org.planx.xmlstore.routing.operation
Class DataLookupOperation

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

All Implemented Interfaces:

Receiver

public class DataLookupOperation
extends NodeLookupOperation

Looks up the specified identifier and returns the value associated with it. It is not checked if the data is available in the local IdentifierMap, so this should be checked before this operation is executed. The subclassing is merely for code reuse.

Field Summary

protected Serializable

value The found value or null if it has not been found.

Fields inherited from class org.planx.xmlstore.routing.operation.NodeLookupOperation

conf, error, id, local, lookupMessage, server, space

Constructor Summary

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

Method Summary

Object	execute() Starts the operation and returns when the operation is finished.
void	receive(Message incoming, int comm) Once a DataMessage is received the algorithm terminates.

Methods inherited from class org.planx.xmlstore.routing.operation.NodeLookupOperation

timeout

Methods inherited from class java.lang.Object

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

Field Detail

value

protected Serializable value

The found value or null if it has not been found.

Constructor Detail

DataLookupOperation

public DataLookupOperation(Configuration conf,
                           MessageServer server,
                           Space space,
                           Node local,
                           Identifier 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.

Overrides:

execute in class NodeLookupOperation

Returns:

The value associated with the key or null if no mapping with the specified key could be found.

Throws:

RoutingException - If the lookup operation timed out

IOException - If a network error occurred

receive

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

Once a DataMessage is received the algorithm terminates. If a NodeReplyMessage is received the algorithm continues as by the superclass.

Specified by:

receive in interface Receiver

Overrides:

receive in class NodeLookupOperation

Throws:

IOException - if an I/O error occurs