachine

extends EventLoop

implements org.jgroups.blocks.RequestHandler, DiscoveryListener

A ELVirtualMachine represents a virtual machine which hosts several actors. The virtual machine is in charge of creating connections with other virtual machines and orchestrates the broadcasting of its presence, the exchange of service descriptions and messages. It also contains a set of runtime parameters (such as the objectpath and initfile) which are needed to initialise a new actor. TODO: use pure JChannel to send pure async messages rather than using a MessageDispatcher? Or use dispatcher only for message transmission. TODO: urgently clean up the vm address book: race conditions exist wher ELFarRefs query the address book when there is no entry for the remote VM's address

Author:

tvcutsem, smostinc

Nested Class Summary

Nested classes inherited from class edu.vub.at.actors.eventloops.EventLoop

EventLoop.EventProcessor

Field Summary

private static java.lang.String	_GROUP_NAME_ the name of the multicast group joined by all AmbientTalk VMs
ELDiscoveryActor	discoveryActor_
private ATAbstractGrammar	initialisationCode_ startup parameter to the VM: the code of the init.at file to use
private java.util.Hashtable	localActors_ a table mapping actor IDs to local native actors (int -> ELActor)
MembershipNotifier	membershipNotifier_ the JGroups discovery bus for this Virtual Machine
org.jgroups.blocks.MessageDispatcher	messageDispatcher_ the JGroups communication bus for this Virtual Machine
private SharedActorField[]	sharedFields_ startup parameter to the VM: the list of fields to be initialized in every hosted actor
private org.jgroups.Address	vmAddress_ the JGroups Address of the VM
VMAddressBook	vmAddressBook_ A table mapping VM GUIDs to Address objects.
private GUID	vmId_ the GUID of this VM

Fields inherited from class edu.vub.at.actors.eventloops.EventLoop

eventQueue_, processor_

Constructor Summary

ELVirtualMachine(ATAbstractGrammar initCode, SharedActorField[] fields)

Method Summary

static ELVirtualMachine	currentVM()
void	event_actorCreated(ELActor actor) Event that signals the creation of a new actor on this virtual machine.
void	event_goOffline() Signals that this VM must disconnect from the underlying network channel
void	event_goOnline() Signals that this VM can connect to the underlying network channel and can start distributed interaction.
void	event_memberJoined(org.jgroups.Address remoteVMAddress) Notifies the discovery manager that a VM has joined the network.
void	event_memberLeft(org.jgroups.Address virtualMachine)
ELActor	getActor(int id)
SharedActorField[]	getFieldsToInitialize()
GUID	getGUID()
ELVirtualMachine	getHost()
ATAbstractGrammar	getInitialisationCode()
org.jgroups.Address	getLocalVMAddress()
void	handle(Event event) An event loop handles events by dispatching to the event itself.
java.lang.Object	handle(org.jgroups.Message message)
private void	initializeNetwork()
void	memberJoined(org.jgroups.Address virtualMachine)
void	memberLeft(org.jgroups.Address virtualMachine)

Methods inherited from class edu.vub.at.actors.eventloops.EventLoop

currentEventLoop, execute, owner, receive, receiveAndWait, receivePrioritized, stopProcessing, toEventLoop, toString

Methods inherited from class java.lang.Object

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

Field Detail

_GROUP_NAME_

private static final java.lang.String _GROUP_NAME_

the name of the multicast group joined by all AmbientTalk VMs

See Also:

Constant Field Values

initialisationCode_

private final ATAbstractGrammar initialisationCode_

startup parameter to the VM: the code of the init.at file to use

sharedFields_

private final SharedActorField[] sharedFields_

startup parameter to the VM: the list of fields to be initialized in every hosted actor

vmId_

private final GUID vmId_

the GUID of this VM

vmAddress_

private org.jgroups.Address vmAddress_

the JGroups Address of the VM

vmAddressBook_

public final VMAddressBook vmAddressBook_

A table mapping VM GUIDs to Address objects. Each time a VM connects, it sends its GUID and an entry mapping that GUID to its current Address is registered in this table. When a remote reference needs to send a message to the remote object, the VM is contacted based on its GUID and this table. When a VM disconnects, the disconnecting address is removed from this table.

localActors_

private final java.util.Hashtable localActors_

a table mapping actor IDs to local native actors (int -> ELActor)

messageDispatcher_

public org.jgroups.blocks.MessageDispatcher messageDispatcher_

the JGroups communication bus for this Virtual Machine

membershipNotifier_

public MembershipNotifier membershipNotifier_

the JGroups discovery bus for this Virtual Machine

discoveryActor_

public final ELDiscoveryActor discoveryActor_

Constructor Detail

ELVirtualMachine

public ELVirtualMachine(ATAbstractGrammar initCode,
                        SharedActorField[] fields)

Method Detail

currentVM

public static final ELVirtualMachine currentVM()

getGUID

public GUID getGUID()

getInitialisationCode

public ATAbstractGrammar getInitialisationCode()

getFieldsToInitialize

public SharedActorField[] getFieldsToInitialize()

getHost

public ELVirtualMachine getHost()

handle

public void handle(Event event)

An event loop handles events by dispatching to the event itself. Not to be confused with this class' handle(Message) method, which enables the VM event loop to handle incoming JGroups Messages!

Specified by:

handle in class EventLoop

Parameters:

event - the event object which was dequeued and which should be processed

getActor

public ELActor getActor(int id)

getLocalVMAddress

public org.jgroups.Address getLocalVMAddress()

memberJoined

public void memberJoined(org.jgroups.Address virtualMachine)

Specified by:

memberJoined in interface DiscoveryListener

memberLeft

public void memberLeft(org.jgroups.Address virtualMachine)

Specified by:

memberLeft in interface DiscoveryListener

event_goOnline

public void event_goOnline()

Signals that this VM can connect to the underlying network channel and can start distributed interaction.

event_goOffline

public void event_goOffline()

Signals that this VM must disconnect from the underlying network channel

event_memberJoined

public void event_memberJoined(org.jgroups.Address remoteVMAddress)

Notifies the discovery manager that a VM has joined the network. This VM may be a first-time participant or it may be a previously disconnected VM that has become reconnected. The VM asks the newly joined VM whether it has any services that match the type of an outstanding subscription on this VM.

event_memberLeft

public void event_memberLeft(org.jgroups.Address virtualMachine)

event_actorCreated

public void event_actorCreated(ELActor actor)

Event that signals the creation of a new actor on this virtual machine.

handle

public java.lang.Object handle(org.jgroups.Message message)

Specified by:

handle in interface org.jgroups.blocks.RequestHandler

initializeNetwork

private void initializeNetwork()