/***************************************************************************
* *
* Node.java *
* ------------------- *
* date : 16.08.2004 *
* copyright : (C) 2004-2008 Distributed and *
* Mobile Systems Group *
* Lehrstuhl fuer Praktische Informatik *
* Universitaet Bamberg *
* http://www.uni-bamberg.de/pi/ *
* email : sven.kaffille@uni-bamberg.de *
* karsten.loesing@uni-bamberg.de *
* *
* *
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* A copy of the license can be found in the license.txt file supplied *
* with this software or at: http://www.gnu.org/copyleft/gpl.html *
* *
***************************************************************************/
package de.uniba.wiai.lspi.chord.com;
import java.util.List;
import java.util.Set;
import de.uniba.wiai.lspi.chord.data.ID;
import de.uniba.wiai.lspi.chord.data.URL;
import de.uniba.wiai.lspi.chord.service.NotifyCallback;
/**
* Provides methods which remote nodes can invoke.
*
* @author Sven Kaffille, Karsten Loesing
* @version 1.0.5
*/
/*
* 21.03.2006 changed by sven. Node needs not to be Serializable as no instances
* of it are supposed to being serialized.
*/
public abstract class Node implements Comparable<Node> {
@Override
public final boolean equals(Object arg0) {
if (arg0 == null || !(arg0 instanceof Node)) {
return false;
}
return ((Node) arg0).nodeID.equals(this.nodeID);
}
@Override
public final int hashCode() {
return this.nodeID.hashCode();
}
@Override
public String toString() {
String id = null;
if (this.nodeID != null) {
id = this.nodeID.toString();
}
String url = "null";
if (this.nodeURL != null) {
url = this.nodeURL.toString();
}
return "Node[type=" + this.getClass().getSimpleName() + ", id="
+ id + ", url=" + url + "]";
}
@Override
public int compareTo(final Node node) {
return this.getNodeID().compareTo(node.getNodeID());
}
/**
* This is the id of this node. It has to be set by every implementation of
* this class!
*/
protected ID nodeID;
/**
* This is the url of this node. It has to be set by every implementation of
* this class!
*/
protected URL nodeURL;
protected NotifyCallback notifyCallback;
/**
* Returns the ID of a node. Is invoked by remote nodes which do not know
* the ID of this node, yet. After invocation, the nodeID is remembered by
* the remote node, s.t. future invocations of getNodeID are unnecessary.
*
* @return ID of a node.
* @throws CommunicationException
* If something goes wrong when contacting the node.
*/
public final ID getNodeID() {
return this.nodeID;
}
/**
*
* @return
*/
public final URL getNodeURL() {
return this.nodeURL;
}
public final NotifyCallback getNotifyCallback () {
return this.notifyCallback;
}
/**
* Returns the Chord node which is responsible for the given key.
*
* @param key
* Key for which the successor is searched for.
* @return Responsible node.
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract Node findSuccessor(ID key) throws CommunicationException;
/**
* Requests this node's predecessor in result[0] and successor list in
* result[1..length-1]. This method is invoked by another node which thinks
* it is this node's predecessor.
*
* @param potentialPredecessor
* @return A list containing the predecessor at first position of the list
* and the successors in the rest of the list.
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract List<Node> notify(Node potentialPredecessor)
throws CommunicationException;
/**
* Requests this node's predecessor, successor list and entries.
*
* @param potentialPredecessor
* Remote node which invokes this method
* @return References to predecessor and successors and the entries this
* node will be responsible for.
* @throws CommunicationException
*/
public abstract RefsAndEntries notifyAndCopyEntries(
Node potentialPredecessor) throws CommunicationException;
/**
* Requests a sign of live. This method is invoked by another node which
* thinks it is this node's successor.
*
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract void ping() throws CommunicationException;
/**
* Stores the given object under the given ID.
*
* @param entryToInsert
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract void insertEntry(Entry entryToInsert)
throws CommunicationException;
/**
* Inserts replicates of the given entries.
*
* @param entries
* The entries that are replicated.
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*
*/
public abstract void insertReplicas(Set<Entry> entries)
throws CommunicationException;
/**
* Removes the given object from the list stored under the given ID.
*
* @param entryToRemove
* The entry to remove from the dht.
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract void removeEntry(Entry entryToRemove)
throws CommunicationException;
/**
* Removes replicates of the given entries.
*
* @param sendingNode
* ID of sending node; if entriesToRemove is empty, all replicas
* with ID smaller than the sending node's ID are removed
* @param replicasToRemove
* Replicas to remove; if empty, all replicas with ID smaller
* than the sending node's ID are removed
*
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract void removeReplicas(ID sendingNode,
Set<Entry> replicasToRemove) throws CommunicationException;
/**
* Returns all entries stored under the given ID.
*
* @param id
* @return A {@link Set} of entries associated with <code>id</code>.
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract Set<Entry> retrieveEntries(ID id)
throws CommunicationException;
/**
* Inform a node that its predecessor leaves the network.
*
* @param predecessor
* @throws CommunicationException
* Thrown if an unresolvable communication failure occurs.
*/
public abstract void leavesNetwork(Node predecessor)
throws CommunicationException;
/**
* Closes the connection to the node.
*/
public abstract void disconnect();
/**
* @param nodeID
* the nodeID to set
*/
protected final void setNodeID(ID nodeID) {
this.nodeID = nodeID;
}
/**
* @param nodeURL
* the nodeURL to set
*/
protected final void setNodeURL(URL nodeURL) {
this.nodeURL = nodeURL;
}
public final void setNotifyCallback(final NotifyCallback callback) {
this.notifyCallback = callback;
}
public final void clearCallback() {
this.notifyCallback = null;
}
public abstract void broadcast (Broadcast info)
throws CommunicationException;
}