Contact-Based Routing (CBR)

src/routing/CBR.java

@@ -0,0 +1,179 @@
+/* CBRRouter router
+ * CBRRouter.java
+ *
+ * @Author Sujata Pal
+ *
+ * Created on August 02, 2014
+ * Paper name: "Contact-Based Routing in DTNs" published in
+ * ACM IMCOM 2015
+ */
+
+package routing;
+
+import core.Connection;
+import core.DTNHost;
+import core.Message;
+import core.Settings;
+import core.SimClock;
+import core.SimScenario;
+import java.util.ArrayList;
+import java.util.List;
+import util.Tuple;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+import java.util.*;
+import core.*;
+import core.ConnectionListener;
+
+
+public class CBRRouter extends ActiveRouter {
+
+
+    protected Map<Integer, ArrayList<Integer>> nodesInf;
+    protected ArrayList<Integer> nodeConnections;
+
+
+    /**
+     * Constructor. Creates a new message router based on the settings in
+     * the given Settings object.
+     * @param s The settings object
+     */
+    public CBRRouter(Settings s) {
+        super(s);
+        init();
+
+    }
+
+    /**
+     * Copy constructor.
+     * @param r The router prototype where setting values are copied from
+     */
+    protected CBRRouter(CBRRouter r) {
+        super(r);
+        init();
+
+    }
+
+    private void init() {
+
+        this.nodesInf = new TreeMap<Integer, ArrayList<Integer>>();
+        this.nodeConnections = new ArrayList<Integer> ();
+     }
+
+     @Override
+    public void changedConnection(Connection con) {
+        if (con.isUp()) {
+
+
+                DTNHost self = this.getHost();
+                DTNHost otherNode = con.getOtherNode(self);
+
+
+                if (! this.nodesInf.containsKey(otherNode.getAddress())) {
+                    ArrayList<Integer> items = new ArrayList<Integer>();
+                    items.add(1);
+
+                    this.nodesInf.put(otherNode.getAddress(), items);
+                }
+
+                if (this.nodesInf.containsKey(otherNode.getAddress())) {     
+                    ArrayList<Integer> items = this.nodesInf.get(otherNode.getAddress());
+
+                    items.set(0, items.get(0) + 1);
+
+                    this.nodesInf.put(otherNode.getAddress(), items);
+                }
+        }
+    }
+
+
+
+    @Override
+    protected int checkReceiving(Message m, DTNHost from) {
+        int recvCheck = super.checkReceiving(m, from);
+
+        if (recvCheck == RCV_OK) {
+            /* don't accept a message that has already traversed this node */
+            if (m.getHops().contains(getHost())) {
+                recvCheck = DENIED_OLD;
+            }
+        }
+
+        return recvCheck;
+    }
+
+    @Override
+    public void update() {
+        super.update();
+
+        if (isTransferring() || !canStartTransfer()) {
+            return;
+        }
+
+        if (exchangeDeliverableMessages() != null) {
+            return;
+        }
+
+        tryAllMessagesToAllConnections();
+    }
+
+
+    @Override
+    protected Connection tryMessagesToConnections(List<Message> messages,
+            List<Connection> connections) {
+
+        for (Message m : messages) {
+
+            DTNHost msgDst = m.getTo();
+            DTNHost self = this.getHost();
+            int maxEnc = 0;
+            DTNHost maxEncHost;
+            Connection conEnc = connections.get(0);
+            int k=0;
+            for (int i=0, n=connections.size(); i<n; i++) {
+                Connection con = connections.get(i);
+                DTNHost otherNode = con.getOtherNode(self);
+
+                CBRRouter otherRouter = (CBRRouter) otherNode.getRouter();
+
+
+                //if other end of the connection contain (meet with the) destination node of the current msg
+                if (otherRouter.nodesInf.containsKey(msgDst.getAddress())) {
+                    ArrayList<Integer> items = otherRouter.nodesInf.get(msgDst.getAddress());                   
+
+                    int encounter = items.get(0);
+                    if (encounter > maxEnc) {
+                        maxEnc = encounter;
+                        maxEncHost = otherNode;
+                        conEnc = con;
+                    }
+                }
+
+                Random r = new Random();
+                k = r.nextInt(n);
+
+            }
+            if(maxEnc == 0) {   
+                conEnc = connections.get(k);
+            }
+            int retVal = startTransfer(m, conEnc);
+            if (retVal == RCV_OK) {
+                return conEnc;    // accepted a message, don't try others
+            }
+            else if (retVal > 0) {
+                return null; // should try later -> don't bother trying others
+            }
+        }
+
+        return null;
+    }
+
+
+
+    @Override
+    public CBRRouter replicate() {
+        return new CBRRouter(this);
+    }
+
+}