diff --git a/core/api/src/main/java/org/onlab/onos/net/topology/TopologyService.java b/core/api/src/main/java/org/onlab/onos/net/topology/TopologyService.java
index 36ee666..7c6be33 100644
--- a/core/api/src/main/java/org/onlab/onos/net/topology/TopologyService.java
+++ b/core/api/src/main/java/org/onlab/onos/net/topology/TopologyService.java
@@ -20,6 +20,13 @@
     Topology currentTopology();
 
     /**
+     * Indicates whether the specified topology is the latest or not.
+     * @param topology topology descriptor
+     * @return true if the topology is the most recent; false otherwise
+     */
+    boolean isLatest(Topology topology);
+
+    /**
      * Returns the set of clusters in the specified topology.
      *
      * @param topology topology descriptor
diff --git a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DefaultTopology.java b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DefaultTopology.java
new file mode 100644
index 0000000..cb55819
--- /dev/null
+++ b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DefaultTopology.java
@@ -0,0 +1,64 @@
+package org.onlab.onos.net.trivial.impl;
+
+import org.onlab.onos.net.AbstractModel;
+import org.onlab.onos.net.provider.ProviderId;
+import org.onlab.onos.net.topology.Topology;
+
+/**
+ * Default implementation of the topology descriptor. This carries the
+ * backing topology data.
+ */
+public class DefaultTopology extends AbstractModel implements Topology {
+
+    private final long time;
+    private final int clusterCount;
+    private final int deviceCount;
+    private final int linkCount;
+    private final int pathCount;
+
+    /**
+     * Creates a topology descriptor attributed to the specified provider.
+     *
+     * @param providerId   identity of the provider
+     * @param time         creation time in system nanos
+     * @param clusterCount number of clusters
+     * @param deviceCount  number of devices
+     * @param linkCount    number of links
+     * @param pathCount    number of pre-computed paths
+     */
+    DefaultTopology(ProviderId providerId, long time, int clusterCount,
+                    int deviceCount, int linkCount, int pathCount) {
+        super(providerId);
+        this.time = time;
+        this.clusterCount = clusterCount;
+        this.deviceCount = deviceCount;
+        this.linkCount = linkCount;
+        this.pathCount = pathCount;
+    }
+
+    @Override
+    public long time() {
+        return time;
+    }
+
+    @Override
+    public int clusterCount() {
+        return clusterCount;
+    }
+
+    @Override
+    public int deviceCount() {
+        return deviceCount;
+    }
+
+    @Override
+    public int linkCount() {
+        return linkCount;
+    }
+
+    @Override
+    public int pathCount() {
+        return pathCount;
+    }
+
+}
diff --git a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
index c322b70..135edd9 100644
--- a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
+++ b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
@@ -150,7 +150,8 @@
     }
 
     // Personalized device provider service issued to the supplied provider.
-    private class InternalDeviceProviderService extends AbstractProviderService<DeviceProvider>
+    private class InternalDeviceProviderService
+            extends AbstractProviderService<DeviceProvider>
             implements DeviceProviderService {
 
         InternalDeviceProviderService(DeviceProvider provider) {
diff --git a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java
index 05557c5..3152209 100644
--- a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java
+++ b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleHostManager.java
@@ -158,7 +158,7 @@
 
     // Posts the specified event to the local event dispatcher.
     private void post(HostEvent event) {
-        if (event != null && eventDispatcher != null) {
+        if (event != null) {
             eventDispatcher.post(event);
         }
     }
diff --git a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java
index d900c5b..1930ea1 100644
--- a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java
+++ b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleLinkManager.java
@@ -36,8 +36,8 @@
 @Component(immediate = true)
 @Service
 public class SimpleLinkManager
-extends AbstractProviderRegistry<LinkProvider, LinkProviderService>
-implements LinkService, LinkAdminService, LinkProviderRegistry {
+        extends AbstractProviderRegistry<LinkProvider, LinkProviderService>
+        implements LinkService, LinkAdminService, LinkProviderRegistry {
 
     private static final String DEVICE_ID_NULL = "Device ID cannot be null";
     private static final String LINK_DESC_NULL = "Link description cannot be null";
@@ -46,7 +46,7 @@
     private final Logger log = getLogger(getClass());
 
     private final AbstractListenerRegistry<LinkEvent, LinkListener>
-    listenerRegistry = new AbstractListenerRegistry<>();
+            listenerRegistry = new AbstractListenerRegistry<>();
 
     private final SimpleLinkStore store = new SimpleLinkStore();
 
@@ -79,7 +79,7 @@
     public Set<Link> getDeviceLinks(DeviceId deviceId) {
         checkNotNull(deviceId, DEVICE_ID_NULL);
         return Sets.union(store.getDeviceEgressLinks(deviceId),
-                store.getDeviceIngressLinks(deviceId));
+                          store.getDeviceIngressLinks(deviceId));
     }
 
     @Override
@@ -98,7 +98,7 @@
     public Set<Link> getLinks(ConnectPoint connectPoint) {
         checkNotNull(connectPoint, CONNECT_POINT_NULL);
         return Sets.union(store.getEgressLinks(connectPoint),
-                store.getIngressLinks(connectPoint));
+                          store.getIngressLinks(connectPoint));
     }
 
     @Override
@@ -146,8 +146,9 @@
     }
 
     // Personalized link provider service issued to the supplied provider.
-    private class InternalLinkProviderService extends AbstractProviderService<LinkProvider>
-    implements LinkProviderService {
+    private class InternalLinkProviderService
+            extends AbstractProviderService<LinkProvider>
+            implements LinkProviderService {
 
         InternalLinkProviderService(LinkProvider provider) {
             super(provider);
@@ -157,27 +158,31 @@
         public void linkDetected(LinkDescription linkDescription) {
             checkNotNull(linkDescription, LINK_DESC_NULL);
             checkValidity();
-            log.debug("Link {} detected", linkDescription);
             LinkEvent event = store.createOrUpdateLink(provider().id(),
-                    linkDescription);
-            post(event);
+                                                       linkDescription);
+            if (event != null) {
+                log.debug("Link {} detected", linkDescription);
+                post(event);
+            }
         }
 
         @Override
         public void linkVanished(LinkDescription linkDescription) {
             checkNotNull(linkDescription, LINK_DESC_NULL);
             checkValidity();
-            log.info("Link {} vanished", linkDescription);
             LinkEvent event = store.removeLink(linkDescription.src(),
-                    linkDescription.dst());
-            post(event);
+                                               linkDescription.dst());
+            if (event != null) {
+                log.info("Link {} vanished", linkDescription);
+                post(event);
+            }
         }
 
         @Override
         public void linksVanished(ConnectPoint connectPoint) {
             checkNotNull(connectPoint, "Connect point cannot be null");
             checkValidity();
-            log.info("Link for connection point {} vanished", connectPoint);
+            log.info("Links for connection point {} vanished", connectPoint);
             removeLinks(getLinks(connectPoint));
         }
 
@@ -185,7 +190,7 @@
         public void linksVanished(DeviceId deviceId) {
             checkNotNull(deviceId, DEVICE_ID_NULL);
             checkValidity();
-            log.info("Link for device {} vanished", deviceId);
+            log.info("Links for device {} vanished", deviceId);
             removeLinks(getDeviceLinks(deviceId));
         }
     }
@@ -200,7 +205,7 @@
 
     // Posts the specified event to the local event dispatcher.
     private void post(LinkEvent event) {
-        if (event != null && eventDispatcher != null) {
+        if (event != null) {
             eventDispatcher.post(event);
         }
     }
diff --git a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyManager.java b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyManager.java
index 1e95598..4188cac 100644
--- a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyManager.java
+++ b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyManager.java
@@ -72,25 +72,26 @@
     }
 
     @Override
-    protected TopologyProviderService createProviderService(TopologyProvider provider) {
-        return new InternalTopologyProviderService(provider);
+    public Topology currentTopology() {
+        return store.currentTopology();
     }
 
     @Override
-    public Topology currentTopology() {
-        return null;
+    public boolean isLatest(Topology topology) {
+        checkNotNull(topology, TOPOLOGY_NULL);
+        return store.isLatest(topology);
     }
 
     @Override
     public Set<TopologyCluster> getClusters(Topology topology) {
         checkNotNull(topology, TOPOLOGY_NULL);
-        return null;
+        return store.getClusters(topology);
     }
 
     @Override
     public Graph<TopoVertex, TopoEdge> getGraph(Topology topology) {
         checkNotNull(topology, TOPOLOGY_NULL);
-        return null;
+        return store.getGraph(topology);
     }
 
     @Override
@@ -98,7 +99,7 @@
         checkNotNull(topology, TOPOLOGY_NULL);
         checkNotNull(src, DEVICE_ID_NULL);
         checkNotNull(dst, DEVICE_ID_NULL);
-        return null;
+        return store.getPaths(topology, src, dst);
     }
 
     @Override
@@ -107,21 +108,21 @@
         checkNotNull(src, DEVICE_ID_NULL);
         checkNotNull(dst, DEVICE_ID_NULL);
         checkNotNull(weight, "Link weight cannot be null");
-        return null;
+        return store.getPaths(topology, src, dst, weight);
     }
 
     @Override
     public boolean isInfrastructure(Topology topology, ConnectPoint connectPoint) {
         checkNotNull(topology, TOPOLOGY_NULL);
         checkNotNull(connectPoint, CONNECTION_POINT_NULL);
-        return false;
+        return store.isInfrastructure(topology, connectPoint);
     }
 
     @Override
     public boolean isInBroadcastTree(Topology topology, ConnectPoint connectPoint) {
         checkNotNull(topology, TOPOLOGY_NULL);
         checkNotNull(connectPoint, CONNECTION_POINT_NULL);
-        return false;
+        return store.isInBroadcastTree(topology, connectPoint);
     }
 
     @Override
@@ -135,6 +136,11 @@
     }
 
     // Personalized host provider service issued to the supplied provider.
+    @Override
+    protected TopologyProviderService createProviderService(TopologyProvider provider) {
+        return new InternalTopologyProviderService(provider);
+    }
+
     private class InternalTopologyProviderService
             extends AbstractProviderService<TopologyProvider>
             implements TopologyProviderService {
@@ -147,8 +153,12 @@
         public void topologyChanged(TopologyDescription topoDescription,
                                     List<Event> reasons) {
             checkNotNull(topoDescription, "Topology description cannot be null");
-            log.info("Topology changed due to: {}",
-                     reasons == null ? "initial compute" : reasons);
+            TopologyEvent event = store.updateTopology(topoDescription, reasons);
+            if (event != null) {
+                log.info("Topology changed due to: {}",
+                         reasons == null ? "initial compute" : reasons);
+                eventDispatcher.post(event);
+            }
         }
     }
 
diff --git a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyStore.java b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyStore.java
index 1a54cad..1ff0712 100644
--- a/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyStore.java
+++ b/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleTopologyStore.java
@@ -1,8 +1,124 @@
 package org.onlab.onos.net.trivial.impl;
 
+import org.onlab.graph.Graph;
+import org.onlab.onos.event.Event;
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.topology.LinkWeight;
+import org.onlab.onos.net.topology.TopoEdge;
+import org.onlab.onos.net.topology.TopoVertex;
+import org.onlab.onos.net.topology.Topology;
+import org.onlab.onos.net.topology.TopologyCluster;
+import org.onlab.onos.net.topology.TopologyDescription;
+import org.onlab.onos.net.topology.TopologyEvent;
+
+import java.util.List;
+import java.util.Set;
+
 /**
  * Manages inventory of topology snapshots using trivial in-memory
  * implementation.
  */
 public class SimpleTopologyStore {
+
+    private volatile DefaultTopology current;
+
+    /**
+     * Returns the current topology snapshot.
+     *
+     * @return current topology descriptor
+     */
+    Topology currentTopology() {
+        return current;
+    }
+
+    /**
+     * Indicates whether the topology is the latest.
+     * @param topology topology descriptor
+     * @return true if topology is the most recent one
+     */
+    boolean isLatest(Topology topology) {
+        return topology == current;
+    }
+
+    /**
+     * Returns the set of topology SCC clusters.
+     *
+     * @param topology topology descriptor
+     * @return set of clusters
+     */
+    Set<TopologyCluster> getClusters(Topology topology) {
+        return null;
+    }
+
+    /**
+     * Returns the immutable graph view of the current topology.
+     *
+     * @param topology topology descriptor
+     * @return graph view
+     */
+    Graph<TopoVertex, TopoEdge> getGraph(Topology topology) {
+        return null;
+    }
+
+    /**
+     * Returns the set of pre-computed shortest paths between src and dest.
+     *
+     * @param topology topology descriptor
+     * @param src      source device
+     * @param dst      destination device
+     * @return set of shortest paths
+     */
+    Set<Path> getPaths(Topology topology, DeviceId src, DeviceId dst) {
+        return null;
+    }
+
+    /**
+     * Computes and returns the set of shortest paths between src and dest.
+     *
+     * @param topology topology descriptor
+     * @param src      source device
+     * @param dst      destination device
+     * @param weight   link weight function
+     * @return set of shortest paths
+     */
+    Set<Path> getPaths(Topology topology, DeviceId src, DeviceId dst,
+                       LinkWeight weight) {
+        return null;
+    }
+
+    /**
+     * Indicates whether the given connect point is part of the network fabric.
+     *
+     * @param topology     topology descriptor
+     * @param connectPoint connection point
+     * @return true if infrastructure; false otherwise
+     */
+    boolean isInfrastructure(Topology topology, ConnectPoint connectPoint) {
+        return false;
+    }
+
+    /**
+     * Indicates whether the given connect point is part of the broadcast tree.
+     *
+     * @param topology     topology descriptor
+     * @param connectPoint connection point
+     * @return true if in broadcast tree; false otherwise
+     */
+    boolean isInBroadcastTree(Topology topology, ConnectPoint connectPoint) {
+        return false;
+    }
+
+    /**
+     * Generates a new topology snapshot from the specified description.
+     *
+     * @param topoDescription topology description
+     * @param reasons         list of events that triggered the update
+     * @return topology update event or null if the description is old
+     */
+    TopologyEvent updateTopology(TopologyDescription topoDescription, List<Event> reasons) {
+        return null;
+    }
+
 }