diff --git a/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetrics.java b/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetrics.java
index 38366b6..cfc88b8 100644
--- a/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetrics.java
+++ b/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetrics.java
@@ -5,8 +5,6 @@
 import java.util.LinkedList;
 import java.util.List;
 
-import com.codahale.metrics.Gauge;
-import com.codahale.metrics.Meter;
 import com.google.common.collect.ImmutableList;
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
@@ -14,8 +12,7 @@
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.apache.felix.scr.annotations.Service;
-import org.onlab.metrics.MetricsComponent;
-import org.onlab.metrics.MetricsFeature;
+import org.onlab.metrics.EventMetric;
 import org.onlab.metrics.MetricsService;
 import org.onlab.onos.net.intent.IntentEvent;
 import org.onlab.onos.net.intent.IntentListener;
@@ -33,56 +30,32 @@
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected IntentService intentService;
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected MetricsService metricsService;
+
     private LinkedList<IntentEvent> lastEvents = new LinkedList<>();
     private static final int LAST_EVENTS_MAX_N = 100;
 
     //
     // Metrics
     //
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected MetricsService metricsService;
-    //
     private static final String COMPONENT_NAME = "Intent";
     private static final String FEATURE_SUBMITTED_NAME = "Submitted";
     private static final String FEATURE_INSTALLED_NAME = "Installed";
     private static final String FEATURE_WITHDRAW_REQUESTED_NAME =
         "WithdrawRequested";
     private static final String FEATURE_WITHDRAWN_NAME = "Withdrawn";
-    private static final String GAUGE_TIMESTAMP_NAME = "Timestamp.EpochMs";
-    private static final String METER_RATE_NAME = "Rate";
     //
-    private MetricsComponent metricsComponent;
-    private MetricsFeature metricsFeatureSubmitted;
-    private MetricsFeature metricsFeatureInstalled;
-    private MetricsFeature metricsFeatureWithdrawRequested;
-    private MetricsFeature metricsFeatureWithdrawn;
+    // Event metrics:
+    //  - Intent Submitted API operation
+    //  - Intent Installed operation completion
+    //  - Intent Withdraw Requested API operation
+    //  - Intent Withdrawn operation completion
     //
-    // Timestamps:
-    //  - Intent Submitted API operation (ms from the Epoch)
-    //  - Intent Installed operation completion (ms from the Epoch)
-    //  - Intent Withdraw Requested API operation (ms from the Epoch)
-    //  - Intent Withdrawn operation completion (ms from the Epoch)
-    //
-    private volatile long intentSubmittedTimestampEpochMs = 0;
-    private volatile long intentInstalledTimestampEpochMs = 0;
-    private volatile long intentWithdrawRequestedTimestampEpochMs = 0;
-    private volatile long intentWithdrawnTimestampEpochMs = 0;
-    //
-    private Gauge<Long> intentSubmittedTimestampEpochMsGauge;
-    private Gauge<Long> intentInstalledTimestampEpochMsGauge;
-    private Gauge<Long> intentWithdrawRequestedTimestampEpochMsGauge;
-    private Gauge<Long> intentWithdrawnTimestampEpochMsGauge;
-    //
-    // Rate meters:
-    //  - Rate of the Submitted Intent API operations
-    //  - Rate of the Installed Intent operations
-    //  - Rate of the Withdrawn Requested Intent API operations
-    //  - Rate of the Withdrawn Intent operations
-    //
-    private Meter intentSubmittedRateMeter;
-    private Meter intentInstalledRateMeter;
-    private Meter intentWithdrawRequestedRateMeter;
-    private Meter intentWithdrawnRateMeter;
+    private EventMetric intentSubmittedEventMetric;
+    private EventMetric intentInstalledEventMetric;
+    private EventMetric intentWithdrawRequestedEventMetric;
+    private EventMetric intentWithdrawnEventMetric;
 
     @Activate
     protected void activate() {
@@ -108,43 +81,23 @@
     }
 
     @Override
-    public Gauge<Long> intentSubmittedTimestampEpochMsGauge() {
-        return intentSubmittedTimestampEpochMsGauge;
+    public EventMetric intentSubmittedEventMetric() {
+        return intentSubmittedEventMetric;
     }
 
     @Override
-    public Gauge<Long> intentInstalledTimestampEpochMsGauge() {
-        return intentInstalledTimestampEpochMsGauge;
+    public EventMetric intentInstalledEventMetric() {
+        return intentInstalledEventMetric;
     }
 
     @Override
-    public Gauge<Long> intentWithdrawRequestedTimestampEpochMsGauge() {
-        return intentWithdrawRequestedTimestampEpochMsGauge;
+    public EventMetric intentWithdrawRequestedEventMetric() {
+        return intentWithdrawRequestedEventMetric;
     }
 
     @Override
-    public Gauge<Long> intentWithdrawnTimestampEpochMsGauge() {
-        return intentWithdrawnTimestampEpochMsGauge;
-    }
-
-    @Override
-    public Meter intentSubmittedRateMeter() {
-        return intentSubmittedRateMeter;
-    }
-
-    @Override
-    public Meter intentInstalledRateMeter() {
-        return intentInstalledRateMeter;
-    }
-
-    @Override
-    public Meter intentWithdrawRequestedRateMeter() {
-        return intentWithdrawRequestedRateMeter;
-    }
-
-    @Override
-    public Meter intentWithdrawnRateMeter() {
-        return intentWithdrawnRateMeter;
+    public EventMetric intentWithdrawnEventMetric() {
+        return intentWithdrawnEventMetric;
     }
 
     @Override
@@ -156,26 +109,21 @@
             //
             switch (event.type()) {
             case SUBMITTED:
-                intentSubmittedTimestampEpochMs = System.currentTimeMillis();
-                intentSubmittedRateMeter.mark(1);
+                intentSubmittedEventMetric.eventReceived();
                 break;
             case INSTALLED:
-                intentInstalledTimestampEpochMs = System.currentTimeMillis();
-                intentInstalledRateMeter.mark(1);
+                intentInstalledEventMetric.eventReceived();
                 break;
             case FAILED:
                 // TODO: Just ignore?
                 break;
                 /*
             case WITHDRAW_REQUESTED:
-                intentWithdrawRequestedTimestampEpochMs =
-                    System.currentTimeMillis();
-                    intentWithdrawRequestedRateMeter.mark(1);
+                intentWithdrawRequestedEventMetric.eventReceived();
                 break;
                 */
             case WITHDRAWN:
-                intentWithdrawnTimestampEpochMs = System.currentTimeMillis();
-                intentWithdrawnRateMeter.mark(1);
+                intentWithdrawnEventMetric.eventReceived();
                 break;
             default:
                 break;
@@ -199,10 +147,6 @@
      */
     private void clear() {
         synchronized (lastEvents) {
-            intentSubmittedTimestampEpochMs = 0;
-            intentInstalledTimestampEpochMs = 0;
-            intentWithdrawRequestedTimestampEpochMs = 0;
-            intentWithdrawnTimestampEpochMs = 0;
             lastEvents.clear();
         }
     }
@@ -211,109 +155,32 @@
      * Registers the metrics.
      */
     private void registerMetrics() {
-        metricsComponent = metricsService.registerComponent(COMPONENT_NAME);
-        //
-        metricsFeatureSubmitted =
-            metricsComponent.registerFeature(FEATURE_SUBMITTED_NAME);
-        metricsFeatureInstalled =
-            metricsComponent.registerFeature(FEATURE_INSTALLED_NAME);
-        metricsFeatureWithdrawRequested =
-            metricsComponent.registerFeature(FEATURE_WITHDRAW_REQUESTED_NAME);
-        metricsFeatureWithdrawn =
-            metricsComponent.registerFeature(FEATURE_WITHDRAWN_NAME);
-        //
-        intentSubmittedTimestampEpochMsGauge =
-            metricsService.registerMetric(metricsComponent,
-                                          metricsFeatureSubmitted,
-                                          GAUGE_TIMESTAMP_NAME,
-                                          new Gauge<Long>() {
-                                              @Override
-                                              public Long getValue() {
-                                                  return intentSubmittedTimestampEpochMs;
-                                              }
-                                          });
-        //
-        intentInstalledTimestampEpochMsGauge =
-            metricsService.registerMetric(metricsComponent,
-                                          metricsFeatureInstalled,
-                                          GAUGE_TIMESTAMP_NAME,
-                                          new Gauge<Long>() {
-                                              @Override
-                                              public Long getValue() {
-                                                  return intentInstalledTimestampEpochMs;
-                                              }
-                                          });
-        //
-        intentWithdrawRequestedTimestampEpochMsGauge =
-            metricsService.registerMetric(metricsComponent,
-                                          metricsFeatureWithdrawRequested,
-                                          GAUGE_TIMESTAMP_NAME,
-                                          new Gauge<Long>() {
-                                              @Override
-                                              public Long getValue() {
-                                                  return intentWithdrawRequestedTimestampEpochMs;
-                                              }
-                                          });
-        //
-        intentWithdrawnTimestampEpochMsGauge =
-            metricsService.registerMetric(metricsComponent,
-                                          metricsFeatureWithdrawn,
-                                          GAUGE_TIMESTAMP_NAME,
-                                          new Gauge<Long>() {
-                                              @Override
-                                              public Long getValue() {
-                                                  return intentWithdrawnTimestampEpochMs;
-                                              }
-                                          });
-        //
-        intentSubmittedRateMeter =
-            metricsService.createMeter(metricsComponent,
-                                       metricsFeatureSubmitted,
-                                       METER_RATE_NAME);
-        //
-        intentInstalledRateMeter =
-            metricsService.createMeter(metricsComponent,
-                                       metricsFeatureInstalled,
-                                       METER_RATE_NAME);
-        //
-        intentWithdrawRequestedRateMeter =
-            metricsService.createMeter(metricsComponent,
-                                       metricsFeatureWithdrawRequested,
-                                       METER_RATE_NAME);
-        //
-        intentWithdrawnRateMeter =
-            metricsService.createMeter(metricsComponent,
-                                       metricsFeatureWithdrawn,
-                                       METER_RATE_NAME);
+        intentSubmittedEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_SUBMITTED_NAME);
+        intentInstalledEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_INSTALLED_NAME);
+        intentWithdrawRequestedEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_WITHDRAW_REQUESTED_NAME);
+        intentWithdrawnEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_WITHDRAWN_NAME);
+
+        intentSubmittedEventMetric.registerMetrics();
+        intentInstalledEventMetric.registerMetrics();
+        intentWithdrawRequestedEventMetric.registerMetrics();
+        intentWithdrawnEventMetric.registerMetrics();
     }
 
     /**
      * Removes the metrics.
      */
     private void removeMetrics() {
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureSubmitted,
-                                    GAUGE_TIMESTAMP_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureInstalled,
-                                    GAUGE_TIMESTAMP_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureWithdrawRequested,
-                                    GAUGE_TIMESTAMP_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureWithdrawn,
-                                    GAUGE_TIMESTAMP_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureSubmitted,
-                                    METER_RATE_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureInstalled,
-                                    METER_RATE_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureWithdrawRequested,
-                                    METER_RATE_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureWithdrawn,
-                                    METER_RATE_NAME);
+        intentSubmittedEventMetric.removeMetrics();
+        intentInstalledEventMetric.removeMetrics();
+        intentWithdrawRequestedEventMetric.removeMetrics();
+        intentWithdrawnEventMetric.removeMetrics();
     }
 }
diff --git a/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetricsService.java b/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetricsService.java
index 4acd00f..73df4bc 100644
--- a/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetricsService.java
+++ b/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/IntentMetricsService.java
@@ -1,9 +1,7 @@
 package org.onlab.onos.metrics.intent;
 
 import java.util.List;
-
-import com.codahale.metrics.Gauge;
-import com.codahale.metrics.Meter;
+import org.onlab.metrics.EventMetric;
 import org.onlab.onos.net.intent.IntentEvent;
 
 /**
@@ -18,68 +16,32 @@
     public List<IntentEvent> getEvents();
 
     /**
-     * Gets the Metrics' Gauge for the intent SUBMITTED event timestamp
-     * (ms from the epoch).
+     * Gets the Event Metric for the intent SUBMITTED events.
      *
-     * @return the Metrics' Gauge for the intent SUBMITTED event timestamp
-     * (ms from the epoch)
+     * @return the Event Metric for the intent SUBMITTED events.
      */
-    public Gauge<Long> intentSubmittedTimestampEpochMsGauge();
+    public EventMetric intentSubmittedEventMetric();
 
     /**
-     * Gets the Metrics' Gauge for the intent INSTALLED event timestamp
-     * (ms from the epoch).
+     * Gets the Event Metric for the intent INSTALLED events.
      *
-     * @return the Metrics' Gauge for the intent INSTALLED event timestamp
-     * (ms from the epoch)
+     * @return the Event Metric for the intent INSTALLED events.
      */
-    public Gauge<Long> intentInstalledTimestampEpochMsGauge();
+    public EventMetric intentInstalledEventMetric();
 
     /**
-     * Gets the Metrics' Gauge for the intent WITHDRAW_REQUESTED event
-     * timestamp (ms from the epoch).
+     * Gets the Event Metric for the intent WITHDRAW_REQUESTED events.
      *
      * TODO: This intent event is not implemented yet.
      *
-     * @return the Metrics' Gauge for the intent WITHDRAW_REQUESTED event
-     * timestamp (ms from the epoch)
+     * @return the Event Metric for the intent WITHDRAW_REQUESTED events.
      */
-    public Gauge<Long> intentWithdrawRequestedTimestampEpochMsGauge();
+    public EventMetric intentWithdrawRequestedEventMetric();
 
     /**
-     * Gets the Metrics' Gauge for the intent WITHDRAWN event timestamp
-     * (ms from the epoch).
+     * Gets the Event Metric for the intent WITHDRAWN events.
      *
-     * @return the Metrics' Gauge for the intent WITHDRAWN event timestamp
-     * (ms from the epoch)
+     * @return the Event Metric for the intent WITHDRAWN events.
      */
-    public Gauge<Long> intentWithdrawnTimestampEpochMsGauge();
-
-    /**
-     * Gets the Metrics' Meter for the submitted intents event rate.
-     *
-     * @return the Metrics' Meter for the submitted intents event rate
-     */
-    public Meter intentSubmittedRateMeter();
-
-    /**
-     * Gets the Metrics' Meter for the installed intents event rate.
-     *
-     * @return the Metrics' Meter for the installed intent event rate
-     */
-    public Meter intentInstalledRateMeter();
-
-    /**
-     * Gets the Metrics' Meter for the withdraw requested intents event rate.
-     *
-     * @return the Metrics' Meter for the withdraw requested intents event rate
-     */
-    public Meter intentWithdrawRequestedRateMeter();
-
-    /**
-     * Gets the Metrics' Meter for the withdraw completed intents event rate.
-     *
-     * @return the Metrics' Meter for the withdraw completed intents event rate
-     */
-    public Meter intentWithdrawnRateMeter();
+    public EventMetric intentWithdrawnEventMetric();
 }
diff --git a/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/cli/IntentEventsMetricsCommand.java b/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/cli/IntentEventsMetricsCommand.java
index 204cfd6..6f8d013 100644
--- a/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/cli/IntentEventsMetricsCommand.java
+++ b/apps/metrics/intent/src/main/java/org/onlab/onos/metrics/intent/cli/IntentEventsMetricsCommand.java
@@ -11,6 +11,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import org.apache.karaf.shell.commands.Command;
+import org.onlab.metrics.EventMetric;
 import org.onlab.onos.cli.AbstractShellCommand;
 import org.onlab.onos.metrics.intent.IntentMetricsService;
 
@@ -29,8 +30,6 @@
     @Override
     protected void execute() {
         IntentMetricsService service = get(IntentMetricsService.class);
-        Gauge<Long> gauge;
-        Meter meter;
 
         if (outputJson()) {
             ObjectMapper mapper = new ObjectMapper()
@@ -38,49 +37,49 @@
                                                   TimeUnit.MILLISECONDS,
                                                   false));
             ObjectNode result = mapper.createObjectNode();
-            //
-            gauge = service.intentSubmittedTimestampEpochMsGauge();
-            result.put("intentSubmittedTimestamp", json(mapper, gauge));
-            gauge = service.intentInstalledTimestampEpochMsGauge();
-            result.put("intentInstalledTimestamp", json(mapper, gauge));
-            gauge = service.intentWithdrawRequestedTimestampEpochMsGauge();
-            result.put("intentWithdrawRequestedTimestamp",
-                       json(mapper, gauge));
-            gauge = service.intentWithdrawnTimestampEpochMsGauge();
-            result.put("intentWithdrawnTimestamp", json(mapper, gauge));
-            //
-            meter = service.intentSubmittedRateMeter();
-            result.put("intentSubmittedRate", json(mapper, meter));
-            meter = service.intentInstalledRateMeter();
-            result.put("intentInstalledRate", json(mapper, meter));
-            meter = service.intentWithdrawRequestedRateMeter();
-            result.put("intentWithdrawRequestedRate", json(mapper, meter));
-            meter = service.intentWithdrawnRateMeter();
-            result.put("intentWithdrawnRate", json(mapper, meter));
-            //
+            result = json(mapper, result, "intentSubmitted",
+                          service.intentSubmittedEventMetric());
+            result = json(mapper, result, "intentInstalled",
+                          service.intentInstalledEventMetric());
+            result = json(mapper, result, "intentWithdrawRequested",
+                          service.intentWithdrawRequestedEventMetric());
+            result = json(mapper, result, "intentWithdrawn",
+                          service.intentWithdrawnEventMetric());
             print("%s", result);
         } else {
-            gauge = service.intentSubmittedTimestampEpochMsGauge();
-            printGauge("Submitted", gauge);
-            gauge = service.intentInstalledTimestampEpochMsGauge();
-            printGauge("Installed", gauge);
-            gauge = service.intentWithdrawRequestedTimestampEpochMsGauge();
-            printGauge("Withdraw Requested", gauge);
-            gauge = service.intentWithdrawnTimestampEpochMsGauge();
-            printGauge("Withdrawn", gauge);
-            //
-            meter = service.intentSubmittedRateMeter();
-            printMeter("Submitted", meter);
-            meter = service.intentInstalledRateMeter();
-            printMeter("Installed", meter);
-            meter = service.intentWithdrawRequestedRateMeter();
-            printMeter("Withdraw Requested", meter);
-            meter = service.intentWithdrawnRateMeter();
-            printMeter("Withdrawn", meter);
+            printEventMetric("Submitted",
+                             service.intentSubmittedEventMetric());
+            printEventMetric("Installed",
+                             service.intentInstalledEventMetric());
+            printEventMetric("Withdraw Requested",
+                             service.intentWithdrawRequestedEventMetric());
+            printEventMetric("Withdrawn",
+                             service.intentWithdrawnEventMetric());
         }
     }
 
     /**
+     * Produces JSON node for an Event Metric.
+     *
+     * @param mapper the JSON object mapper to use
+     * @param objectNode the JSON object node to use
+     * @param propertyPrefix the property prefix to use
+     * @param eventMetric the Event Metric with the data
+     * @return JSON object node for the Event Metric
+     */
+    private ObjectNode json(ObjectMapper mapper, ObjectNode objectNode,
+                            String propertyPrefix, EventMetric eventMetric) {
+        String gaugeName = propertyPrefix + "Timestamp";
+        String meterName = propertyPrefix + "Rate";
+        Gauge<Long> gauge = eventMetric.lastEventTimestampGauge();
+        Meter meter = eventMetric.eventRateMeter();
+
+        objectNode.put(gaugeName, json(mapper, gauge));
+        objectNode.put(meterName, json(mapper, meter));
+        return objectNode;
+    }
+
+    /**
      * Produces JSON node for an Object.
      *
      * @param mapper the JSON object mapper to use
@@ -94,8 +93,8 @@
         //
         try {
             final String objectJson = mapper.writeValueAsString(object);
-            JsonNode objectNode = mapper.readTree(objectJson);
-            return objectNode;
+            JsonNode jsonNode = mapper.readTree(objectJson);
+            return jsonNode;
         } catch (JsonProcessingException e) {
             log.error("Error writing value as JSON string", e);
         } catch (IOException e) {
@@ -105,28 +104,26 @@
     }
 
     /**
-     * Prints a Gauge.
+     * Prints an Event Metric.
      *
      * @param operationStr the string with the intent operation to print
-     * @param gauge the Gauge to print
+     * @param eventMetric the Event Metric to print
      */
-    private void printGauge(String operationStr, Gauge<Long> gauge) {
-        print(FORMAT_GAUGE, operationStr, gauge.getValue());
-    }
+    private void printEventMetric(String operationStr,
+                                  EventMetric eventMetric) {
+        Gauge<Long> gauge = eventMetric.lastEventTimestampGauge();
+        Meter meter = eventMetric.eventRateMeter();
+        TimeUnit rateUnit = TimeUnit.SECONDS;
+        double rateFactor = rateUnit.toSeconds(1);
 
-    /**
-     * Prints a Meter.
-     *
-     * @param operationStr the string with the intent operation to print
-     * @param meter the Meter to print
-     */
-    private void printMeter(String operationStr, Meter meter) {
-            TimeUnit rateUnit = TimeUnit.SECONDS;
-            double rateFactor = rateUnit.toSeconds(1);
-            print(FORMAT_METER, operationStr, meter.getCount(),
-                  meter.getMeanRate() * rateFactor,
-                  meter.getOneMinuteRate() * rateFactor,
-                  meter.getFiveMinuteRate() * rateFactor,
-                  meter.getFifteenMinuteRate() * rateFactor);
+        // Print the Gauge
+        print(FORMAT_GAUGE, operationStr, gauge.getValue());
+
+        // Print the Meter
+        print(FORMAT_METER, operationStr, meter.getCount(),
+              meter.getMeanRate() * rateFactor,
+              meter.getOneMinuteRate() * rateFactor,
+              meter.getFiveMinuteRate() * rateFactor,
+              meter.getFifteenMinuteRate() * rateFactor);
     }
 }
diff --git a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetrics.java b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetrics.java
index 32cf0cf..814e178 100644
--- a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetrics.java
+++ b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetrics.java
@@ -5,8 +5,6 @@
 import java.util.LinkedList;
 import java.util.List;
 
-import com.codahale.metrics.Gauge;
-import com.codahale.metrics.Meter;
 import com.google.common.collect.ImmutableList;
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
@@ -14,8 +12,7 @@
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.apache.felix.scr.annotations.Service;
-import org.onlab.metrics.MetricsComponent;
-import org.onlab.metrics.MetricsFeature;
+import org.onlab.metrics.EventMetric;
 import org.onlab.metrics.MetricsService;
 import org.onlab.onos.event.Event;
 import org.onlab.onos.net.device.DeviceEvent;
@@ -48,6 +45,8 @@
     protected LinkService linkService;
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected TopologyService topologyService;
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected MetricsService metricsService;
 
     private LinkedList<Event> lastEvents = new LinkedList<>();
     private static final int LAST_EVENTS_MAX_N = 100;
@@ -61,22 +60,22 @@
     //
     // Metrics
     //
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected MetricsService metricsService;
-    //
     private static final String COMPONENT_NAME = "Topology";
-    private static final String FEATURE_NAME = "EventNotification";
-    private static final String GAUGE_NAME = "LastEventTimestamp.EpochMs";
-    private static final String METER_NAME = "EventRate";
+    private static final String FEATURE_DEVICE_NAME = "DeviceEvent";
+    private static final String FEATURE_HOST_NAME = "HostEvent";
+    private static final String FEATURE_LINK_NAME = "LinkEvent";
+    private static final String FEATURE_GRAPH_NAME = "GraphEvent";
     //
-    private MetricsComponent metricsComponent;
-    private MetricsFeature metricsFeatureEventNotification;
+    // Event metrics:
+    //  - Device events
+    //  - Host events
+    //  - Link events
+    //  - Topology Graph events
     //
-    // Timestamp of the last Topology event (ms from the Epoch)
-    private volatile long lastEventTimestampEpochMs = 0;
-    private Gauge<Long> lastEventTimestampEpochMsGauge;
-    // Rate of the Topology events published to the Topology listeners
-    private Meter eventRateMeter;
+    private EventMetric topologyDeviceEventMetric;
+    private EventMetric topologyHostEventMetric;
+    private EventMetric topologyLinkEventMetric;
+    private EventMetric topologyGraphEventMetric;
 
     @Activate
     protected void activate() {
@@ -113,27 +112,34 @@
     }
 
     @Override
-    public Gauge<Long> lastEventTimestampEpochMsGauge() {
-        return lastEventTimestampEpochMsGauge;
+    public EventMetric topologyDeviceEventMetric() {
+        return topologyDeviceEventMetric;
     }
 
     @Override
-    public Meter eventRateMeter() {
-        return eventRateMeter;
+    public EventMetric topologyHostEventMetric() {
+        return topologyHostEventMetric;
+    }
+
+    @Override
+    public EventMetric topologyLinkEventMetric() {
+        return topologyLinkEventMetric;
+    }
+
+    @Override
+    public EventMetric topologyGraphEventMetric() {
+        return topologyGraphEventMetric;
     }
 
     /**
      * Records an event.
      *
      * @param event the event to record
-     * @param updateEventRateMeter if true, update the Event Rate Meter
+     * @param eventMetric the Event Metric to use
      */
-    private void recordEvent(Event event, boolean updateEventRateMeter) {
+    private void recordEvent(Event event, EventMetric eventMetric) {
         synchronized (lastEvents) {
-            lastEventTimestampEpochMs = System.currentTimeMillis();
-            if (updateEventRateMeter) {
-                eventRateMeter.mark(1);
-            }
+            eventMetric.eventReceived();
 
             //
             // Keep only the last N events, where N = LAST_EVENTS_MAX_N
@@ -151,7 +157,7 @@
     private class InnerDeviceListener implements DeviceListener {
         @Override
         public void event(DeviceEvent event) {
-            recordEvent(event, true);
+            recordEvent(event, topologyDeviceEventMetric);
             log.debug("Device Event: time = {} type = {} event = {}",
                       event.time(), event.type(), event);
         }
@@ -163,7 +169,7 @@
     private class InnerHostListener implements HostListener {
         @Override
         public void event(HostEvent event) {
-            recordEvent(event, true);
+            recordEvent(event, topologyHostEventMetric);
             log.debug("Host Event: time = {} type = {} event = {}",
                       event.time(), event.type(), event);
         }
@@ -175,7 +181,7 @@
     private class InnerLinkListener implements LinkListener {
         @Override
         public void event(LinkEvent event) {
-            recordEvent(event, true);
+            recordEvent(event, topologyLinkEventMetric);
             log.debug("Link Event: time = {} type = {} event = {}",
                       event.time(), event.type(), event);
         }
@@ -187,11 +193,7 @@
     private class InnerTopologyListener implements TopologyListener {
         @Override
         public void event(TopologyEvent event) {
-            //
-            // NOTE: Don't update the eventRateMeter, because the real
-            // events are already captured/counted.
-            //
-            recordEvent(event, false);
+            recordEvent(event, topologyGraphEventMetric);
             log.debug("Topology Event: time = {} type = {} event = {}",
                       event.time(), event.type(), event);
             for (Event reason : event.reasons()) {
@@ -206,7 +208,6 @@
      */
     private void clear() {
         synchronized (lastEvents) {
-            lastEventTimestampEpochMs = 0;
             lastEvents.clear();
         }
     }
@@ -215,35 +216,32 @@
      * Registers the metrics.
      */
     private void registerMetrics() {
-        metricsComponent = metricsService.registerComponent(COMPONENT_NAME);
-        metricsFeatureEventNotification =
-            metricsComponent.registerFeature(FEATURE_NAME);
-        lastEventTimestampEpochMsGauge =
-            metricsService.registerMetric(metricsComponent,
-                                          metricsFeatureEventNotification,
-                                          GAUGE_NAME,
-                                          new Gauge<Long>() {
-                                              @Override
-                                              public Long getValue() {
-                                                  return lastEventTimestampEpochMs;
-                                              }
-                                          });
-        eventRateMeter =
-            metricsService.createMeter(metricsComponent,
-                                       metricsFeatureEventNotification,
-                                       METER_NAME);
+        topologyDeviceEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_DEVICE_NAME);
+        topologyHostEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_HOST_NAME);
+        topologyLinkEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_LINK_NAME);
+        topologyGraphEventMetric =
+            new EventMetric(metricsService, COMPONENT_NAME,
+                            FEATURE_GRAPH_NAME);
 
+        topologyDeviceEventMetric.registerMetrics();
+        topologyHostEventMetric.registerMetrics();
+        topologyLinkEventMetric.registerMetrics();
+        topologyGraphEventMetric.registerMetrics();
     }
 
     /**
      * Removes the metrics.
      */
     private void removeMetrics() {
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureEventNotification,
-                                    GAUGE_NAME);
-        metricsService.removeMetric(metricsComponent,
-                                    metricsFeatureEventNotification,
-                                    METER_NAME);
+        topologyDeviceEventMetric.removeMetrics();
+        topologyHostEventMetric.removeMetrics();
+        topologyLinkEventMetric.removeMetrics();
+        topologyGraphEventMetric.removeMetrics();
     }
 }
diff --git a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
index aeb2e32..9203d9b 100644
--- a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
+++ b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
@@ -1,9 +1,7 @@
 package org.onlab.onos.metrics.topology;
 
 import java.util.List;
-
-import com.codahale.metrics.Gauge;
-import com.codahale.metrics.Meter;
+import org.onlab.metrics.EventMetric;
 import org.onlab.onos.event.Event;
 
 /**
@@ -18,18 +16,30 @@
     public List<Event> getEvents();
 
     /**
-     * Gets the Metrics' Gauge for the last topology event timestamp
-     * (ms from the epoch).
+     * Gets the Event Metric for the Device Events.
      *
-     * @return the Metrics' Gauge for the last topology event timestamp
-     * (ms from the epoch)
+     * @return the Event Metric for the Device Events.
      */
-    public Gauge<Long> lastEventTimestampEpochMsGauge();
+    public EventMetric topologyDeviceEventMetric();
 
     /**
-     * Gets the Metrics' Meter for the topology events rate.
+     * Gets the Event Metric for the Host Events.
      *
-     * @return the Metrics' Meter for the topology events rate
+     * @return the Event Metric for the Host Events.
      */
-    public Meter eventRateMeter();
+    public EventMetric topologyHostEventMetric();
+
+    /**
+     * Gets the Event Metric for the Link Events.
+     *
+     * @return the Event Metric for the Link Events.
+     */
+    public EventMetric topologyLinkEventMetric();
+
+    /**
+     * Gets the Event Metric for the Topology Graph Events.
+     *
+     * @return the Event Metric for the Topology Graph Events.
+     */
+    public EventMetric topologyGraphEventMetric();
 }
diff --git a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/cli/TopologyEventsMetricsCommand.java b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/cli/TopologyEventsMetricsCommand.java
index 54d3a95..b7e0401 100644
--- a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/cli/TopologyEventsMetricsCommand.java
+++ b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/cli/TopologyEventsMetricsCommand.java
@@ -11,6 +11,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import org.apache.karaf.shell.commands.Command;
+import org.onlab.metrics.EventMetric;
 import org.onlab.onos.cli.AbstractShellCommand;
 import org.onlab.onos.metrics.topology.TopologyMetricsService;
 
@@ -22,15 +23,13 @@
 public class TopologyEventsMetricsCommand extends AbstractShellCommand {
 
     private static final String FORMAT_GAUGE =
-        "Last Topology Event Timestamp (ms from epoch)=%d";
+        "Topology %s Event Timestamp (ms from epoch)=%d";
     private static final String FORMAT_METER =
-        "Topology Events count=%d rate(events/sec) mean=%f m1=%f m5=%f m15=%f";
+        "Topology %s Events count=%d rate(events/sec) mean=%f m1=%f m5=%f m15=%f";
 
     @Override
     protected void execute() {
         TopologyMetricsService service = get(TopologyMetricsService.class);
-        Gauge<Long> gauge = service.lastEventTimestampEpochMsGauge();
-        Meter meter = service.eventRateMeter();
 
         if (outputJson()) {
             ObjectMapper mapper = new ObjectMapper()
@@ -38,32 +37,89 @@
                                                   TimeUnit.MILLISECONDS,
                                                   false));
             ObjectNode result = mapper.createObjectNode();
-            try {
-                //
-                // NOTE: The API for custom serializers is incomplete,
-                // hence we have to parse the JSON string to create JsonNode.
-                //
-                final String gaugeJson = mapper.writeValueAsString(gauge);
-                final String meterJson = mapper.writeValueAsString(meter);
-                JsonNode gaugeNode = mapper.readTree(gaugeJson);
-                JsonNode meterNode = mapper.readTree(meterJson);
-                result.put("lastTopologyEventTimestamp", gaugeNode);
-                result.put("topologyEventRate", meterNode);
-            } catch (JsonProcessingException e) {
-                log.error("Error writing value as JSON string", e);
-            } catch (IOException e) {
-                log.error("Error writing value as JSON string", e);
-            }
+            result = json(mapper, result, "topologyDeviceEvent",
+                          service.topologyDeviceEventMetric());
+            result = json(mapper, result, "topologyHostEvent",
+                          service.topologyHostEventMetric());
+            result = json(mapper, result, "topologyLinkEvent",
+                          service.topologyLinkEventMetric());
+            result = json(mapper, result, "topologyGraphEvent",
+                          service.topologyGraphEventMetric());
             print("%s", result);
         } else {
-            TimeUnit rateUnit = TimeUnit.SECONDS;
-            double rateFactor = rateUnit.toSeconds(1);
-            print(FORMAT_GAUGE, gauge.getValue());
-            print(FORMAT_METER, meter.getCount(),
-                  meter.getMeanRate() * rateFactor,
-                  meter.getOneMinuteRate() * rateFactor,
-                  meter.getFiveMinuteRate() * rateFactor,
-                  meter.getFifteenMinuteRate() * rateFactor);
+            printEventMetric("Device", service.topologyDeviceEventMetric());
+            printEventMetric("Host", service.topologyHostEventMetric());
+            printEventMetric("Link", service.topologyLinkEventMetric());
+            printEventMetric("Graph", service.topologyGraphEventMetric());
         }
     }
+
+    /**
+     * Produces JSON node for an Event Metric.
+     *
+     * @param mapper the JSON object mapper to use
+     * @param objectNode the JSON object node to use
+     * @param propertyPrefix the property prefix to use
+     * @param eventMetric the Event Metric with the data
+     * @return JSON object node for the Event Metric
+     */
+    private ObjectNode json(ObjectMapper mapper, ObjectNode objectNode,
+                            String propertyPrefix, EventMetric eventMetric) {
+        String gaugeName = propertyPrefix + "Timestamp";
+        String meterName = propertyPrefix + "Rate";
+        Gauge<Long> gauge = eventMetric.lastEventTimestampGauge();
+        Meter meter = eventMetric.eventRateMeter();
+
+        objectNode.put(gaugeName, json(mapper, gauge));
+        objectNode.put(meterName, json(mapper, meter));
+        return objectNode;
+    }
+
+    /**
+     * Produces JSON node for an Object.
+     *
+     * @param mapper the JSON object mapper to use
+     * @param object the Object with the data
+     * @return JSON node for the Object
+     */
+    private JsonNode json(ObjectMapper mapper, Object object) {
+        //
+        // NOTE: The API for custom serializers is incomplete,
+        // hence we have to parse the JSON string to create JsonNode.
+        //
+        try {
+            final String objectJson = mapper.writeValueAsString(object);
+            JsonNode jsonNode = mapper.readTree(objectJson);
+            return jsonNode;
+        } catch (JsonProcessingException e) {
+            log.error("Error writing value as JSON string", e);
+        } catch (IOException e) {
+            log.error("Error writing value as JSON string", e);
+        }
+        return null;
+    }
+
+    /**
+     * Prints an Event Metric.
+     *
+     * @param operationStr the string with the intent operation to print
+     * @param eventMetric the Event Metric to print
+     */
+    private void printEventMetric(String operationStr,
+                                  EventMetric eventMetric) {
+        Gauge<Long> gauge = eventMetric.lastEventTimestampGauge();
+        Meter meter = eventMetric.eventRateMeter();
+        TimeUnit rateUnit = TimeUnit.SECONDS;
+        double rateFactor = rateUnit.toSeconds(1);
+
+        // Print the Gauge
+        print(FORMAT_GAUGE, operationStr, gauge.getValue());
+
+        // Print the Meter
+        print(FORMAT_METER, operationStr, meter.getCount(),
+              meter.getMeanRate() * rateFactor,
+              meter.getOneMinuteRate() * rateFactor,
+              meter.getFiveMinuteRate() * rateFactor,
+              meter.getFifteenMinuteRate() * rateFactor);
+    }
 }
diff --git a/core/api/src/main/java/org/onlab/onos/codec/CodecService.java b/core/api/src/main/java/org/onlab/onos/codec/CodecService.java
new file mode 100644
index 0000000..c6dbda2
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/codec/CodecService.java
@@ -0,0 +1,58 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.onlab.onos.codec;
+
+import java.util.Set;
+
+/**
+ * Service for registering and retrieving JSON codecs for various entities.
+ */
+public interface CodecService {
+
+    /**
+     * Returns the set of classes with currently registered codecs.
+     *
+     * @return set of entity classes
+     */
+    Set<Class<?>> getCodecs();
+
+    /**
+     * Returns the JSON codec for the specified entity class.
+     *
+     * @param entityClass entity class
+     * @return JSON codec; null if no codec available for the class
+     */
+    JsonCodec getCodec(Class<?> entityClass);
+
+    /**
+     * Registers the specified JSON codec for the given entity class.
+     *
+     * @param entityClass entity class
+     * @param codec       JSON codec
+     */
+    void registerCodec(Class<?> entityClass, JsonCodec codec);
+
+    /**
+     * Unregisters the JSON codec for the specified entity class.
+     *
+     * @param entityClass entity class
+     */
+    void unregisterCodec(Class<?> entityClass);
+
+}
diff --git a/core/api/src/main/java/org/onlab/onos/codec/JsonCodec.java b/core/api/src/main/java/org/onlab/onos/codec/JsonCodec.java
new file mode 100644
index 0000000..4338cde
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/codec/JsonCodec.java
@@ -0,0 +1,88 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.onlab.onos.codec;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Abstraction of a codec capable for encoding/decoding arbitrary objects to/from JSON.
+ */
+public abstract class JsonCodec<T> {
+
+    /**
+     * Encodes the specified entity into JSON.
+     *
+     * @param entity entity to encode
+     * @param mapper object mapper
+     * @return JSON node
+     * @throws java.lang.UnsupportedOperationException if the codec does not
+     *                                                 support encode operations
+     */
+    public abstract ObjectNode encode(T entity, ObjectMapper mapper);
+
+    /**
+     * Decodes the specified entity from JSON.
+     *
+     * @param json JSON to decode
+     * @return decoded entity
+     * @throws java.lang.UnsupportedOperationException if the codec does not
+     *                                                 support decode operations
+     */
+    public abstract T decode(ObjectNode json);
+
+    /**
+     * Encodes the collection of the specified entities.
+     *
+     * @param entities collection of entities to encode
+     * @param mapper   object mapper
+     * @return JSON array
+     * @throws java.lang.UnsupportedOperationException if the codec does not
+     *                                                 support encode operations
+     */
+    public ArrayNode encode(Iterable<T> entities, ObjectMapper mapper) {
+        ArrayNode result = mapper.createArrayNode();
+        for (T entity : entities) {
+            result.add(encode(entity, mapper));
+        }
+        return result;
+    }
+
+    /**
+     * Decodes the specified JSON array into a collection of entities.
+     *
+     * @param json JSON array to decode
+     * @return collection of decoded entities
+     * @throws java.lang.UnsupportedOperationException if the codec does not
+     *                                                 support decode operations
+     */
+    public List<T> decode(ArrayNode json) {
+        List<T> result = new ArrayList<>();
+        for (JsonNode node : json) {
+            result.add(decode((ObjectNode) node));
+        }
+        return result;
+    }
+
+}
diff --git a/core/api/src/main/java/org/onlab/onos/codec/package-info.java b/core/api/src/main/java/org/onlab/onos/codec/package-info.java
new file mode 100644
index 0000000..33d6d8c
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/codec/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+/**
+ * Base JSON codec abstraction and a service for tracking various JSON codecs.
+ */
+package org.onlab.onos.codec;
\ No newline at end of file
diff --git a/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchEvent.java b/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchEvent.java
index 4ba3366..d0d1820 100644
--- a/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchEvent.java
@@ -30,7 +30,7 @@
      * @param request batch operation request.
      * @return event.
      */
-    public static FlowRuleBatchEvent create(FlowRuleBatchRequest request) {
+    public static FlowRuleBatchEvent requested(FlowRuleBatchRequest request) {
         FlowRuleBatchEvent event = new FlowRuleBatchEvent(Type.BATCH_OPERATION_REQUESTED, request, null);
         return event;
     }
@@ -41,7 +41,7 @@
      * @param result completed batch operation result.
      * @return event.
      */
-    public static FlowRuleBatchEvent create(FlowRuleBatchRequest request, CompletedBatchOperation result) {
+    public static FlowRuleBatchEvent completed(FlowRuleBatchRequest request, CompletedBatchOperation result) {
         FlowRuleBatchEvent event = new FlowRuleBatchEvent(Type.BATCH_OPERATION_COMPLETED, request, result);
         return event;
     }
diff --git a/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchRequest.java b/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchRequest.java
index 0414fcb..34e3d31 100644
--- a/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchRequest.java
+++ b/core/api/src/main/java/org/onlab/onos/net/flow/FlowRuleBatchRequest.java
@@ -9,10 +9,12 @@
 
 public class FlowRuleBatchRequest {
 
+    private final int batchId;
     private final List<FlowEntry> toAdd;
     private final List<FlowEntry> toRemove;
 
-    public FlowRuleBatchRequest(List<FlowEntry> toAdd, List<FlowEntry> toRemove) {
+    public FlowRuleBatchRequest(int batchId, List<FlowEntry> toAdd, List<FlowEntry> toRemove) {
+        this.batchId = batchId;
         this.toAdd = Collections.unmodifiableList(toAdd);
         this.toRemove = Collections.unmodifiableList(toRemove);
     }
@@ -35,4 +37,8 @@
         }
         return new FlowRuleBatchOperation(entries);
     }
+
+    public int batchId() {
+        return batchId;
+    }
 }
diff --git a/core/api/src/test/java/org/onlab/onos/codec/JsonCodecTest.java b/core/api/src/test/java/org/onlab/onos/codec/JsonCodecTest.java
new file mode 100644
index 0000000..f3a10e3
--- /dev/null
+++ b/core/api/src/test/java/org/onlab/onos/codec/JsonCodecTest.java
@@ -0,0 +1,85 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.onlab.onos.codec;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.google.common.collect.ImmutableList;
+import org.junit.Test;
+
+import java.util.List;
+import java.util.Objects;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Test of the base JSON codec abstraction.
+ */
+public class JsonCodecTest {
+
+    private static class Foo {
+        final String name;
+
+        Foo(String name) {
+            this.name = name;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(name);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj == null || getClass() != obj.getClass()) {
+                return false;
+            }
+            final Foo other = (Foo) obj;
+            return Objects.equals(this.name, other.name);
+        }
+    }
+
+    private static class FooCodec extends JsonCodec<Foo> {
+        @Override
+        public ObjectNode encode(Foo entity, ObjectMapper mapper) {
+            return mapper.createObjectNode().put("name", entity.name);
+        }
+
+        @Override
+        public Foo decode(ObjectNode json) {
+            return new Foo(json.get("name").asText());
+        }
+    }
+
+    @Test
+    public void encode() {
+        Foo f1 = new Foo("foo");
+        Foo f2 = new Foo("bar");
+        FooCodec codec = new FooCodec();
+        ImmutableList<Foo> entities = ImmutableList.of(f1, f2);
+        ArrayNode json = codec.encode(entities, new ObjectMapper());
+        List<Foo> foos = codec.decode(json);
+        assertEquals("incorrect encode/decode", entities, foos);
+    }
+
+}
\ No newline at end of file
diff --git a/core/net/src/main/java/org/onlab/onos/net/flow/impl/FlowRuleManager.java b/core/net/src/main/java/org/onlab/onos/net/flow/impl/FlowRuleManager.java
index 3ef9fc8..60ab307 100644
--- a/core/net/src/main/java/org/onlab/onos/net/flow/impl/FlowRuleManager.java
+++ b/core/net/src/main/java/org/onlab/onos/net/flow/impl/FlowRuleManager.java
@@ -2,12 +2,14 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static org.slf4j.LoggerFactory.getLogger;
+import static org.onlab.util.Tools.namedThreads;
 
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
@@ -74,6 +76,9 @@
 
     private final FlowRuleStoreDelegate delegate = new InternalStoreDelegate();
 
+    private final ExecutorService futureListeners =
+            Executors.newCachedThreadPool(namedThreads("provider-future-listeners"));
+
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected FlowRuleStore store;
 
@@ -92,6 +97,8 @@
 
     @Deactivate
     public void deactivate() {
+        futureListeners.shutdownNow();
+
         store.unsetDelegate(delegate);
         eventDispatcher.removeSink(FlowRuleEvent.class);
         log.info("Stopped");
@@ -398,9 +405,10 @@
                 result.addListener(new Runnable() {
                     @Override
                     public void run() {
-                        store.batchOperationComplete(FlowRuleBatchEvent.create(request, Futures.getUnchecked(result)));
+                        store.batchOperationComplete(FlowRuleBatchEvent.completed(request,
+                                                                                  Futures.getUnchecked(result)));
                     }
-                }, Executors.newCachedThreadPool());
+                }, futureListeners);
 
                 break;
             case BATCH_OPERATION_COMPLETED:
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/cluster/messaging/impl/ClusterCommunicationManager.java b/core/store/dist/src/main/java/org/onlab/onos/store/cluster/messaging/impl/ClusterCommunicationManager.java
index 4db23ce..b2f679c 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/cluster/messaging/impl/ClusterCommunicationManager.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/cluster/messaging/impl/ClusterCommunicationManager.java
@@ -103,7 +103,7 @@
         final ControllerNode localNode = clusterService.getLocalNode();
         for (NodeId nodeId : nodes) {
             if (!nodeId.equals(localNode.id())) {
-                ok = unicast(message, nodeId) && ok;
+                ok = unicastUnchecked(message, nodeId) && ok;
             }
         }
         return ok;
@@ -124,6 +124,14 @@
         }
     }
 
+    private boolean unicastUnchecked(ClusterMessage message, NodeId toNodeId) throws IOException {
+        try {
+            return unicast(message, toNodeId);
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
     @Override
     public ClusterMessageResponse sendAndReceive(ClusterMessage message, NodeId toNodeId) throws IOException {
         ControllerNode node = clusterService.getNode(toNodeId);
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/DistributedFlowRuleStore.java b/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/DistributedFlowRuleStore.java
index 85f928a..e5aa3e8 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/DistributedFlowRuleStore.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/DistributedFlowRuleStore.java
@@ -3,15 +3,20 @@
 import static org.onlab.onos.net.flow.FlowRuleEvent.Type.RULE_REMOVED;
 import static org.slf4j.LoggerFactory.getLogger;
 import static org.onlab.onos.store.flow.impl.FlowStoreMessageSubjects.*;
+import static org.onlab.util.Tools.namedThreads;
 
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Map;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.List;
 
 import org.apache.felix.scr.annotations.Activate;
@@ -22,7 +27,9 @@
 import org.apache.felix.scr.annotations.Service;
 import org.onlab.onos.ApplicationId;
 import org.onlab.onos.cluster.ClusterService;
+import org.onlab.onos.net.Device;
 import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.device.DeviceService;
 import org.onlab.onos.net.flow.CompletedBatchOperation;
 import org.onlab.onos.net.flow.DefaultFlowEntry;
 import org.onlab.onos.net.flow.FlowEntry;
@@ -52,8 +59,12 @@
 
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.SettableFuture;
 
 /**
  * Manages inventory of flow rules using a distributed state management protocol.
@@ -74,13 +85,26 @@
             ArrayListMultimap.<Short, FlowRule>create();
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    private ReplicaInfoService replicaInfoManager;
+    protected ReplicaInfoService replicaInfoManager;
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    private ClusterCommunicationService clusterCommunicator;
+    protected ClusterCommunicationService clusterCommunicator;
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    private ClusterService clusterService;
+    protected ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+
+    private final AtomicInteger localBatchIdGen = new AtomicInteger();
+
+
+    // FIXME switch to expiraing map/Cache?
+    private Map<Integer, SettableFuture<CompletedBatchOperation>> pendingFutures = Maps.newConcurrentMap();
+
+    private final ExecutorService futureListeners =
+            Executors.newCachedThreadPool(namedThreads("flowstore-peer-responders"));
+
 
     protected static final KryoSerializer SERIALIZER = new KryoSerializer() {
         @Override
@@ -97,36 +121,26 @@
 
     @Activate
     public void activate() {
-        clusterCommunicator.addSubscriber(STORE_FLOW_RULE, new ClusterMessageHandler() {
+        clusterCommunicator.addSubscriber(APPLY_BATCH_FLOWS, new ClusterMessageHandler() {
 
             @Override
-            public void handle(ClusterMessage message) {
-                FlowRule rule = SERIALIZER.decode(message.payload());
-                log.info("received add request for {}", rule);
-                storeFlowRule(rule);
-                // FIXME what to respond.
-                try {
-                    message.respond(SERIALIZER.encode("ACK"));
-                } catch (IOException e) {
-                    log.error("Failed to respond back", e);
-                }
-            }
-        });
+            public void handle(final ClusterMessage message) {
+                FlowRuleBatchOperation operation = SERIALIZER.decode(message.payload());
+                log.info("received batch request {}", operation);
+                final ListenableFuture<CompletedBatchOperation> f = storeBatchInternal(operation);
 
-        clusterCommunicator.addSubscriber(DELETE_FLOW_RULE, new ClusterMessageHandler() {
+                f.addListener(new Runnable() {
 
-            @Override
-            public void handle(ClusterMessage message) {
-                FlowRule rule = SERIALIZER.decode(message.payload());
-                log.info("received delete request for {}", rule);
-                deleteFlowRule(rule);
-                // FIXME what to respond.
-                try {
-                    message.respond(SERIALIZER.encode("ACK"));
-                } catch (IOException e) {
-                    log.error("Failed to respond back", e);
-                }
-
+                    @Override
+                    public void run() {
+                         CompletedBatchOperation result = Futures.getUnchecked(f);
+                        try {
+                            message.respond(SERIALIZER.encode(result));
+                        } catch (IOException e) {
+                            log.error("Failed to respond back", e);
+                        }
+                    }
+                }, futureListeners);
             }
         });
 
@@ -159,7 +173,13 @@
     // make it device specific.
     @Override
     public int getFlowRuleCount() {
-        return flowEntries.size();
+        // implementing in-efficient operation for debugging purpose.
+        int sum = 0;
+        for (Device device : deviceService.getDevices()) {
+            final DeviceId did = device.id();
+            sum += Iterables.size(getFlowEntries(did));
+        }
+        return sum;
     }
 
     @Override
@@ -218,6 +238,7 @@
         storeBatch(new FlowRuleBatchOperation(Arrays.asList(new FlowRuleBatchEntry(FlowRuleOperation.ADD, rule))));
     }
 
+    @Override
     public Future<CompletedBatchOperation> storeBatch(FlowRuleBatchOperation operation) {
         if (operation.getOperations().isEmpty()) {
             return Futures.immediateFuture(new CompletedBatchOperation(true, Collections.<FlowEntry>emptySet()));
@@ -236,7 +257,7 @@
 
         ClusterMessage message = new ClusterMessage(
                 clusterService.getLocalNode().id(),
-                FlowStoreMessageSubjects.STORE_FLOW_RULE,
+                APPLY_BATCH_FLOWS,
                 SERIALIZER.encode(operation));
 
         try {
@@ -250,7 +271,7 @@
         return null;
     }
 
-    private Future<CompletedBatchOperation> storeBatchInternal(FlowRuleBatchOperation operation) {
+    private ListenableFuture<CompletedBatchOperation> storeBatchInternal(FlowRuleBatchOperation operation) {
         List<FlowEntry> toRemove = new ArrayList<>();
         List<FlowEntry> toAdd = new ArrayList<>();
         // TODO: backup changes to hazelcast map
@@ -261,8 +282,8 @@
                 StoredFlowEntry entry = getFlowEntryInternal(flowRule);
                 if (entry != null) {
                     entry.setState(FlowEntryState.PENDING_REMOVE);
+                    toRemove.add(entry);
                 }
-                toRemove.add(entry);
             } else if (op.equals(FlowRuleOperation.ADD)) {
                 StoredFlowEntry flowEntry = new DefaultFlowEntry(flowRule);
                 DeviceId deviceId = flowRule.deviceId();
@@ -276,9 +297,13 @@
         if (toAdd.isEmpty() && toRemove.isEmpty()) {
             return Futures.immediateFuture(new CompletedBatchOperation(true, Collections.<FlowEntry>emptySet()));
         }
-        notifyDelegate(FlowRuleBatchEvent.create(new FlowRuleBatchRequest(toAdd, toRemove)));
-        // TODO: imlpement this.
-        return Futures.immediateFailedFuture(new RuntimeException("Implement this."));
+
+        SettableFuture<CompletedBatchOperation> r = SettableFuture.create();
+        final int batchId = localBatchIdGen.incrementAndGet();
+
+        pendingFutures.put(batchId, r);
+        notifyDelegate(FlowRuleBatchEvent.requested(new FlowRuleBatchRequest(batchId, toAdd, toRemove)));
+        return r;
     }
 
     @Override
@@ -293,18 +318,9 @@
             return addOrUpdateFlowRuleInternal(rule);
         }
 
-        ClusterMessage message = new ClusterMessage(
-                clusterService.getLocalNode().id(),
-                FlowStoreMessageSubjects.ADD_OR_UPDATE_FLOW_RULE,
-                SERIALIZER.encode(rule));
-
-        try {
-            ClusterMessageResponse response = clusterCommunicator.sendAndReceive(message, replicaInfo.master().get());
-            return SERIALIZER.decode(response.get(FLOW_RULE_STORE_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS));
-        } catch (IOException | TimeoutException e) {
-            // FIXME: throw a FlowStoreException
-            throw new RuntimeException(e);
-        }
+        log.error("Tried to update FlowRule {} state,"
+                + " while the Node was not the master.", rule);
+        return null;
     }
 
     private synchronized FlowRuleEvent addOrUpdateFlowRuleInternal(FlowEntry rule) {
@@ -338,18 +354,9 @@
             return removeFlowRuleInternal(rule);
         }
 
-        ClusterMessage message = new ClusterMessage(
-                clusterService.getLocalNode().id(),
-                FlowStoreMessageSubjects.REMOVE_FLOW_RULE,
-                SERIALIZER.encode(rule));
-
-        try {
-            ClusterMessageResponse response = clusterCommunicator.sendAndReceive(message, replicaInfo.master().get());
-            return SERIALIZER.decode(response.get(FLOW_RULE_STORE_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS));
-        } catch (IOException | TimeoutException e) {
-            // FIXME: throw a FlowStoreException
-            throw new RuntimeException(e);
-        }
+        log.error("Tried to remove FlowRule {},"
+                + " while the Node was not the master.", rule);
+        return null;
     }
 
     private synchronized FlowRuleEvent removeFlowRuleInternal(FlowEntry rule) {
@@ -364,6 +371,11 @@
 
     @Override
     public void batchOperationComplete(FlowRuleBatchEvent event) {
+        SettableFuture<CompletedBatchOperation> future
+            = pendingFutures.get(event.subject().batchId());
+        if (future != null) {
+            future.set(event.result());
+        }
         notifyDelegate(event);
     }
 }
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/FlowStoreMessageSubjects.java b/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/FlowStoreMessageSubjects.java
index ca833b8..ef68b55 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/FlowStoreMessageSubjects.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/flow/impl/FlowStoreMessageSubjects.java
@@ -7,10 +7,10 @@
  */
 public final class FlowStoreMessageSubjects {
     private FlowStoreMessageSubjects() {}
-    public static final  MessageSubject STORE_FLOW_RULE = new MessageSubject("peer-forward-store-flow-rule");
-    public static final MessageSubject DELETE_FLOW_RULE = new MessageSubject("peer-forward-delete-flow-rule");
-    public static final MessageSubject ADD_OR_UPDATE_FLOW_RULE =
-        new MessageSubject("peer-forward-add-or-update-flow-rule");
-    public static final MessageSubject REMOVE_FLOW_RULE = new MessageSubject("peer-forward-remove-flow-rule");
-    public static final MessageSubject GET_FLOW_ENTRY = new MessageSubject("peer-forward-get-flow-entry");
+
+    public static final  MessageSubject APPLY_BATCH_FLOWS
+        = new MessageSubject("peer-forward-apply-batch");
+
+    public static final MessageSubject GET_FLOW_ENTRY
+        = new MessageSubject("peer-forward-get-flow-entry");
 }
diff --git a/core/store/hz/cluster/src/main/java/org/onlab/onos/store/mastership/impl/DistributedMastershipStore.java b/core/store/hz/cluster/src/main/java/org/onlab/onos/store/mastership/impl/DistributedMastershipStore.java
index 316a3b4..f9352fe 100644
--- a/core/store/hz/cluster/src/main/java/org/onlab/onos/store/mastership/impl/DistributedMastershipStore.java
+++ b/core/store/hz/cluster/src/main/java/org/onlab/onos/store/mastership/impl/DistributedMastershipStore.java
@@ -58,7 +58,6 @@
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected ClusterService clusterService;
 
-    @SuppressWarnings({ "unchecked", "rawtypes" })
     @Override
     @Activate
     public void activate() {
@@ -76,9 +75,9 @@
             }
         };
 
-        roleMap = new SMap(theInstance.getMap("nodeRoles"), this.serializer);
+        roleMap = new SMap<>(theInstance.<byte[], byte[]>getMap("nodeRoles"), this.serializer);
         roleMap.addEntryListener((new RemoteMasterShipEventHandler()), true);
-        terms = new SMap(theInstance.getMap("terms"), this.serializer);
+        terms = new SMap<>(theInstance.<byte[], byte[]>getMap("terms"), this.serializer);
         clusterSize = theInstance.getAtomicLong("clustersize");
 
         log.info("Started");
diff --git a/core/store/serializers/src/main/java/org/onlab/onos/store/serializers/KryoNamespaces.java b/core/store/serializers/src/main/java/org/onlab/onos/store/serializers/KryoNamespaces.java
index 7fddb01..0e9e19c 100644
--- a/core/store/serializers/src/main/java/org/onlab/onos/store/serializers/KryoNamespaces.java
+++ b/core/store/serializers/src/main/java/org/onlab/onos/store/serializers/KryoNamespaces.java
@@ -5,6 +5,7 @@
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedList;
 
 import org.onlab.onos.cluster.ControllerNode;
 import org.onlab.onos.cluster.DefaultControllerNode;
@@ -27,12 +28,15 @@
 import org.onlab.onos.net.PortNumber;
 import org.onlab.onos.net.device.DefaultDeviceDescription;
 import org.onlab.onos.net.device.DefaultPortDescription;
+import org.onlab.onos.net.flow.CompletedBatchOperation;
 import org.onlab.onos.net.flow.DefaultFlowEntry;
 import org.onlab.onos.net.flow.DefaultFlowRule;
 import org.onlab.onos.net.flow.DefaultTrafficSelector;
 import org.onlab.onos.net.flow.DefaultTrafficTreatment;
 import org.onlab.onos.net.flow.FlowEntry;
 import org.onlab.onos.net.flow.FlowId;
+import org.onlab.onos.net.flow.FlowRuleBatchEntry;
+import org.onlab.onos.net.flow.FlowRuleBatchOperation;
 import org.onlab.onos.net.flow.StoredFlowEntry;
 import org.onlab.onos.net.flow.criteria.Criteria;
 import org.onlab.onos.net.flow.criteria.Criterion;
@@ -80,6 +84,7 @@
                     Arrays.asList().getClass(),
                     HashMap.class,
                     HashSet.class,
+                    LinkedList.class,
                     //
                     //
                     ControllerNode.State.class,
@@ -118,7 +123,11 @@
                     DefaultTrafficTreatment.class,
                     Instructions.DropInstruction.class,
                     Instructions.OutputInstruction.class,
-                    RoleInfo.class
+                    RoleInfo.class,
+                    FlowRuleBatchOperation.class,
+                    CompletedBatchOperation.class,
+                    FlowRuleBatchEntry.class,
+                    FlowRuleBatchEntry.FlowRuleOperation.class
                     )
             .register(URI.class, new URISerializer())
             .register(NodeId.class, new NodeIdSerializer())
diff --git a/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleFlowRuleStore.java b/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleFlowRuleStore.java
index bbfc263..82ea4e2 100644
--- a/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleFlowRuleStore.java
+++ b/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleFlowRuleStore.java
@@ -1,19 +1,8 @@
 package org.onlab.onos.store.trivial.impl;
 
-import static org.onlab.onos.net.flow.FlowRuleEvent.Type.RULE_REMOVED;
-import static org.slf4j.LoggerFactory.getLogger;
-import static org.apache.commons.lang3.concurrent.ConcurrentUtils.createIfAbsentUnchecked;
-
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
-import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.concurrent.Future;
-
+import com.google.common.base.Function;
+import com.google.common.collect.FluentIterable;
+import com.google.common.util.concurrent.Futures;
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
@@ -40,9 +29,19 @@
 import org.onlab.util.NewConcurrentHashMap;
 import org.slf4j.Logger;
 
-import com.google.common.base.Function;
-import com.google.common.collect.FluentIterable;
-import com.google.common.util.concurrent.Futures;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.Future;
+
+import static org.apache.commons.lang3.concurrent.ConcurrentUtils.createIfAbsentUnchecked;
+import static org.onlab.onos.net.flow.FlowRuleEvent.Type.RULE_REMOVED;
+import static org.slf4j.LoggerFactory.getLogger;
 
 /**
  * Manages inventory of flow rules using trivial in-memory implementation.
@@ -132,15 +131,15 @@
     public Iterable<FlowEntry> getFlowEntries(DeviceId deviceId) {
         // flatten and make iterator unmodifiable
         return FluentIterable.from(getFlowTable(deviceId).values())
-            .transformAndConcat(
-                    new Function<List<StoredFlowEntry>, Iterable<? extends FlowEntry>>() {
+                .transformAndConcat(
+                        new Function<List<StoredFlowEntry>, Iterable<? extends FlowEntry>>() {
 
-                @Override
-                public Iterable<? extends FlowEntry> apply(
-                        List<StoredFlowEntry> input) {
-                    return Collections.unmodifiableList(input);
-                }
-            });
+                            @Override
+                            public Iterable<? extends FlowEntry> apply(
+                                    List<StoredFlowEntry> input) {
+                                return Collections.unmodifiableList(input);
+                            }
+                        });
     }
 
     @Override
@@ -176,10 +175,10 @@
             }
             // new flow rule added
             existing.add(f);
-            notifyDelegate(FlowRuleBatchEvent.create(
-                    new FlowRuleBatchRequest(
-                            Arrays.<FlowEntry>asList(f),
-                            Collections.<FlowEntry>emptyList())));
+            notifyDelegate(FlowRuleBatchEvent.requested(
+                    new FlowRuleBatchRequest(1, /* FIXME generate something */
+                                             Arrays.<FlowEntry>asList(f),
+                                             Collections.<FlowEntry>emptyList())));
         }
     }
 
@@ -194,10 +193,10 @@
                     synchronized (entry) {
                         entry.setState(FlowEntryState.PENDING_REMOVE);
                         // TODO: Should we notify only if it's "remote" event?
-                        notifyDelegate(FlowRuleBatchEvent.create(
-                                new FlowRuleBatchRequest(
-                                        Collections.<FlowEntry>emptyList(),
-                                        Arrays.<FlowEntry>asList(entry))));
+                        notifyDelegate(FlowRuleBatchEvent.requested(
+                                new FlowRuleBatchRequest(1, /* FIXME generate something */
+                                                         Collections.<FlowEntry>emptyList(),
+                                                         Arrays.<FlowEntry>asList(entry))));
                     }
                 }
             }
diff --git a/docs/external.xml b/docs/external.xml
new file mode 100644
index 0000000..959b473
--- /dev/null
+++ b/docs/external.xml
@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <prerequisites>
+        <maven>3.0.0</maven>
+    </prerequisites>
+
+    <parent>
+        <groupId>org.onlab.onos</groupId>
+        <artifactId>onos</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>onos-docs-external</artifactId>
+    <packaging>pom</packaging>
+
+    <description>ONOS Java API documentation</description>
+
+    <modules>
+        <module>..</module>
+    </modules>
+
+    <url>http://onlab.us/</url>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>2.10.1</version>
+                <configuration>
+                    <show>package</show>
+                    <excludePackageNames>org.onlab.thirdparty:*.impl:*.impl.*:org.onlab.onos.provider.*:org.onlab.onos.gui:org.onlab.onos.rest:org.onlab.onos.cli*:org.onlab.onos.tvue:org.onlab.onos.foo:org.onlab.onos.mobility:org.onlab.onos.proxyarp:org.onlab.onos.fwd:org.onlab.onos.ifwd:org.onlab.onos.optical:org.onlab.onos.config:org.onlab.onos.calendar:org.onlab.onos.sdnip*:org.onlab.onos.metrics</excludePackageNames>
+                    <docfilessubdirs>true</docfilessubdirs>
+                    <doctitle>ONOS Java API</doctitle>
+                    <groups>
+                        <group>
+                            <title>Network Model &amp; Services</title>
+                            <packages>
+                                org.onlab.onos:org.onlab.onos.*
+                            </packages>
+                        </group>
+                        <group>
+                            <title>Utilities</title>
+                            <packages>
+                                org.onlab.*
+                            </packages>
+                        </group>
+                    </groups>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>
diff --git a/docs/pom.xml b/docs/pom.xml
new file mode 100644
index 0000000..3a38f13
--- /dev/null
+++ b/docs/pom.xml
@@ -0,0 +1,85 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <prerequisites>
+        <maven>3.0.0</maven>
+    </prerequisites>
+
+    <parent>
+        <groupId>org.onlab.onos</groupId>
+        <artifactId>onos</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>onos-docs</artifactId>
+    <packaging>pom</packaging>
+
+    <description>ONOS Java API documentation</description>
+
+    <modules>
+        <module>..</module>
+    </modules>
+
+    <url>http://onlab.us/</url>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>2.10.1</version>
+                <configuration>
+                    <show>package</show>
+                    <docfilessubdirs>true</docfilessubdirs>
+                    <doctitle>ONOS Java API</doctitle>
+                    <groups>
+                        <group>
+                            <title>Network Model &amp; Services</title>
+                            <packages>
+                                org.onlab.onos:org.onlab.onos.*
+                            </packages>
+                        </group>
+                        <group>
+                            <title>Core Subsystems</title>
+                            <packages>
+                                org.onlab.onos.impl:org.onlab.onos.cluster.impl:org.onlab.onos.net.device.impl:org.onlab.onos.net.link.impl:org.onlab.onos.net.host.impl:org.onlab.onos.net.topology.impl:org.onlab.onos.net.packet.impl:org.onlab.onos.net.flow.impl:org.onlab.onos.store.trivial.*:org.onlab.onos.net.*.impl:org.onlab.onos.event.impl:org.onlab.onos.store.*:org.onlab.onos.net.intent.impl:org.onlab.onos.net.proxyarp.impl:org.onlab.onos.mastership.impl:org.onlab.onos.json:org.onlab.onos.json.*:org.onlab.onos.provider.host.impl:org.onlab.onos.provider.lldp.impl:org.onlab.onos.net.statistic.impl
+                            </packages>
+                        </group>
+                        <group>
+                            <title>OpenFlow Providers &amp; Controller
+                            </title>
+                            <packages>
+                                org.onlab.onos.provider.of.*:org.onlab.onos.openflow.*
+                            </packages>
+                        </group>
+                        <group>
+                            <title>Utilities</title>
+                            <packages>
+                                org.onlab.*
+                            </packages>
+                        </group>
+                        <group>
+                            <title>GUI, REST &amp; Command-Line</title>
+                            <packages>
+                                org.onlab.onos.gui:org.onlab.onos.rest:org.onlab.onos.cli:org.onlab.onos.gui.*:org.onlab.onos.rest.*:org.onlab.onos.cli.*
+                            </packages>
+                        </group>
+                        <group>
+                            <title>Sample Applications</title>
+                            <packages>
+                                org.onlab.onos.tvue:org.onlab.onos.fwd:org.onlab.onos.ifwd:org.onlab.onos.mobility:org.onlab.onos.proxyarp:org.onlab.onos.foo:org.onlab.onos.calendar:org.onlab.onos.sdnip:org.onlab.onos.sdnip.*:org.onlab.onos.optical:org.onlab.onos.optical.*:org.onlab.onos.metrics.*:org.onlab.onos.config
+                            </packages>
+                        </group>
+                    </groups>
+                    <excludePackageNames>org.onlab.thirdparty
+                    </excludePackageNames>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>
diff --git a/src/main/javadoc/doc-files/onos-subsystem.png b/docs/src/main/javadoc/doc-files/onos-subsystem.png
similarity index 100%
rename from src/main/javadoc/doc-files/onos-subsystem.png
rename to docs/src/main/javadoc/doc-files/onos-subsystem.png
Binary files differ
diff --git a/src/main/javadoc/doc-files/onos-tiers.png b/docs/src/main/javadoc/doc-files/onos-tiers.png
similarity index 100%
rename from src/main/javadoc/doc-files/onos-tiers.png
rename to docs/src/main/javadoc/doc-files/onos-tiers.png
Binary files differ
diff --git a/src/main/javadoc/overview.html b/docs/src/main/javadoc/overview.html
similarity index 100%
rename from src/main/javadoc/overview.html
rename to docs/src/main/javadoc/overview.html
diff --git a/features/features.xml b/features/features.xml
index e363094..be9110b 100644
--- a/features/features.xml
+++ b/features/features.xml
@@ -35,7 +35,7 @@
         <bundle>mvn:io.netty/netty-transport-native-epoll/4.0.23.Final</bundle>
         <bundle>mvn:commons-pool/commons-pool/1.6</bundle>
 
-        <bundle>mvn:com.hazelcast/hazelcast/3.3</bundle>
+        <bundle>mvn:com.hazelcast/hazelcast/3.3.2</bundle>
         <bundle>mvn:io.dropwizard.metrics/metrics-core/3.1.0</bundle>
         <bundle>mvn:io.dropwizard.metrics/metrics-json/3.1.0</bundle>
         <bundle>mvn:com.eclipsesource.minimal-json/minimal-json/0.9.1</bundle>
diff --git a/pom.xml b/pom.xml
index 8aa5ce4..ce02451 100644
--- a/pom.xml
+++ b/pom.xml
@@ -4,6 +4,10 @@
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
+    <prerequisites>
+        <maven>3.0.0</maven>
+    </prerequisites>
+
     <groupId>org.onlab.onos</groupId>
     <artifactId>onos</artifactId>
     <packaging>pom</packaging>
@@ -28,7 +32,6 @@
 
     <licenses>
         <license>
-            <!-- TODO: Is this really our license scheme? -->
             <name>Apache License, Version 2.0</name>
             <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
         </license>
@@ -192,7 +195,7 @@
             <dependency>
                 <groupId>com.hazelcast</groupId>
                 <artifactId>hazelcast</artifactId>
-                <version>3.3</version>
+                <version>3.3.2</version>
             </dependency>
             <dependency>
                 <groupId>com.eclipsesource.minimal-json</groupId>
@@ -528,59 +531,6 @@
                     </execution>
                 </executions>
             </plugin>
-
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-javadoc-plugin</artifactId>
-                <version>2.10.1</version>
-                <configuration>
-                    <show>package</show>
-                    <docfilessubdirs>true</docfilessubdirs>
-                    <doctitle>ONOS Java API</doctitle>
-                    <groups>
-                        <group>
-                            <title>Network Model &amp; Services</title>
-                            <packages>
-                                org.onlab.onos:org.onlab.onos.*
-                            </packages>
-                        </group>
-                        <group>
-                            <title>Core Subsystems</title>
-                            <packages>
-                                org.onlab.onos.impl:org.onlab.onos.cluster.impl:org.onlab.onos.net.device.impl:org.onlab.onos.net.link.impl:org.onlab.onos.net.host.impl:org.onlab.onos.net.topology.impl:org.onlab.onos.net.packet.impl:org.onlab.onos.net.flow.impl:org.onlab.onos.store.trivial.*:org.onlab.onos.net.*.impl:org.onlab.onos.event.impl:org.onlab.onos.store.*:org.onlab.onos.net.intent.impl:org.onlab.onos.net.proxyarp.impl:org.onlab.onos.mastership.impl:org.onlab.onos.json:org.onlab.onos.json.*:org.onlab.onos.provider.host.impl:org.onlab.onos.provider.lldp.impl:org.onlab.onos.net.statistic.impl
-                            </packages>
-                        </group>
-                        <group>
-                            <title>OpenFlow Providers &amp; Controller
-                            </title>
-                            <packages>
-                                org.onlab.onos.provider.of.*:org.onlab.onos.openflow.*
-                            </packages>
-                        </group>
-                        <group>
-                            <title>Utilities</title>
-                            <packages>
-                                org.onlab.*
-                            </packages>
-                        </group>
-                        <group>
-                            <title>GUI, REST &amp; Command-Line</title>
-                            <packages>
-                                org.onlab.onos.gui:org.onlab.onos.rest:org.onlab.onos.cli:org.onlab.onos.gui.*:org.onlab.onos.rest.*:org.onlab.onos.cli.*
-                            </packages>
-                        </group>
-                        <group>
-                            <title>Sample Applications</title>
-                            <packages>
-                                org.onlab.onos.tvue:org.onlab.onos.fwd:org.onlab.onos.ifwd:org.onlab.onos.mobility:org.onlab.onos.proxyarp:org.onlab.onos.foo:org.onlab.onos.calendar:org.onlab.onos.sdnip:org.onlab.onos.sdnip.*:org.onlab.onos.optical:org.onlab.onos.optical.*:org.onlab.onos.metrics.*
-                            </packages>
-                        </group>
-                    </groups>
-                    <excludePackageNames>org.onlab.thirdparty
-                    </excludePackageNames>
-                </configuration>
-            </plugin>
-
         </plugins>
     </build>
 
@@ -607,10 +557,6 @@
                     </rulesets>
                 </configuration>
             </plugin>
-
         </plugins>
     </reporting>
-    <prerequisites>
-        <maven>3.0.0</maven>
-    </prerequisites>
 </project>
diff --git a/tools/build/onos-build b/tools/build/onos-build
index cf2ebe4..2f31eeb 100755
--- a/tools/build/onos-build
+++ b/tools/build/onos-build
@@ -6,5 +6,4 @@
 [ ! -d "$ONOS_ROOT" ] && echo "ONOS_ROOT is not defined" >&2 && exit 1
 . $ONOS_ROOT/tools/build/envDefaults
 
-cd $ONOS_ROOT
-mvn clean install && mvn javadoc:aggregate
+cd $ONOS_ROOT && mvn clean install && cd docs && mvn javadoc:aggregate
diff --git a/utils/misc/src/main/java/org/onlab/metrics/EventMetric.java b/utils/misc/src/main/java/org/onlab/metrics/EventMetric.java
new file mode 100644
index 0000000..464a123
--- /dev/null
+++ b/utils/misc/src/main/java/org/onlab/metrics/EventMetric.java
@@ -0,0 +1,103 @@
+package org.onlab.metrics;
+
+import com.codahale.metrics.Gauge;
+import com.codahale.metrics.Meter;
+
+/**
+ * Metric measurements for events.
+ */
+public class EventMetric {
+    private static final String GAUGE_TIMESTAMP_NAME = "Timestamp.EpochMs";
+    private static final String METER_RATE_NAME = "Rate";
+
+    private final MetricsService metricsService;
+    private final String componentName;
+    private final String featureName;
+
+    private MetricsComponent metricsComponent;
+    private MetricsFeature metricsFeature;
+
+    private volatile long lastEventTimestampEpochMs = 0;
+    private Gauge<Long> lastEventTimestampGauge;
+    private Meter eventRateMeter;
+
+    /**
+     * Constructor.
+     *
+     * @param metricsService the Metrics Service to use for Metrics
+     * registration and deregistration
+     * @param componentName the Metrics Component Name to use for Metrics
+     * registration and deregistration
+     * @param featureName the Metrics Feature Name to use for Metrics
+     * registration and deregistration
+     */
+    public EventMetric(MetricsService metricsService, String componentName,
+                       String featureName) {
+        this.metricsService = metricsService;
+        this.componentName = componentName;
+        this.featureName = featureName;
+    }
+
+    /**
+     * Registers the metrics.
+     */
+    public void registerMetrics() {
+        metricsComponent = metricsService.registerComponent(componentName);
+        metricsFeature = metricsComponent.registerFeature(featureName);
+
+        lastEventTimestampEpochMs = 0;
+        lastEventTimestampGauge =
+            metricsService.registerMetric(metricsComponent,
+                                          metricsFeature,
+                                          GAUGE_TIMESTAMP_NAME,
+                                          new Gauge<Long>() {
+                                              @Override
+                                              public Long getValue() {
+                                                  return lastEventTimestampEpochMs;
+                                              }
+                                          });
+
+        eventRateMeter = metricsService.createMeter(metricsComponent,
+                                                    metricsFeature,
+                                                    METER_RATE_NAME);
+    }
+
+    /**
+     * Removes the metrics.
+     */
+    public void removeMetrics() {
+        lastEventTimestampEpochMs = 0;
+        metricsService.removeMetric(metricsComponent,
+                                    metricsFeature,
+                                    GAUGE_TIMESTAMP_NAME);
+        metricsService.removeMetric(metricsComponent,
+                                    metricsFeature,
+                                    METER_RATE_NAME);
+    }
+
+    /**
+     * Updates the metric measurements for a single event.
+     */
+    public void eventReceived() {
+        lastEventTimestampEpochMs = System.currentTimeMillis();
+        eventRateMeter.mark(1);
+    }
+
+    /**
+     * Gets the last event timestamp Gauge (ms from the Epoch).
+     *
+     * @return the last event timestamp Gauge (ms from the Epoch)
+     */
+    public Gauge<Long> lastEventTimestampGauge() {
+        return lastEventTimestampGauge;
+    }
+
+    /**
+     * Gets the event rate meter.
+     *
+     * @return the event rate meter
+     */
+    public Meter eventRateMeter() {
+        return eventRateMeter;
+    }
+}
diff --git a/web/gui/src/main/webapp/network.js b/web/gui/src/main/webapp/network.js
index 80d11b7..ef190e7 100644
--- a/web/gui/src/main/webapp/network.js
+++ b/web/gui/src/main/webapp/network.js
@@ -10,17 +10,33 @@
     var api = onos.api;
 
     var config = {
-            layering: false,
+            options: {
+                layering: false,
+                collisionPrevention: true
+            },
             jsonUrl: 'network.json',
             iconUrl: {
-                pkt: 'pkt.png',
-                opt: 'opt.png'
+                logo: 'img/onos-logo.tiff',
+                device: 'img/device.png',
+                host: 'img/host.png',
+                pkt: 'img/pkt.png',
+                opt: 'img/opt.png'
             },
             mastHeight: 32,
             force: {
-                linkDistance: 240,
-                linkStrength: 0.8,
-                charge: -400,
+                note: 'node.class or link.class is used to differentiate',
+                linkDistance: {
+                    infra: 240,
+                    host: 100
+                },
+                linkStrength: {
+                    infra: 1.0,
+                    host: 0.4
+                },
+                charge: {
+                    device: -800,
+                    host: -400
+                },
                 ticksWithoutCollisions: 50,
                 marginLR: 20,
                 marginTB: 20,
@@ -37,12 +53,21 @@
                 marginLR: 3,
                 marginTB: 2
             },
+            icons: {
+                w: 32,
+                h: 32,
+                xoff: -12,
+                yoff: -10
+            },
             constraints: {
                 ypos: {
-                    pkt: 0.3,
-                    opt: 0.7
+                    host: 0.15,
+                    switch: 0.3,
+                    roadm: 0.7
                 }
-            }
+            },
+            hostLinkWidth: 1.0,
+            mouseOutTimerDelayMs: 120
         },
         view = {},
         network = {},
@@ -104,14 +129,23 @@
         var nw = network.forceWidth,
             nh = network.forceHeight;
 
-        network.data.nodes.forEach(function(n) {
+        function yPosConstraintForNode(n) {
+            return config.constraints.ypos[n.type || 'host'];
+        }
+
+        // Note that both 'devices' and 'hosts' get mapped into the nodes array
+
+        // first, the devices...
+        network.data.devices.forEach(function(n) {
             var ypc = yPosConstraintForNode(n),
                 ix = Math.random() * 0.6 * nw + 0.2 * nw,
                 iy = ypc * nh,
                 node = {
                     id: n.id,
+                    labels: n.labels,
+                    class: 'device',
+                    icon: 'device',
                     type: n.type,
-                    status: n.status,
                     x: ix,
                     y: iy,
                     constraint: {
@@ -123,21 +157,61 @@
             network.nodes.push(node);
         });
 
-        function yPosConstraintForNode(n) {
-            return config.constraints.ypos[n.type] || 0.5;
-        }
+        // then, the hosts...
+        network.data.hosts.forEach(function(n) {
+            var ypc = yPosConstraintForNode(n),
+                ix = Math.random() * 0.6 * nw + 0.2 * nw,
+                iy = ypc * nh,
+                node = {
+                    id: n.id,
+                    labels: n.labels,
+                    class: 'host',
+                    icon: 'host',
+                    type: n.type,
+                    x: ix,
+                    y: iy,
+                    constraint: {
+                        weight: 0.7,
+                        y: iy
+                    }
+                };
+            network.lookup[n.id] = node;
+            network.nodes.push(node);
+        });
 
 
+        // now, process the explicit links...
         network.data.links.forEach(function(n) {
             var src = network.lookup[n.src],
                 dst = network.lookup[n.dst],
                 id = src.id + "~" + dst.id;
 
             var link = {
+                class: 'infra',
                 id: id,
+                type: n.type,
+                width: n.linkWidth,
                 source: src,
                 target: dst,
-                strength: config.force.linkStrength
+                strength: config.force.linkStrength.infra
+            };
+            network.links.push(link);
+        });
+
+        // finally, infer host links...
+        network.data.hosts.forEach(function(n) {
+            var src = network.lookup[n.id],
+                dst = network.lookup[n.cp.device],
+                id = src.id + "~" + dst.id;
+
+            var link = {
+                class: 'host',
+                id: id,
+                type: 'hostLink',
+                width: config.hostLinkWidth,
+                source: src,
+                target: dst,
+                strength: config.force.linkStrength.host
             };
             network.links.push(link);
         });
@@ -145,13 +219,15 @@
 
     function createLayout() {
 
+        var cfg = config.force;
+
         network.force = d3.layout.force()
+            .size([network.forceWidth, network.forceHeight])
             .nodes(network.nodes)
             .links(network.links)
-            .linkStrength(function(d) { return d.strength; })
-            .size([network.forceWidth, network.forceHeight])
-            .linkDistance(config.force.linkDistance)
-            .charge(config.force.charge)
+            .linkStrength(function(d) { return cfg.linkStrength[d.class]; })
+            .linkDistance(function(d) { return cfg.linkDistance[d.class]; })
+            .charge(function(d) { return cfg.charge[d.class]; })
             .on('tick', tick);
 
         network.svg = d3.select('#view').append('svg')
@@ -205,9 +281,10 @@
         network.link = network.svg.append('g').selectAll('.link')
             .data(network.force.links(), function(d) {return d.id})
             .enter().append('line')
-            .attr('class', 'link');
+            .attr('class', function(d) {return 'link ' + d.class});
 
-        // TODO: drag behavior
+
+        // == define node drag behavior...
         network.draggedThreshold = d3.scale.linear()
             .domain([0, 0.1])
             .range([5, 20])
@@ -258,7 +335,11 @@
             .data(network.force.nodes(), function(d) {return d.id})
             .enter().append('g')
             .attr('class', function(d) {
-                return 'node ' + d.type;
+                var cls = 'node ' + d.class;
+                if (d.type) {
+                    cls += ' ' + d.type;
+                }
+                return cls;
             })
             .attr('transform', function(d) {
                 return translate(d.x, d.y);
@@ -281,29 +362,32 @@
                     }
                     network.mouseoutTimeout = setTimeout(function() {
                         highlightObject(null);
-                    }, 160);
+                    }, config.mouseOutTimerDelayMs);
                 }
             });
 
         network.nodeRect = network.node.append('rect')
             .attr('rx', 5)
-            .attr('ry', 5)
-            .attr('width', 126)
-            .attr('height', 40);
+            .attr('ry', 5);
+        // note that width/height are adjusted to fit the label text
 
         network.node.each(function(d) {
             var node = d3.select(this),
                 rect = node.select('rect'),
-                img = node.append('svg:image')
-                    .attr('x', -16)
-                    .attr('y', -16)
-                    .attr('width', 32)
-                    .attr('height', 32)
-                    .attr('xlink:href', iconUrl(d)),
+                icon = iconUrl(d),
                 text = node.append('text')
                     .text(d.id)
-                    .attr('dy', '1.1em'),
-                dummy;
+                    .attr('dy', '1.1em');
+
+            if (icon) {
+                var cfg = config.icons;
+                node.append('svg:image')
+                    .attr('width', cfg.w)
+                    .attr('height', cfg.h)
+                    .attr('xlink:href', icon);
+                // note, icon relative positioning (x,y) is done after we have
+                // adjusted the bounds of the rectangle...
+            }
 
         });
 
@@ -352,7 +436,8 @@
                     .attr('height', bounds.y2 - bounds.y1);
 
                 node.select('image')
-                    .attr('x', bounds.x1);
+                    .attr('x', bounds.x1 + config.icons.xoff)
+                    .attr('y', bounds.y1 + config.icons.yoff);
 
                 d.extent = {
                     left: bounds.x1 - lab.marginLR,
@@ -384,7 +469,7 @@
     }
 
     function iconUrl(d) {
-        return config.iconUrl[d.type];
+        return config.iconUrl[d.icon];
     }
 
     function translate(x, y) {
@@ -440,7 +525,7 @@
     function tick(e) {
         network.numTicks++;
 
-        if (config.layering) {
+        if (config.options.layering) {
             // adjust the y-coord of each node, based on y-pos constraints
             network.nodes.forEach(function (n) {
                 var z = e.alpha * n.constraint.weight;
@@ -450,7 +535,7 @@
             });
         }
 
-        if (network.preventCollisions) {
+        if (config.options.collisionPrevention && network.preventCollisions) {
             preventCollisions();
         }
 
diff --git a/web/gui/src/main/webapp/network.json b/web/gui/src/main/webapp/network.json
index b4f1b6e..c43e0ef 100644
--- a/web/gui/src/main/webapp/network.json
+++ b/web/gui/src/main/webapp/network.json
@@ -1,56 +1,163 @@
 {
-    "id": "network-v1",
     "meta": {
-        "__comment_1__": "This is sample data for developing the ONOS UI",
-        "foo": "bar",
-        "zoo": "goo"
+        "comments": [
+            "This is sample data for developing the ONOS UI (network view)",
+            " in a standalone mode (no server required).",
+            " Eventually, we will wire this up to live data",
+            " from the server, via a websocket.",
+            "",
+            "Note that this is just a first-draft of the data --",
+            " additional fields will be added when they are needed."
+        ],
+        "otherMetaData": "can go here..."
     },
-    "nodes": [
+    "devices": [
         {
-            "id": "sample1",
-            "type": "opt",
-            "status": "good"
+            "id": "of:0000000000000001",
+            "labels": ["00:00:00:00:00:00:00:01", "of/::01", "opt-1"],
+            "type": "roadm"
         },
         {
-            "id": "00:00:00:00:00:00:00:02",
-            "type": "opt",
-            "status": "good"
+            "id": "of:0000000000000002",
+            "labels": ["00:00:00:00:00:00:00:02", "of/::02", "opt-2"],
+            "type": "roadm"
         },
         {
-            "id": "00:00:00:00:00:00:00:03",
-            "type": "opt",
-            "status": "good"
+            "id": "of:0000000000000003",
+            "labels": ["00:00:00:00:00:00:00:03", "of/::03", "opt-3"],
+            "type": "roadm"
         },
         {
-            "id": "00:00:00:00:00:00:00:04",
-            "type": "opt",
-            "status": "good"
+            "id": "of:0000000000000004",
+            "labels": ["00:00:00:00:00:00:00:04", "of/::04", "opt-4"],
+            "type": "roadm"
         },
         {
-            "id": "00:00:00:00:00:00:00:11",
-            "type": "pkt",
-            "status": "good"
+            "id": "of:0000000000000011",
+            "labels": ["00:00:00:00:00:00:00:11", "of/::11", "pkt-11"],
+            "type": "switch"
         },
         {
-            "id": "00:00:00:00:00:00:00:12",
-            "type": "pkt",
-            "status": "good"
+            "id": "of:0000000000000012",
+            "labels": ["00:00:00:00:00:00:00:12", "of/::12", "pkt-12"],
+            "type": "switch"
         },
         {
-            "id": "00:00:00:00:00:00:00:13",
-            "type": "pkt",
-            "status": "good"
+            "id": "of:0000000000000013",
+            "labels": ["00:00:00:00:00:00:00:13", "of/::13", "pkt-13"],
+            "type": "switch"
         }
     ],
+    "linkNotes": [
+        "even though we have 'directionality' (src/dst), each link is",
+        " considered to be bi-directional. Note that links between hosts",
+        " and edge switches are inferred from host information, and not",
+        " explicitly represented here."
+    ],
     "links": [
-        { "src": "sample1", "dst": "00:00:00:00:00:00:00:02" },
-        { "src": "sample1", "dst": "00:00:00:00:00:00:00:03" },
-        { "src": "sample1", "dst": "00:00:00:00:00:00:00:04" },
-        { "src": "00:00:00:00:00:00:00:02", "dst": "00:00:00:00:00:00:00:03" },
-        { "src": "00:00:00:00:00:00:00:02", "dst": "00:00:00:00:00:00:00:04" },
-        { "src": "00:00:00:00:00:00:00:03", "dst": "00:00:00:00:00:00:00:04" },
-        { "src": "00:00:00:00:00:00:00:13", "dst": "00:00:00:00:00:00:00:03" },
-        { "src": "00:00:00:00:00:00:00:12", "dst": "00:00:00:00:00:00:00:02" },
-        { "src": "00:00:00:00:00:00:00:11", "dst": "sample1" }
+        {
+            "src": "of:0000000000000001",
+            "dst": "of:0000000000000002",
+            "type": "optical",
+            "linkWidth": 1.5
+        },
+        {
+            "src": "of:0000000000000001",
+            "dst": "of:0000000000000003",
+            "type": "optical",
+            "linkWidth": 1.5
+        },
+        {
+            "src": "of:0000000000000001",
+            "dst": "of:0000000000000004",
+            "type": "optical",
+            "linkWidth": 1.5
+        },
+        {
+            "src": "of:0000000000000002",
+            "dst": "of:0000000000000003",
+            "type": "optical",
+            "linkWidth": 1.5
+        },
+        {
+            "src": "of:0000000000000002",
+            "dst": "of:0000000000000004",
+            "type": "optical",
+            "linkWidth": 1.5
+        },
+        {
+            "src": "of:0000000000000003",
+            "dst": "of:0000000000000004",
+            "type": "optical",
+            "linkWidth": 1.5
+        },
+        {
+            "src": "of:0000000000000013",
+            "dst": "of:0000000000000003",
+            "type": "direct",
+            "linkWidth": 1.0
+        },
+        {
+            "src": "of:0000000000000012",
+            "dst": "of:0000000000000002",
+            "type": "direct",
+            "linkWidth": 1.0
+        },
+        {
+            "src": "of:0000000000000011",
+            "dst": "of:0000000000000001",
+            "type": "direct",
+            "linkWidth": 1.0
+        }
+    ],
+    "hosts": [
+        {
+            "id": "00:60:d3:00:11:01/7",
+            "labels": ["00:60:d3:00:11:01/7", "Host-11-A"],
+            "cp" : {
+                "device": "of:0000000000000011",
+                "port": 6
+            }
+        },
+        {
+            "id": "00:60:d3:00:11:02/7",
+            "labels": ["00:60:d3:00:11:02/7", "Host-11-B"],
+            "cp" : {
+                "device": "of:0000000000000011",
+                "port": 8
+            }
+        },
+        {
+            "id": "00:60:d3:00:12:01/4",
+            "labels": ["00:60:d3:00:12:01/4", "Host-12-C"],
+            "cp" : {
+                "device": "of:0000000000000012",
+                "port": 12
+            }
+        },
+        {
+            "id": "00:60:d3:00:12:02/4",
+            "labels": ["00:60:d3:00:12:02/4", "Host-12-D"],
+            "cp" : {
+                "device": "of:0000000000000012",
+                "port": 13
+            }
+        },
+        {
+            "id": "00:60:d3:00:13:01/19",
+            "labels": ["00:60:d3:00:13:01/19", "Host-13-E"],
+            "cp" : {
+                "device": "of:0000000000000013",
+                "port": 7
+            }
+        },
+        {
+            "id": "00:60:d3:00:13:02/19",
+            "labels": ["00:60:d3:00:13:02/19", "Host-13-F"],
+            "cp" : {
+                "device": "of:0000000000000013",
+                "port": 8
+            }
+        }
     ]
 }
diff --git a/web/gui/src/main/webapp/onos.css b/web/gui/src/main/webapp/onos.css
index 340ae79..b2df75c 100644
--- a/web/gui/src/main/webapp/onos.css
+++ b/web/gui/src/main/webapp/onos.css
@@ -38,7 +38,7 @@
  * Network Graph elements ======================================
  */
 
-.link {
+svg .link {
     fill: none;
     stroke: #666;
     stroke-width: 1.5px;
@@ -56,7 +56,7 @@
     stroke-width: 1.5px;
 }
 
-.node rect {
+svg .node rect {
     stroke-width: 1.5px;
 
     transition: opacity 250ms;
@@ -64,13 +64,15 @@
     -moz-transition: opacity 250ms;
 }
 
-/*differentiate between packet and optical nodes*/
-svg .node.pkt rect {
-    fill: #77a;
+svg .node.device.roadm rect {
+    fill: #229;
+}
+svg .node.device.switch rect {
+    fill: #55f;
 }
 
-svg .node.opt rect {
-    fill: #7a7;
+svg .node.host rect {
+    fill: #787;
 }
 
 svg .node text {
@@ -121,15 +123,13 @@
 #frame {
     width: 100%;
     height: 100%;
-    background-color: #cdf;
+    background-color: #fff;
 }
 
 #mast {
     height: 32px;
-    background-color: #abe;
+    padding: 6px;
+    background-color: #ccc;
     vertical-align: baseline;
 }
 
-#main {
-    background-color: #99c;
-}
diff --git a/web/gui/src/main/webapp/opt.png b/web/gui/src/main/webapp/opt.png
deleted file mode 100644
index 2f2c88e..0000000
--- a/web/gui/src/main/webapp/opt.png
+++ /dev/null
Binary files differ
diff --git a/web/gui/src/main/webapp/pkt.png b/web/gui/src/main/webapp/pkt.png
deleted file mode 100644
index 1b1d5a3..0000000
--- a/web/gui/src/main/webapp/pkt.png
+++ /dev/null
Binary files differ