diff --git a/core/api/src/main/java/org/onosproject/ui/model/ServiceBundle.java b/core/api/src/main/java/org/onosproject/ui/model/ServiceBundle.java
new file mode 100644
index 0000000..61cf721
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/ui/model/ServiceBundle.java
@@ -0,0 +1,87 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.ui.model;
+
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.flow.FlowRuleService;
+import org.onosproject.net.host.HostService;
+import org.onosproject.net.intent.IntentService;
+import org.onosproject.net.link.LinkService;
+import org.onosproject.net.region.RegionService;
+
+/**
+ * A bundle of services to pass to elements that might need a reference to them.
+ */
+public interface ServiceBundle {
+    /**
+     * Reference to a cluster service implementation.
+     *
+     * @return cluster service
+     */
+    ClusterService cluster();
+
+    /**
+     * Reference to a mastership service implementation.
+     *
+     * @return mastership service
+     */
+    MastershipService mastership();
+
+    /**
+     * Reference to a region service implementation.
+     *
+     * @return region service
+     */
+    RegionService region();
+
+    /**
+     * Reference to a device service implementation.
+     *
+     * @return device service
+     */
+    DeviceService device();
+
+    /**
+     * Reference to a link service implementation.
+     *
+     * @return link service
+     */
+    LinkService link();
+
+    /**
+     * Reference to a host service implementation.
+     *
+     * @return host service
+     */
+    HostService host();
+
+    /**
+     * Reference to a intent service implementation.
+     *
+     * @return intent service
+     */
+    IntentService intent();
+
+    /**
+     * Reference to a flow service implementation.
+     *
+     * @return flow service
+     */
+    FlowRuleService flow();
+}
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiCluster.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiCluster.java
index a5de405..40de28c 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiCluster.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiCluster.java
@@ -28,12 +28,14 @@
  */
 class UiCluster extends UiElement {
 
+    private static final String DEFAULT_CLUSTER_ID = "CLUSTER-0";
+
     private final List<UiClusterMember> members = new ArrayList<>();
     private final Map<NodeId, UiClusterMember> lookup = new HashMap<>();
 
     @Override
     public String toString() {
-        return String.valueOf(members.size()) + "-member cluster";
+        return String.valueOf(size()) + "-member cluster";
     }
 
     /**
@@ -65,6 +67,16 @@
     }
 
     /**
+     * Removes the given member from the cluster.
+     *
+     * @param member member to remove
+     */
+    public void remove(UiClusterMember member) {
+        members.remove(member);
+        lookup.remove(member.id());
+    }
+
+    /**
      * Returns the number of members in the cluster.
      *
      * @return number of members
@@ -72,4 +84,9 @@
     public int size() {
         return members.size();
     }
+
+    @Override
+    public String idAsString() {
+        return DEFAULT_CLUSTER_ID;
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java
index f89a9ae..1cc9234 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java
@@ -16,9 +16,12 @@
 
 package org.onosproject.ui.model.topo;
 
+import org.onlab.packet.IpAddress;
 import org.onosproject.cluster.ControllerNode;
 import org.onosproject.cluster.NodeId;
 
+import static org.onosproject.cluster.ControllerNode.State.INACTIVE;
+
 /**
  * Represents an individual member of the cluster (ONOS instance).
  */
@@ -26,6 +29,9 @@
 
     private final ControllerNode cnode;
 
+    private int deviceCount = 0;
+    private ControllerNode.State state = INACTIVE;
+
     /**
      * Constructs a cluster member, with a reference to the specified
      * controller node instance.
@@ -36,13 +42,33 @@
         this.cnode = cnode;
     }
 
+    @Override
+    public String toString() {
+        return "UiClusterMember{" + cnode +
+                ", online=" + isOnline() +
+                ", ready=" + isReady() +
+                ", #devices=" + deviceCount +
+                "}";
+    }
+
+
     /**
-     * Updates the information about this cluster member.
+     * Sets the state of this cluster member.
      *
-     * @param cnode underlying controller node
+     * @param state the state
      */
-    public void update(ControllerNode cnode) {
-        // TODO: update our information cache appropriately
+    public void setState(ControllerNode.State state) {
+        this.state = state;
+    }
+
+
+    /**
+     * Sets the number of devices for which this cluster member is master.
+     *
+     * @param deviceCount number of devices
+     */
+    public void setDeviceCount(int deviceCount) {
+        this.deviceCount = deviceCount;
     }
 
     /**
@@ -53,4 +79,45 @@
     public NodeId id() {
         return cnode.id();
     }
+
+    /**
+     * Returns the IP address of the cluster member.
+     *
+     * @return the IP address
+     */
+    public IpAddress ip() {
+        return cnode.ip();
+    }
+
+    /**
+     * Returns true if this cluster member is online (active).
+     *
+     * @return true if online, false otherwise
+     */
+    public boolean isOnline() {
+        return state.isActive();
+    }
+
+    /**
+     * Returns true if this cluster member is considered ready.
+     *
+     * @return true if ready, false otherwise
+     */
+    public boolean isReady() {
+        return state.isReady();
+    }
+
+    /**
+     * Returns the number of devices for which this cluster member is master.
+     *
+     * @return number of devices for which this member is master
+     */
+    public int deviceCount() {
+        return deviceCount;
+    }
+
+    @Override
+    public String idAsString() {
+        return id().toString();
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java
index 78f9d47..88d86d0 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java
@@ -17,6 +17,7 @@
 package org.onosproject.ui.model.topo;
 
 import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
 
 /**
  * Represents a device.
@@ -29,4 +30,18 @@
     protected void destroy() {
         device = null;
     }
+
+    /**
+     * Returns the identity of the device.
+     *
+     * @return device ID
+     */
+    public DeviceId id() {
+        return device.id();
+    }
+
+    @Override
+    public String idAsString() {
+        return id().toString();
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiElement.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiElement.java
index 5e6144d..f0c2684 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiElement.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiElement.java
@@ -19,7 +19,7 @@
 /**
  * Abstract base class of all elements in the UI topology model.
  */
-public class UiElement {
+public abstract class UiElement {
 
     /**
      * Removes all external references, and prepares the instance for
@@ -28,4 +28,11 @@
     protected void destroy() {
         // does nothing
     }
+
+    /**
+     * Returns a string representation of the element identifier.
+     *
+     * @return the element unique identifier
+     */
+    public abstract String idAsString();
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiHost.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiHost.java
index 933e469..9a9e24a 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiHost.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiHost.java
@@ -17,6 +17,7 @@
 package org.onosproject.ui.model.topo;
 
 import org.onosproject.net.Host;
+import org.onosproject.net.HostId;
 
 /**
  * Represents an end-station host.
@@ -29,4 +30,18 @@
     protected void destroy() {
         host = null;
     }
+
+    /**
+     * Returns the identity of the host.
+     *
+     * @return host ID
+     */
+    public HostId id() {
+        return host.id();
+    }
+
+    @Override
+    public String idAsString() {
+        return id().toString();
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiLink.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiLink.java
index f45a630..99d6144 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiLink.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiLink.java
@@ -54,4 +54,10 @@
             children = null;
         }
     }
+
+    @Override
+    public String idAsString() {
+        // TODO
+        return null;
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegion.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegion.java
index 9a3d6fb..488c37b 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegion.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegion.java
@@ -17,6 +17,7 @@
 package org.onosproject.ui.model.topo;
 
 import org.onosproject.net.region.Region;
+import org.onosproject.net.region.RegionId;
 
 import java.util.Set;
 import java.util.TreeSet;
@@ -46,4 +47,17 @@
         region = null;
     }
 
+    /**
+     * Returns the identity of the region.
+     *
+     * @return region ID
+     */
+    public RegionId id() {
+        return region.id();
+    }
+
+    @Override
+    public String idAsString() {
+        return id().toString();
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiTopology.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiTopology.java
index 898c8eb..a8b5b06 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiTopology.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiTopology.java
@@ -28,6 +28,8 @@
  */
 public class UiTopology extends UiElement {
 
+    private static final String DEFAULT_TOPOLOGY_ID = "TOPOLOGY-0";
+
     private static final Logger log = LoggerFactory.getLogger(UiTopology.class);
 
     private final UiCluster uiCluster = new UiCluster();
@@ -69,6 +71,15 @@
     }
 
     /**
+     * Removes the given cluster member from the topology model.
+     *
+     * @param member cluster member to remove
+     */
+    public void remove(UiClusterMember member) {
+        uiCluster.remove(member);
+    }
+
+    /**
      * Returns the number of members in the cluster.
      *
      * @return number of cluster members
@@ -85,4 +96,9 @@
     public int regionCount() {
         return uiRegions.size();
     }
+
+    @Override
+    public String idAsString() {
+        return DEFAULT_TOPOLOGY_ID;
+    }
 }