org.planx.xmlstore.routing.operation
Class NodeLookupOperation

java.lang.Object
  org.planx.xmlstore.routing.operation.Operation
      org.planx.xmlstore.routing.operation.NodeLookupOperation

All Implemented Interfaces:

Receiver

Direct Known Subclasses:

DataLookupOperation

public class NodeLookupOperation
extends Operation
implements Receiver

Finds the K closest nodes to a specified identifier. The algorithm terminates when the operation has gotten responses from the K closest nodes it has seen. Nodes that fail to respond are removed from consideration.

Author:

Thomas Ambus

Field Summary

protected Configuration	conf
protected boolean	error
protected Identifier	id
protected Node	local
protected LookupMessage	lookupMessage Message sent to each peer.
protected MessageServer	server
protected Space	space

Constructor Summary

NodeLookupOperation(Configuration conf, MessageServer server, Space space, Node local, Identifier id)
Create a NodeLookupOperation for the specified id.

Method Summary

Object	execute() Starts the operation and returns when the operation is finished.
void	receive(Message incoming, int comm) Receives an incoming NodeReplyMessage.
void	timeout(int comm) A node does not respond or a packet was lost.

Methods inherited from class java.lang.Object

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

Field Detail

conf

protected Configuration conf

server

protected MessageServer server

space

protected Space space

local

protected Node local

id

protected Identifier id

error

protected boolean error

lookupMessage

protected LookupMessage lookupMessage

Message sent to each peer. Subclasses could change this field to send other kinds of lookup messages.

Constructor Detail

NodeLookupOperation

public NodeLookupOperation(Configuration conf,
                           MessageServer server,
                           Space space,
                           Node local,
                           Identifier id)

Create a NodeLookupOperation for the specified id.

Method Detail

execute

public Object execute()
               throws IOException,
                      RoutingException

Description copied from class: Operation

Starts the operation and returns when the operation is finished.

Specified by:

execute in class Operation

Returns:

A List containing the K closest nodes to the id provided in the constructor.

Throws:

RoutingException - If the lookup operation timed out

IOException - If a network error occurred

receive

public void receive(Message incoming,
                    int comm)
             throws IOException

Receives an incoming NodeReplyMessage.

Specified by:

receive in interface Receiver

Throws:

IOException - if an I/O error occurs

timeout

public void timeout(int comm)
             throws IOException

A node does not respond or a packet was lost.

Specified by:

timeout in interface Receiver

Throws:

IOException - if an I/O error occurs