drm.core
Class Node

java.lang.Object
  |
  +--drm.agentbase.Base
        |
        +--drm.core.Node

All Implemented Interfaces:

Contributor, Controller, IAgent, IBase, IDRM, Observer, java.lang.Runnable, java.io.Serializable

public final class Node

extends Base

implements Observer, Contributor, Controller, IDRM

This class extends Base to become a DRM node. A node is a member of the DRM (distributed resource machine) collective, a collective which has the goal of serving distributed applications. The agents living in a Node are given the chance to observe the DRM. The agents can cast the IBase object set through setBase into the type IDRM, and they can access information about the DRM through it.

All communication is implemented via the standard Base messaging interface, the low level protocol is not extended.

See Also:

IDRM, IAgent.setBase(IBase), Serialized Form

Inner classes inherited from class drm.agentbase.Base

Base.Firewall

Fields inherited from class drm.agentbase.Base

AGENT, boxes, cfg, GET_JAR, group, GROUP_MISMATCH, ISALIVE, MESSAGE, name, NOT_OK, OK, PROTOCOL_VERSION, RELEASE_VERSION, SENDING_DIR

Constructor Summary

Node(java.util.Properties cfg)
Calls super constructor.

Method Summary

void	addNodes(java.util.Properties cfg) Adds the peers defined in cfg to the default peer list of the collective.
void	close() Calls super implementation and after that closes the collective.
void	collectiveUpdated(ContributionBox peer) Stores the peer, and performs new commands.
IRequest	fireMessage(Address recipient, java.lang.String type, java.lang.Object content) The observer must provide this method to allow requesting information.
java.util.Set	getCommands() The controller has to return the new commands it intends to execute in the collective.
java.lang.Object	getContribution() The contributor has to return its contribution to the common repository when asked through this method.
ContributionBox	getContribution(java.lang.String nodeName) Returns the contribution that belongs to the given node name.
java.util.List	getContributions() Returns all known contributions in the DRM collective.
Base.Firewall	getFirewall() This method should return the firewall that is given to the agents.
ContributionBox	getNewestContribution() Returns the most up-to-date contribution.
Address[]	getPeerAddresses() Returns always null.
java.lang.String	getType() Returns "Node".
boolean	handleMessage(Message m, java.lang.Object object) Handles message type "collectiveUpdate-"+getJob().
void	invokeCommand(NodeCommand command) Invokes the command on the DRM.
void	invokeCommandLocally(NodeCommand command) Invokes the command only on this local node.
IRequest	launch(java.lang.String method, IAgent agent, java.lang.Object par) Adds implementation of launch method "RANDOM".
void	onArrival(Address from, Address to) Connects to the DRM collective.
java.lang.String	toString()

Methods inherited from class drm.agentbase.Base

addListener, destroyAgent, dispatchAgent, fireMessage, getBaseName, getJob, getName, getNames, getProperty, getUniqueName, goOffline, goOnline, isOnline, onDestruction, removeListener, run, setBase, version, wipeClean

Methods inherited from class java.lang.Object

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

Methods inherited from interface drm.core.Contributor

getName

Constructor Detail

Node

public Node(java.util.Properties cfg)

Calls super constructor. The additional configuration parameters understood by the class are the following:

• Every property that starts with "node" gives the address of another living node in the form host:port.
• If the property spy is "true" (case sensitive) then when exchanging information with other nodes this will not publis its own descriptor. Thus this will be an observer of the collective but not a contributor. The default is false.

Method Detail

launch

public IRequest launch(java.lang.String method,
                       IAgent agent,
                       java.lang.Object par)

Adds implementation of launch method "RANDOM". Launches an agent to an indirectly specified location. If no peers of the agent are present (a peer of a thread is a thread from the same job) at the local host then launches the agent locally ("local" type) otherwise launches to a random base ("random" type or "random local" type if the random base was the local base).

Overrides:

launch in class Base

Parameters:

method - If "RANDOM", runs the above algorithm otherwise propagates call to superclass.

par - ignored

Returns:

The request. The getInfo method there knows two kinds of queries: "type" which returns the type as desribed above in String format and "address" which returns the address of the launched agent (type Address) if status is DONE, otherwise null.

getContribution

public ContributionBox getContribution(java.lang.String nodeName)

Description copied from interface: IDRM

Returns the contribution that belongs to the given node name. If the contribution of the given node is not known, returns null.

Specified by:

getContribution in interface IDRM

getNewestContribution

public ContributionBox getNewestContribution()

Description copied from interface: IDRM

Returns the most up-to-date contribution. Returns null if the node has never communicated with anyone.

Specified by:

getNewestContribution in interface IDRM

getContributions

public java.util.List getContributions()

Description copied from interface: IDRM

Returns all known contributions in the DRM collective. Dynamic type of objects is ContributionBox, and the type of the contribution field is NodeContribution. Returned list might be empty, but it's never null.

Specified by:

getContributions in interface IDRM

Following copied from interface: drm.core.IDRM

See Also:

Collective.getContributions()

close

public void close()

Calls super implementation and after that closes the collective.

Overrides:

close in class Base

getFirewall

public Base.Firewall getFirewall()

Description copied from class: Base

This method should return the firewall that is given to the agents. It is useful to put it here because extending classes can extend the firewall with new functionality that agents can check for.

Overrides:

getFirewall in class Base

handleMessage

public boolean handleMessage(Message m,
                             java.lang.Object object)

Handles message type "collectiveUpdate-"+getJob(). In fact only forwards it to the collective.

Overrides:

handleMessage in class Base

Following copied from interface: drm.agentbase.IAgent

Parameters:

m - The message to handle.

object - The object that is wrapped in the message. If null then there is no binary content or it is not a serialized object (in which case it can be read using Message.getBinary()).

Returns:

If the message could be handled succesfully (i.e. it was known to the implementation and no errors occured) returns true, otherwise false.

See Also:

Message.setReply(Object), IBase.fireMessage(Message)

getType

public java.lang.String getType()

Returns "Node".

Overrides:

getType in class Base

onArrival

public void onArrival(Address from,
                      Address to)

Connects to the DRM collective. It is called by the Base when going online. It is not supposed to be called by users, it has to be public because it is an interface function.

Overrides:

onArrival in class Base

Following copied from interface: drm.agentbase.IAgent

Parameters:

from - The address of the base from which the agent was sent. If the agent has never been on any base it is null.

to - The address of the local base at the time of the arrival. It is not guaranteed to remain valid trough the lifetime of the agent. If the agent has never been on a base it is null.

See Also:

IAgent.setBase(IBase)

collectiveUpdated

public void collectiveUpdated(ContributionBox peer)

Stores the peer, and performs new commands.

Specified by:

collectiveUpdated in interface Observer

getPeerAddresses

public Address[] getPeerAddresses()

Returns always null. Implements required functionality via calling addPeerAddress instead, thus through a side effect.

Specified by:

getPeerAddresses in interface Observer

See Also:

Collective.addPeerAddress(Address)

fireMessage

public IRequest fireMessage(Address recipient,
                            java.lang.String type,
                            java.lang.Object content)

Description copied from interface: Observer

The observer must provide this method to allow requesting information.

Specified by:

fireMessage in interface Observer

getContribution

public java.lang.Object getContribution()

Description copied from interface: Contributor

The contributor has to return its contribution to the common repository when asked through this method.

Specified by:

getContribution in interface Contributor

getCommands

public java.util.Set getCommands()

Description copied from interface: Controller

The controller has to return the new commands it intends to execute in the collective. The type of the commands is collective-specific, but command objects have to implement equals and also hashCode to allow storage of commands in hashtables. It is also necessary that every command is unique, ie it does not equal any other command invoked at some other time (maybe by the same user).

Specified by:

getCommands in interface Controller

addNodes

public void addNodes(java.util.Properties cfg)

Adds the peers defined in cfg to the default peer list of the collective. Initializes peers from the properties starting with "base" or "node". The format of the property value should be host[:port]. If no port is given then the one defined in cfg is used, or 10101 as default.

invokeCommand

public void invokeCommand(NodeCommand command)

Invokes the command on the DRM.

invokeCommandLocally

public void invokeCommandLocally(NodeCommand command)

Invokes the command only on this local node.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object