Index: src/main/java/com/sun/enterprise/ee/cms/impl/base/ViewWindowImpl.java
===================================================================
--- src/main/java/com/sun/enterprise/ee/cms/impl/base/ViewWindowImpl.java	(revision 822)
+++ src/main/java/com/sun/enterprise/ee/cms/impl/base/ViewWindowImpl.java	(working copy)
@@ -66,6 +66,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Vector;
+import java.util.Collections;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -80,7 +81,7 @@
     static private Logger logger = GMSLogDomain.getLogger(GMSLogDomain.GMS_LOGGER);
     private static final int MAX_VIEWS = 100;  // 100 is some default.
     private static final List<GMSMember> EMPTY_GMS_MEMBER_LIST = new ArrayList<GMSMember>();
-    private final List<ArrayList<GMSMember>> views = new Vector<ArrayList<GMSMember>>();
+    private final List<List<GMSMember>> views = new Vector<List<GMSMember>>();
     private List<Signal> signals = new Vector<Signal>();
     private final List<String> currentCoreMembers = new ArrayList<String>();
     private final List<String> allCurrentMembers = new ArrayList<String>();
@@ -143,7 +144,7 @@
     private void newViewObserved(final EventPacket packet) {
         final GMSMember member = Utility.getGMSMember(packet.getSystemAdvertisement());
         synchronized (views) {
-            views.add(getMemberTokens(packet));
+            views.add(Collections.unmodifiableList(getMemberTokens(packet)));
             if (views.size() > MAX_VIEWS) {
                 views.remove(0);
             }
Index: src/main/java/com/sun/enterprise/ee/cms/core/GroupLeadershipNotificationSignal.java
===================================================================
--- src/main/java/com/sun/enterprise/ee/cms/core/GroupLeadershipNotificationSignal.java	(revision 822)
+++ src/main/java/com/sun/enterprise/ee/cms/core/GroupLeadershipNotificationSignal.java	(working copy)
@@ -48,14 +48,14 @@
  */
 public interface GroupLeadershipNotificationSignal extends Signal {
     /**
-     * provides a list of the previous view's snapshot at time signal arrives.
+     * provides a read-only list of the previous view's snapshot at time signal arrives.
      *
      * @return List containing the list of <code>GMSMember</code>s which are corresponding to the view
      */
     List<GMSMember> getPreviousView();
 
     /**
-     * provides a list of the current view's snapshot at time signal arrives.
+     * provides a read-only list of the current view's snapshot at time signal arrives.
      *
      * @return List containing the list of <code>GMSMember</code>s which are corresponding to the view
      */