diff --git a/cs656/lab2/src/Makefile b/cs656/lab2/src/Makefile
new file mode 100644
index 0000000..511c06b
--- /dev/null
+++ b/cs656/lab2/src/Makefile
@@ -0,0 +1,6 @@
+
+all:
+	javac *.java
+
+clean:
+	-rm -f *.class *~
diff --git a/cs656/lab2/src/PresenceServiceImpl.java b/cs656/lab2/src/PresenceServiceImpl.java
index 851526d..e892fdd 100644
--- a/cs656/lab2/src/PresenceServiceImpl.java
+++ b/cs656/lab2/src/PresenceServiceImpl.java
@@ -1,9 +1,13 @@
+
+import java.util.HashMap;
 import java.rmi.registry.LocateRegistry;
 import java.rmi.registry.Registry;
 import java.rmi.server.UnicastRemoteObject;
 
 public class PresenceServiceImpl implements PresenceService
 {
+    private HashMap<String, RegistrationInfo> myRegisteredUsers;
+
 	public PresenceServiceImpl()
 	{
 		super();
@@ -11,20 +15,23 @@ public class PresenceServiceImpl implements PresenceService
 
     public void register(RegistrationInfo reg)
 	{
+	    if (!myRegisteredUsers.containsKey(reg.getUserName()))
+            myRegisteredUsers.put(reg.getUserName(), reg);
 	}
 
     public void unregister(String userName)
 	{
+	    myRegisteredUsers.remove(userName);
 	}
 
     public RegistrationInfo lookup(String name)
 	{
-		return null;
+	    return myRegisteredUsers.get(name);
 	}
 
     public RegistrationInfo[] listRegisteredUsers()
 	{
-		return null;
+		return myRegisteredUsers.values().toArray(new RegistrationInfo[0]);
 	}
 
 	public static void main(String[] args)