Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventImpl.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventImpl.java	(revision 1469221)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventImpl.java	(working copy)
@@ -22,12 +22,13 @@
 import java.util.Map;
 
 import javax.jcr.RepositoryException;
-import javax.jcr.observation.Event;
 
+import org.apache.jackrabbit.api.observation.JackrabbitEvent;
+
 /**
  * TODO document
  */
-public class EventImpl implements Event {
+public class EventImpl implements JackrabbitEvent {
     private final int type;
     private final String path;
     private final String userID;
@@ -35,8 +36,9 @@
     private final Map<?, ?> info;
     private final long date;
     private final String userData;
+    private final boolean external;
 
-    public EventImpl(int type, String path, String userID, String identifier, Map<?, ?> info, long date, String userData) {
+    public EventImpl(int type, String path, String userID, String identifier, Map<?, ?> info, long date, String userData, boolean external) {
         this.type = type;
         this.path = path;
         this.userID = userID;
@@ -44,6 +46,7 @@
         this.info = info == null ? Collections.emptyMap() : info;
         this.date = date;
         this.userData = userData;
+        this.external = external;
     }
 
     @Override
@@ -81,7 +84,14 @@
         return date;
     }
 
+    //-------------------------< JackrabbitEvent >------------------------------
+
     @Override
+    public boolean isExternal() {
+        return external;
+    }
+
+    @Override
     public final boolean equals(Object other) {
         if (this == other) {
             return true;
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueReader.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueReader.java	(revision 1469221)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueReader.java	(working copy)
@@ -21,6 +21,7 @@
 
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.DATE;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.EVENTS_PATH;
+import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.INSTANCE_ID;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.PATH;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.TYPE;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.USER_DATA;
@@ -46,6 +47,7 @@
 public class EventQueueReader {
     private final Root root;
     private final NamePathMapper namePathMapper;
+    private final String instanceId = EventQueueWriterProvider.INSTANCE_ID;
 
     private Tree bundles;
     private long nextBundleId = EventQueueWriterProvider.BUNDLE_ID.get();
@@ -100,7 +102,8 @@
         String userId = getString(event.getChild(id), USER_ID);
         long date = getLong(event, DATE, 0);
         String userData = getString(event.getChild(id), USER_DATA);
-        return new EventImpl(type, path, userId, id, Collections.emptyMap(), date, userData);
+        boolean external = !instanceId.equals(getString(event.getParent(), INSTANCE_ID));
+        return new EventImpl(type, path, userId, id, Collections.emptyMap(), date, userData, external);
     }
 
     private String getJcrPath(Tree event) {
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueWriter.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueWriter.java	(revision 1469221)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueWriter.java	(working copy)
@@ -30,6 +30,7 @@
 import static org.apache.jackrabbit.JcrConstants.JCR_UUID;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.DATE;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.DEEP;
+import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.INSTANCE_ID;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.NODE_TYPES;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.NO_LOCAL;
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.PATH;
@@ -238,10 +239,11 @@
 
         private long eventId;
 
-        public EventRecorder(NodeBuilder eventQueue, Iterable<ListenerSpec> listenerSpecs) {
+        public EventRecorder(NodeBuilder eventQueue, Iterable<ListenerSpec> listenerSpecs, String instanceId) {
             this.eventQueue = eventQueue;
             this.listenerSpecs = listenerSpecs;
             this.date = System.currentTimeMillis();
+            this.eventQueue.setProperty(INSTANCE_ID, instanceId);
         }
 
         private void recordEvent(int type, String path, String identifier, String[] associatedParentTypes) {
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueWriterProvider.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueWriterProvider.java	(revision 1469221)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/EventQueueWriterProvider.java	(working copy)
@@ -25,6 +25,7 @@
 import static org.apache.jackrabbit.oak.plugins.observation2.ObservationConstants.REP_OBSERVATION;
 
 import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.atomic.AtomicLong;
 
 import com.google.common.collect.Sets;
@@ -44,6 +45,8 @@
  */
 public class EventQueueWriterProvider implements EditorProvider {
     public static final AtomicLong BUNDLE_ID = new AtomicLong();
+    // FIXME: does not work for multiple cluster nodes in single JVM
+    public static final String INSTANCE_ID = UUID.randomUUID().toString();
 
     @Override
     public Editor getRootEditor(NodeState before, NodeState after, NodeBuilder builder) {
@@ -57,7 +60,7 @@
             return DefaultEditor.INSTANCE;
         }
 
-        EventRecorder eventRecorder = new EventRecorder(queue, listenerSpecs);
+        EventRecorder eventRecorder = new EventRecorder(queue, listenerSpecs, INSTANCE_ID);
         return VisibleEditor.wrap(new EventQueueWriter(eventRecorder, "/", after));
     }
 
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/ObservationConstants.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/ObservationConstants.java	(revision 1469221)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation2/ObservationConstants.java	(working copy)
@@ -39,6 +39,7 @@
     String UUID = "uuid";
     String NODE_TYPES = "nodeTypes";
     String NO_LOCAL = "noLocal";
+    String INSTANCE_ID = "instanceId";
 
     String LISTENER_PATH = '/' + JCR_SYSTEM + '/' + REP_OBSERVATION + '/' + LISTENERS;
     String EVENTS_PATH = '/' + JCR_SYSTEM + '/' + REP_OBSERVATION + '/' + EVENTS;