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/*
* Copyright (C) 2015 SDN-WISE
*
* 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 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
package com.github.sdnwiselab.sdnwise.topology;
import com.github.sdnwiselab.sdnwise.packet.ReportPacket;
import com.github.sdnwiselab.sdnwise.util.NodeAddress;
import java.util.HashSet;
import java.util.Observable;
import java.util.Set;
import org.graphstream.graph.Edge;
import org.graphstream.graph.Graph;
import org.graphstream.graph.Node;
import org.graphstream.graph.implementations.MultiGraph;
/**
* This class holds a org.graphstream.graph.Graph object which represent the
* topology of the wireless sensor network. The method updateMap is invoked when
* a message with topology updates is sent to the controller.
*
* @author Sebastiano Milardo
* @version 0.1
*/
public class NetworkGraph extends Observable {
final Graph graph;
private long lastModification;
private final int timeout;
final int rssiResolution;
private long lastCheck;
/**
* This constructor returns the NetworkGraph object. It requires a time to
* live for each node in the network and a value representing the RSSI
* resolution in order to consider a change of the RSSI value a change in
* the network.
*
* @param timeout the time to live for a node in seconds
* @param rssiResolution the RSSI resolution
*/
public NetworkGraph(int timeout, int rssiResolution) {
this.graph = new MultiGraph("SDN-WISE Network");
this.lastModification = Long.MIN_VALUE;
this.rssiResolution = rssiResolution;
this.timeout = timeout;
this.lastCheck = System.currentTimeMillis();
graph.setAutoCreate(true);
graph.setStrict(false);
}
/**
* Returns the last time instant when the NetworkGraph was updated.
*
* @return a long representing the last time instant when the NetworkGraph
* was updated
*/
public final synchronized long getLastModification() {
return lastModification;
}
/**
* This method gets the Graph contained in the NetworkGraph
*
* @return returns a Graph object
*/
public Graph getGraph() {
return graph;
}
final boolean checkConsistency(long now) {
boolean modified = false;
if (now - lastCheck > (timeout * 1000L)) {
lastCheck = now;
for (Node n : graph) {
if (n.getAttribute("lastSeen", Long.class) != null) {
if (!isAlive(timeout, (long) n.getNumber("lastSeen"), now)) {
removeNode(n);
modified = true;
}
}
}
}
return modified;
}
/**
* This method is invoked when a message with topology updates is received
* by the controller. It updates the network topology according to the
* message and checks if all the nodes in the network are still alive.
*
* @param packet the NetworkPacket received
*/
public final synchronized void updateMap(ReportPacket packet) {
long now = System.currentTimeMillis();
boolean modified = checkConsistency(now);
int netId = packet.getNetId();
int batt = packet.getBatt();
String nodeId = packet.getSrc().toString();
String fullNodeId = netId + "." + nodeId;
NodeAddress addr = packet.getSrc();
Node node = getNode(fullNodeId);
if (node == null) {
node = addNode(fullNodeId);
setupNode(node, batt, now, netId, addr);
for (int i = 0; i < packet.getNeigh(); i++) {
NodeAddress otheraddr = packet.getNeighbourAddress(i);
String other = netId + "." + otheraddr.toString();
if (getNode(other) == null) {
Node tmp = addNode(other);
setupNode(tmp, 0, now, netId, otheraddr);
}
int newLen = 255 - packet.getNeighbourWeight(i);
String edgeId = other + "-" + fullNodeId;
Edge edge = addEdge(edgeId, other, node.getId(), true);
setupEdge(edge, newLen);
}
modified = true;
} else {
updateNode(node, batt, now);
Set oldEdges = new HashSet<>();
for (Edge e : node.getEnteringEdgeSet()) {
oldEdges.add(e);
}
for (int i = 0; i < packet.getNeigh(); i++) {
NodeAddress otheraddr = packet.getNeighbourAddress(i);
String other = netId + "." + otheraddr.toString();
if (getNode(other) == null) {
Node tmp = addNode(other);
setupNode(tmp, 0, now, netId, otheraddr);
}
int newLen = 255 - packet.getNeighbourWeight(i);
String edgeId = other + "-" + fullNodeId;
Edge edge = getEdge(edgeId);
if (edge != null) {
oldEdges.remove(edge);
int oldLen = edge.getAttribute("length");
if (Math.abs(oldLen - newLen) > rssiResolution) {
updateEdge(edge, newLen);
modified = true;
}
} else {
Edge tmp = addEdge(edgeId, other, node.getId(), true);
setupEdge(tmp, newLen);
modified = true;
}
}
if (!oldEdges.isEmpty()) {
for (Edge e : oldEdges) {
removeEdge(e);
}
modified = true;
}
}
if (modified) {
lastModification++;
setChanged();
notifyObservers();
}
}
final boolean isAlive(long threashold, long lastSeen, long now) {
return ((now - lastSeen) < threashold * 1000);
}
void setupNode(Node node, int batt, long now, int netId, NodeAddress addr) {
node.addAttribute("battery", batt);
node.addAttribute("lastSeen", now);
node.addAttribute("netId", netId);
node.addAttribute("nodeAddress", addr);
}
void updateNode(Node node, int batt, long now) {
node.addAttribute("battery", batt);
node.addAttribute("lastSeen", now);
}
void setupEdge(Edge edge, int newLen) {
edge.addAttribute("length", newLen);
}
void updateEdge(Edge edge, int newLen) {
edge.addAttribute("length", newLen);
}
T addNode(String id) {
return graph.addNode(id);
}
T addEdge(String id, String from, String to,
boolean directed) {
return graph.addEdge(id, from, to, directed);
}
T removeEdge(Edge edge) {
return graph.removeEdge(edge);
}
T removeNode(Node node) {
return graph.removeNode(node);
}
/**
* Getter Method to obtain a Node of Graph.
*
* @param the type of node in the graph.
* @param id string id value to get a Node.
* @return
*/
public T getNode(String id) {
return graph.getNode(id);
}
/**
* Getter Method to obtain an Edge of Graph.
*
* @param the type of edge in the graph.
* @param id string id value to get an Edge.
* @return
*/
public T getEdge(String id) {
return graph.getEdge(id);
}
}
