diff --git a/core/api/src/main/java/org/onlab/onos/net/intent/constraint/BooleanConstraint.java b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/BooleanConstraint.java
index 97c5695..4e9fc9a 100644
--- a/core/api/src/main/java/org/onlab/onos/net/intent/constraint/BooleanConstraint.java
+++ b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/BooleanConstraint.java
@@ -52,7 +52,7 @@
     @Override
     public boolean validate(Path path, LinkResourceService resourceService) {
         for (Link link : path.links()) {
-            if (isValid(link, resourceService)) {
+            if (!isValid(link, resourceService)) {
                 return false;
             }
         }
diff --git a/core/api/src/main/java/org/onlab/onos/net/intent/constraint/ObstacleConstraint.java b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/ObstacleConstraint.java
index 3ed3fae..6d73fc2 100644
--- a/core/api/src/main/java/org/onlab/onos/net/intent/constraint/ObstacleConstraint.java
+++ b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/ObstacleConstraint.java
@@ -19,7 +19,6 @@
 import com.google.common.collect.ImmutableSet;
 import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.Link;
-import org.onlab.onos.net.Path;
 import org.onlab.onos.net.resource.LinkResourceService;
 
 import java.util.Objects;
@@ -49,17 +48,6 @@
     }
 
     @Override
-    public boolean validate(Path path, LinkResourceService resourceService) {
-        for (Link link : path.links()) {
-            if (!isValid(link, resourceService)) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    @Override
     public int hashCode() {
         return Objects.hash(obstacles);
     }
diff --git a/core/api/src/test/java/org/onlab/onos/net/NetTestTools.java b/core/api/src/test/java/org/onlab/onos/net/NetTestTools.java
index 8d2a61b..5f8920b 100644
--- a/core/api/src/test/java/org/onlab/onos/net/NetTestTools.java
+++ b/core/api/src/test/java/org/onlab/onos/net/NetTestTools.java
@@ -15,6 +15,8 @@
  */
 package org.onlab.onos.net;
 
+import org.onlab.onos.TestApplicationId;
+import org.onlab.onos.core.ApplicationId;
 import org.onlab.onos.net.provider.ProviderId;
 import org.onlab.packet.ChassisId;
 import org.onlab.packet.IpAddress;
@@ -39,6 +41,7 @@
     }
 
     public static final ProviderId PID = new ProviderId("of", "foo");
+    public static final ApplicationId APP_ID = new TestApplicationId("foo");
 
     // Short-hand for producing a device id from a string
     public static DeviceId did(String id) {
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java
index 461f670..9c196a2 100644
--- a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java
@@ -67,7 +67,7 @@
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected LinkResourceService resourceService;
 
-    private ApplicationId appId;
+    protected ApplicationId appId;
 
     @Activate
     public void activate() {
diff --git a/core/net/src/test/java/org/onlab/onos/net/intent/IntentTestsMocks.java b/core/net/src/test/java/org/onlab/onos/net/intent/IntentTestsMocks.java
index 6331706..e0fe09e 100644
--- a/core/net/src/test/java/org/onlab/onos/net/intent/IntentTestsMocks.java
+++ b/core/net/src/test/java/org/onlab/onos/net/intent/IntentTestsMocks.java
@@ -16,23 +16,39 @@
 package org.onlab.onos.net.intent;
 
 import static org.onlab.onos.net.NetTestTools.createPath;
+import static org.onlab.onos.net.NetTestTools.link;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
 
+import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.ElementId;
+import org.onlab.onos.net.Link;
 import org.onlab.onos.net.Path;
 import org.onlab.onos.net.flow.TrafficSelector;
 import org.onlab.onos.net.flow.TrafficTreatment;
 import org.onlab.onos.net.flow.criteria.Criterion;
 import org.onlab.onos.net.flow.criteria.Criterion.Type;
 import org.onlab.onos.net.flow.instructions.Instruction;
+import org.onlab.onos.net.resource.BandwidthResourceRequest;
+import org.onlab.onos.net.resource.LambdaResourceRequest;
+import org.onlab.onos.net.resource.LinkResourceAllocations;
+import org.onlab.onos.net.resource.LinkResourceRequest;
+import org.onlab.onos.net.resource.LinkResourceService;
+import org.onlab.onos.net.resource.ResourceAllocation;
+import org.onlab.onos.net.resource.ResourceRequest;
+import org.onlab.onos.net.resource.ResourceType;
+import org.onlab.onos.net.topology.DefaultTopologyEdge;
+import org.onlab.onos.net.topology.DefaultTopologyVertex;
 import org.onlab.onos.net.topology.LinkWeight;
 import org.onlab.onos.net.topology.PathService;
+import org.onlab.onos.net.topology.TopologyVertex;
 
 /**
  * Common mocks used by the intent framework tests.
@@ -101,7 +117,158 @@
 
         @Override
         public Set<Path> getPaths(ElementId src, ElementId dst, LinkWeight weight) {
-            return getPaths(src, dst);
+            final Set<Path> paths = getPaths(src, dst);
+
+            for (Path path : paths) {
+                final DeviceId srcDevice = path.src().deviceId();
+                final DeviceId dstDevice = path.dst().deviceId();
+                final TopologyVertex srcVertex = new DefaultTopologyVertex(srcDevice);
+                final TopologyVertex dstVertex = new DefaultTopologyVertex(dstDevice);
+                final Link link = link(src.toString(), 1, dst.toString(), 1);
+
+                final double weightValue = weight.weight(new DefaultTopologyEdge(srcVertex, dstVertex, link));
+                if (weightValue < 0) {
+                    return new HashSet<>();
+                }
+            }
+            return paths;
         }
     }
+
+    public static class MockLinkResourceAllocations implements LinkResourceAllocations {
+        @Override
+        public Set<ResourceAllocation> getResourceAllocation(Link link) {
+            return null;
+        }
+
+        @Override
+        public IntentId intendId() {
+            return null;
+        }
+
+        @Override
+        public Collection<Link> links() {
+            return null;
+        }
+
+        @Override
+        public Set<ResourceRequest> resources() {
+            return null;
+        }
+
+        @Override
+        public ResourceType type() {
+            return null;
+        }
+    }
+
+    public static class MockedAllocationFailure extends RuntimeException { }
+
+    public static class MockResourceService implements LinkResourceService {
+
+        double availableBandwidth = -1.0;
+        int availableLambda = -1;
+
+        /**
+         * Allocates a resource service that will allow bandwidth allocations
+         * up to a limit.
+         *
+         * @param bandwidth available bandwidth limit
+         * @return resource manager for bandwidth requests
+         */
+        public static MockResourceService makeBandwidthResourceService(double bandwidth) {
+            final MockResourceService result = new MockResourceService();
+            result.availableBandwidth = bandwidth;
+            return result;
+        }
+
+        /**
+         * Allocates a resource service that will allow lambda allocations.
+         *
+         * @param lambda Lambda to return for allocation requests. Currently unused
+         * @return resource manager for lambda requests
+         */
+        public static MockResourceService makeLambdaResourceService(int lambda) {
+            final MockResourceService result = new MockResourceService();
+            result.availableLambda = lambda;
+            return result;
+        }
+
+        public void setAvailableBandwidth(double availableBandwidth) {
+            this.availableBandwidth = availableBandwidth;
+        }
+
+        public void setAvailableLambda(int availableLambda) {
+            this.availableLambda = availableLambda;
+        }
+
+
+        @Override
+        public LinkResourceAllocations requestResources(LinkResourceRequest req) {
+            int lambda = -1;
+            double bandwidth = -1.0;
+
+            for (ResourceRequest resourceRequest : req.resources()) {
+                if (resourceRequest.type() == ResourceType.BANDWIDTH) {
+                    final BandwidthResourceRequest brr = (BandwidthResourceRequest) resourceRequest;
+                    bandwidth = brr.bandwidth().toDouble();
+                } else if (resourceRequest.type() == ResourceType.LAMBDA) {
+                    lambda = 1;
+                }
+            }
+
+            if (availableBandwidth < bandwidth) {
+                throw new MockedAllocationFailure();
+            }
+            if (lambda > 0 && availableLambda == 0) {
+                throw new MockedAllocationFailure();
+            }
+
+            return new IntentTestsMocks.MockLinkResourceAllocations();
+        }
+
+        @Override
+        public void releaseResources(LinkResourceAllocations allocations) {
+            // Mock
+        }
+
+        @Override
+        public LinkResourceAllocations updateResources(LinkResourceRequest req,
+                                                       LinkResourceAllocations oldAllocations) {
+            return null;
+        }
+
+        @Override
+        public Iterable<LinkResourceAllocations> getAllocations() {
+            return null;
+        }
+
+        @Override
+        public Iterable<LinkResourceAllocations> getAllocations(Link link) {
+            return null;
+        }
+
+        @Override
+        public LinkResourceAllocations getAllocations(IntentId intentId) {
+            return null;
+        }
+
+        @Override
+        public Iterable<ResourceRequest> getAvailableResources(Link link) {
+            final List<ResourceRequest> result = new LinkedList<>();
+            if (availableBandwidth > 0.0) {
+                result.add(new BandwidthResourceRequest(availableBandwidth));
+            }
+            if (availableLambda > 0) {
+                result.add(new LambdaResourceRequest());
+            }
+            return result;
+        }
+
+        @Override
+        public ResourceRequest getAvailableResources(Link link, LinkResourceAllocations allocations) {
+            return null;
+        }
+    }
+
 }
diff --git a/core/net/src/test/java/org/onlab/onos/net/intent/impl/PathConstraintCalculationTest.java b/core/net/src/test/java/org/onlab/onos/net/intent/impl/PathConstraintCalculationTest.java
new file mode 100644
index 0000000..3e8e7c1
--- /dev/null
+++ b/core/net/src/test/java/org/onlab/onos/net/intent/impl/PathConstraintCalculationTest.java
@@ -0,0 +1,277 @@
+/*
+ * Copyright 2014 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onlab.onos.net.intent.impl;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import org.junit.Test;
+import org.onlab.onos.net.flow.FlowRuleBatchOperation;
+import org.onlab.onos.net.flow.TrafficSelector;
+import org.onlab.onos.net.flow.TrafficTreatment;
+import org.onlab.onos.net.intent.Constraint;
+import org.onlab.onos.net.intent.Intent;
+import org.onlab.onos.net.intent.IntentTestsMocks;
+import org.onlab.onos.net.intent.PathIntent;
+import org.onlab.onos.net.intent.PointToPointIntent;
+import org.onlab.onos.net.intent.constraint.BandwidthConstraint;
+import org.onlab.onos.net.intent.constraint.LambdaConstraint;
+import org.onlab.onos.net.resource.Bandwidth;
+import org.onlab.onos.net.resource.Lambda;
+import org.onlab.onos.net.resource.LinkResourceService;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.hasSize;
+import static org.hamcrest.Matchers.instanceOf;
+import static org.hamcrest.Matchers.notNullValue;
+import static org.junit.Assert.fail;
+import static org.onlab.onos.net.NetTestTools.APP_ID;
+import static org.onlab.onos.net.NetTestTools.connectPoint;
+
+/**
+ * Unit tests for calculating paths for intents with constraints.
+ */
+
+public class PathConstraintCalculationTest {
+
+    /**
+     * Creates a point to point intent compiler for a three switch linear
+     * topology.
+     *
+     * @param resourceService service to use for resource allocation requests
+     * @return point to point compiler
+     */
+    private PointToPointIntentCompiler makeCompiler(LinkResourceService resourceService) {
+        final String[] hops = {"s1", "s2", "s3"};
+        final PointToPointIntentCompiler compiler = new PointToPointIntentCompiler();
+        compiler.resourceService = resourceService;
+        compiler.pathService = new IntentTestsMocks.MockPathService(hops);
+        return compiler;
+    }
+
+    /**
+     * Creates an intent with a given constraint and compiles it. The compiler
+     * will throw PathNotFoundException if the allocations cannot be satisfied.
+     *
+     * @param constraint constraint to apply to the created intent
+     * @param resourceService service to use for resource allocation requests
+     * @return List of compiled intents
+     */
+    private List<Intent> compileIntent(Constraint constraint,
+                                       LinkResourceService resourceService) {
+        final List<Constraint> constraints = new LinkedList<>();
+        constraints.add(constraint);
+        final TrafficSelector selector = new IntentTestsMocks.MockSelector();
+        final TrafficTreatment treatment = new IntentTestsMocks.MockTreatment();
+
+        final PointToPointIntent intent =
+                new PointToPointIntent(APP_ID,
+                                       selector,
+                                       treatment,
+                                       connectPoint("s1", 1),
+                                       connectPoint("s3", 1),
+                                       constraints);
+        final PointToPointIntentCompiler compiler = makeCompiler(resourceService);
+
+        return compiler.compile(intent);
+    }
+
+    /**
+     * Installs a compiled path intent and returns the flow rules it generates.
+     *
+     * @param compiledIntents list of compiled intents
+     * @param resourceService service to use for resource allocation requests
+     * @return
+     */
+    private List<FlowRuleBatchOperation> installIntents(List<Intent> compiledIntents,
+                                                        LinkResourceService resourceService) {
+        final PathIntent path = (PathIntent) compiledIntents.get(0);
+
+        final PathIntentInstaller installer = new PathIntentInstaller();
+        installer.resourceService = resourceService;
+        installer.appId = APP_ID;
+        return installer.install(path);
+    }
+
+    /**
+     * Tests that requests with sufficient available bandwidth succeed.
+     */
+    @Test
+    public void testBandwidthConstrainedIntentSuccess() {
+
+        final LinkResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeBandwidthResourceService(1000.0);
+        final Constraint constraint = new BandwidthConstraint(Bandwidth.valueOf(100.0));
+
+        final List<Intent> compiledIntents = compileIntent(constraint, resourceService);
+        assertThat(compiledIntents, notNullValue());
+        assertThat(compiledIntents, hasSize(1));
+    }
+
+    /**
+     * Tests that requests with insufficient available bandwidth fail.
+     */
+    @Test
+    public void testBandwidthConstrainedIntentFailure() {
+
+        final LinkResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeBandwidthResourceService(10.0);
+        final Constraint constraint = new BandwidthConstraint(Bandwidth.valueOf(100.0));
+
+        try {
+            compileIntent(constraint, resourceService);
+            fail("Point to Point compilation with insufficient bandwidth does "
+                    + "not throw exception.");
+        } catch (PathNotFoundException noPath) {
+            assertThat(noPath.getMessage(), containsString("No packet path"));
+        }
+    }
+
+    /**
+     * Tests that requests for available lambdas are successful.
+     */
+    @Test
+    public void testLambdaConstrainedIntentSuccess() {
+
+        final Constraint constraint = new LambdaConstraint(Lambda.valueOf(1));
+        final LinkResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeLambdaResourceService(1);
+
+        final List<Intent> compiledIntents =
+                compileIntent(constraint, resourceService);
+        assertThat(compiledIntents, notNullValue());
+        assertThat(compiledIntents, hasSize(1));
+    }
+
+    /**
+     * Tests that requests for lambdas when there are no available lambdas
+     * fail.
+     */
+    @Test
+    public void testLambdaConstrainedIntentFailure() {
+
+        final Constraint constraint = new LambdaConstraint(Lambda.valueOf(1));
+        final LinkResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeBandwidthResourceService(10.0);
+        try {
+            compileIntent(constraint, resourceService);
+            fail("Point to Point compilation with no available lambda does "
+                    + "not throw exception.");
+        } catch (PathNotFoundException noPath) {
+            assertThat(noPath.getMessage(), containsString("No packet path"));
+        }
+    }
+
+    /**
+     * Tests that installation of bandwidth constrained path intents are
+     * successful.
+     */
+    @Test
+    public void testInstallBandwidthConstrainedIntentSuccess() {
+
+        final IntentTestsMocks.MockResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeBandwidthResourceService(1000.0);
+        final Constraint constraint = new BandwidthConstraint(Bandwidth.valueOf(100.0));
+
+        final List<Intent> compiledIntents = compileIntent(constraint, resourceService);
+        assertThat(compiledIntents, notNullValue());
+        assertThat(compiledIntents, hasSize(1));
+
+        final List<FlowRuleBatchOperation> flowOperations =
+                installIntents(compiledIntents, resourceService);
+
+        assertThat(flowOperations, notNullValue());
+        assertThat(flowOperations, hasSize(1));
+    }
+
+    /**
+     * Tests that installation of bandwidth constrained path intents fail
+     * if there are no available resources.
+     */
+    @Test
+    public void testInstallBandwidthConstrainedIntentFailure() {
+
+        final IntentTestsMocks.MockResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeBandwidthResourceService(1000.0);
+        final Constraint constraint = new BandwidthConstraint(Bandwidth.valueOf(100.0));
+
+        final List<Intent> compiledIntents = compileIntent(constraint, resourceService);
+        assertThat(compiledIntents, notNullValue());
+        assertThat(compiledIntents, hasSize(1));
+
+        // Make it look like the available bandwidth was consumed
+        resourceService.setAvailableBandwidth(1.0);
+
+        try {
+            installIntents(compiledIntents, resourceService);
+            fail("Bandwidth request with no available bandwidth did not fail.");
+        } catch (IntentTestsMocks.MockedAllocationFailure failure) {
+            assertThat(failure,
+                       instanceOf(IntentTestsMocks.MockedAllocationFailure.class));
+        }
+    }
+
+    /**
+     * Tests that installation of lambda constrained path intents are
+     * successful.
+     */
+    @Test
+    public void testInstallLambdaConstrainedIntentSuccess() {
+
+        final IntentTestsMocks.MockResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeLambdaResourceService(1);
+        final Constraint constraint = new LambdaConstraint(Lambda.valueOf(1));
+
+        final List<Intent> compiledIntents = compileIntent(constraint, resourceService);
+        assertThat(compiledIntents, notNullValue());
+        assertThat(compiledIntents, hasSize(1));
+
+        final List<FlowRuleBatchOperation> flowOperations =
+                installIntents(compiledIntents, resourceService);
+
+        assertThat(flowOperations, notNullValue());
+        assertThat(flowOperations, hasSize(1));
+    }
+
+    /**
+     * Tests that installation of lambda constrained path intents fail
+     * if there are no available resources.
+     */
+    @Test
+    public void testInstallLambdaConstrainedIntentFailure() {
+
+        final IntentTestsMocks.MockResourceService resourceService =
+                IntentTestsMocks.MockResourceService.makeLambdaResourceService(1);
+        final Constraint constraint = new LambdaConstraint(Lambda.valueOf(1));
+
+        final List<Intent> compiledIntents = compileIntent(constraint, resourceService);
+        assertThat(compiledIntents, notNullValue());
+        assertThat(compiledIntents, hasSize(1));
+
+        // Make it look like the available lambda was consumed
+        resourceService.setAvailableLambda(0);
+
+        try {
+            installIntents(compiledIntents, resourceService);
+            fail("Lambda request with no available lambda did not fail.");
+        } catch (IntentTestsMocks.MockedAllocationFailure failure) {
+            assertThat(failure,
+                       instanceOf(IntentTestsMocks.MockedAllocationFailure.class));
+        }
+    }
+
+}
diff --git a/web/gui/src/main/webapp/index2.html b/web/gui/src/main/webapp/index2.html
index 66050c6..03272e9 100644
--- a/web/gui/src/main/webapp/index2.html
+++ b/web/gui/src/main/webapp/index2.html
@@ -44,6 +44,7 @@
     <!-- This is where contributed stylesheets get INJECTED -->
     <!-- TODO: replace with template marker and inject refs server-side -->
     <link rel="stylesheet" href="topo2.css">
+    <link rel="stylesheet" href="webSockTrace.css">
 
 
     <!-- General library modules included here-->
@@ -97,6 +98,7 @@
 
     <!-- Contributed (application) views injected here -->
     <!-- TODO: replace with template marker and inject refs server-side -->
+    <script src="webSockTrace.js"></script>
     <script src="topo2.js"></script>
 
     <!-- finally, build the UI-->
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/addDevice_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/rx/addDevice_ex1.json
new file mode 100644
index 0000000..f00cf2c
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/addDevice_ex1.json
@@ -0,0 +1,15 @@
+{
+  "event": "addDevice",
+  "payload": {
+    "id": "of:0000000000000003",
+    "type": "switch",
+    "online": true,
+    "labels": [
+      "of:0000000000000003",
+      "3",
+      "",
+      null
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/addHost_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/rx/addHost_ex1.json
new file mode 100644
index 0000000..a97d15a
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/addHost_ex1.json
@@ -0,0 +1,17 @@
+{
+  "event": "addHost",
+  "payload": {
+    "id": "6A:40:24:F7:9C:2C/-1",
+    "ingress": "6A:40:24:F7:9C:2C/-1/0-of:0000000000000003/2",
+    "egress": "of:0000000000000003/2-6A:40:24:F7:9C:2C/-1/0",
+    "cp": {
+      "device": "of:0000000000000003",
+      "port": 2
+    },
+    "labels": [
+      "unknown",
+      "6A:40:24:F7:9C:2C"
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/addLink_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/rx/addLink_ex1.json
new file mode 100644
index 0000000..92c7848
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/addLink_ex1.json
@@ -0,0 +1,12 @@
+{
+  "event": "addLink",
+  "payload": {
+    "id": "of:0000000000000007/4-of:0000000000000006/1",
+    "type": "direct",
+    "linkWidth": 2,
+    "src": "of:0000000000000007",
+    "srcPort": "4",
+    "dst": "of:0000000000000006",
+    "dstPort": "1"
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/removeDevice_fab.json b/web/gui/src/main/webapp/json/ev/_capture/rx/removeDevice_fab.json
new file mode 100644
index 0000000..0e8d47a
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/removeDevice_fab.json
@@ -0,0 +1,20 @@
+{
+  "__comments__": [
+    "fabricated event",
+    "not sure if this is the actual format",
+    "but we really only care about 'id' being in the payload"
+  ],
+  "event": "removeDevice",
+  "payload": {
+    "id": "of:0000000000000002",
+    "type": "switch",
+    "online": true,
+    "labels": [
+      "of:0000000000000002",
+      "2",
+      "",
+      null
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/removeHost_fab.json b/web/gui/src/main/webapp/json/ev/_capture/rx/removeHost_fab.json
new file mode 100644
index 0000000..4237199
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/removeHost_fab.json
@@ -0,0 +1,22 @@
+{
+  "__comments__": [
+    "fabricated event",
+    "not sure if this is the actual format",
+    "but we really only care about 'id' being in the payload"
+  ],
+  "event": "removeHost",
+  "payload": {
+    "id": "6A:40:24:F7:9C:2C/-1",
+    "ingress": "6A:40:24:F7:9C:2C/-1/0-of:0000000000000003/2",
+    "egress": "of:0000000000000003/2-6A:40:24:F7:9C:2C/-1/0",
+    "cp": {
+      "device": "of:0000000000000003",
+      "port": 2
+    },
+    "labels": [
+      "unknown",
+      "6A:40:24:F7:9C:2C"
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/removeLink_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/rx/removeLink_ex1.json
new file mode 100644
index 0000000..8d1dd03
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/removeLink_ex1.json
@@ -0,0 +1,12 @@
+{
+  "event": "removeLink",
+  "payload": {
+    "id": "of:0000000000000001/1-of:0000000000000002/4",
+    "type": "direct",
+    "linkWidth": 2,
+    "src": "of:0000000000000001",
+    "srcPort": "1",
+    "dst": "of:0000000000000002",
+    "dstPort": "4"
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/showPath_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/rx/showPath_ex1.json
new file mode 100644
index 0000000..de1023e
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/showPath_ex1.json
@@ -0,0 +1,15 @@
+{
+  "event": "showPath",
+  "sid": 15,
+  "payload": {
+    "links": [
+      "62:4F:65:BF:FF:B3/-1/0-of:000000000000000b/1",
+      "of:000000000000000b/4-of:000000000000000a/1",
+      "of:000000000000000a/4-of:0000000000000001/3",
+      "of:0000000000000001/1-of:0000000000000002/4",
+      "of:0000000000000002/1-of:0000000000000003/4",
+      "of:0000000000000003/1-CA:4B:EE:A4:B0:33/-1/0"
+    ],
+    "intentId": "0x52a914f9"
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/updateDevice_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/rx/updateDevice_ex1.json
new file mode 100644
index 0000000..dda6186
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/updateDevice_ex1.json
@@ -0,0 +1,15 @@
+{
+  "event": "updateDevice",
+  "payload": {
+    "id": "of:0000000000000002",
+    "type": "switch",
+    "online": true,
+    "labels": [
+      "of:0000000000000002",
+      "2",
+      "",
+      null
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/updateDevice_ex2.json b/web/gui/src/main/webapp/json/ev/_capture/rx/updateDevice_ex2.json
new file mode 100644
index 0000000..d607f98
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/updateDevice_ex2.json
@@ -0,0 +1,15 @@
+{
+  "event": "updateDevice",
+  "payload": {
+    "id": "of:0000000000000002",
+    "type": "switch",
+    "online": false,
+    "labels": [
+      "of:0000000000000002",
+      "2",
+      "",
+      null
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/updateHost.json b/web/gui/src/main/webapp/json/ev/_capture/rx/updateHost.json
new file mode 100644
index 0000000..fd7361c
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/updateHost.json
@@ -0,0 +1,17 @@
+{
+  "event": "updateHost",
+  "payload": {
+    "id": "AA:C2:74:3F:B8:06/-1",
+    "ingress": "AA:C2:74:3F:B8:06/-1/0-of:0000000000000005/3",
+    "egress": "of:0000000000000005/3-AA:C2:74:3F:B8:06/-1/0",
+    "cp": {
+      "device": "of:0000000000000005",
+      "port": 3
+    },
+    "labels": [
+      "10.0.0.9",
+      "AA:C2:74:3F:B8:06"
+    ],
+    "props":{}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/rx/updateLink_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/rx/updateLink_ex1.json
new file mode 100644
index 0000000..3be5c5f
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/rx/updateLink_ex1.json
@@ -0,0 +1,12 @@
+{
+  "event": "updateLink",
+  "payload": {
+    "id": "of:0000000000000002/4-of:0000000000000001/1",
+    "type": "direct",
+    "linkWidth": 2,
+    "src": "of:0000000000000002",
+    "srcPort": "4",
+    "dst": "of:0000000000000001",
+    "dstPort": "1"
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/tx/requestPath_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/tx/requestPath_ex1.json
new file mode 100644
index 0000000..4963865
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/tx/requestPath_ex1.json
@@ -0,0 +1,8 @@
+{
+  "event": "requestPath",
+  "sid": 15,
+  "payload": {
+    "one": "62:4F:65:BF:FF:B3/-1",
+    "two": "CA:4B:EE:A4:B0:33/-1"
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/_capture/tx/updateMeta_ex1.json b/web/gui/src/main/webapp/json/ev/_capture/tx/updateMeta_ex1.json
new file mode 100644
index 0000000..c04727e
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/_capture/tx/updateMeta_ex1.json
@@ -0,0 +1,10 @@
+{
+  "event": "updateMeta",
+  "sid": 11,
+  "payload": {
+    "id": "62:4F:65:BF:FF:B3/-1",
+    "class": "host",
+    "x": 197,
+    "y": 177
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/intent/ev_1_ui.json b/web/gui/src/main/webapp/json/ev/intentSketch/ev_1_ui.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/ev_1_ui.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/ev_1_ui.json
diff --git a/web/gui/src/main/webapp/json/ev/intent/ev_2_onos.json b/web/gui/src/main/webapp/json/ev/intentSketch/ev_2_onos.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/ev_2_onos.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/ev_2_onos.json
diff --git a/web/gui/src/main/webapp/json/ev/intent/ev_3_ui.json b/web/gui/src/main/webapp/json/ev/intentSketch/ev_3_ui.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/ev_3_ui.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/ev_3_ui.json
diff --git a/web/gui/src/main/webapp/json/ev/intent/ev_4_onos.json b/web/gui/src/main/webapp/json/ev/intentSketch/ev_4_onos.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/ev_4_onos.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/ev_4_onos.json
diff --git a/web/gui/src/main/webapp/json/ev/intent/ev_5_onos.json b/web/gui/src/main/webapp/json/ev/intentSketch/ev_5_onos.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/ev_5_onos.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/ev_5_onos.json
diff --git a/web/gui/src/main/webapp/json/ev/intent/ev_6_onos.json b/web/gui/src/main/webapp/json/ev/intentSketch/ev_6_onos.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/ev_6_onos.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/ev_6_onos.json
diff --git a/web/gui/src/main/webapp/json/ev/intent/ev_7_ui.json b/web/gui/src/main/webapp/json/ev/intentSketch/ev_7_ui.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/ev_7_ui.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/ev_7_ui.json
diff --git a/web/gui/src/main/webapp/json/ev/intent/scenario.json b/web/gui/src/main/webapp/json/ev/intentSketch/scenario.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/intent/scenario.json
rename to web/gui/src/main/webapp/json/ev/intentSketch/scenario.json
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_8_ui.json b/web/gui/src/main/webapp/json/ev/simple/ev_10_ui.json
similarity index 100%
rename from web/gui/src/main/webapp/json/ev/simple/ev_8_ui.json
rename to web/gui/src/main/webapp/json/ev/simple/ev_10_ui.json
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_3_onos.json b/web/gui/src/main/webapp/json/ev/simple/ev_3_onos.json
index ac521c4..73013a4 100644
--- a/web/gui/src/main/webapp/json/ev/simple/ev_3_onos.json
+++ b/web/gui/src/main/webapp/json/ev/simple/ev_3_onos.json
@@ -1,15 +1,18 @@
 {
-  "event": "addLink",
+  "event": "updateDevice",
   "payload": {
-    "id": "of:0000ffffffff0003/21-of:0000ffffffff0008/20",
-    "type": "direct",
-    "linkWidth": 2,
-    "src": "of:0000ffffffff0003",
-    "srcPort": "21",
-    "dst": "of:0000ffffffff0008",
-    "dstPort": "20",
-    "props" : {
-      "BW": "70 G"
+    "id": "of:0000ffffffff0008",
+    "type": "switch",
+    "online": true,
+    "labels": [
+      "0000ffffffff0008",
+      "FF:FF:FF:FF:00:08",
+      "sw-8-yo",
+      ""
+    ],
+    "metaUi": {
+      "x": 400,
+      "y": 280
     }
   }
 }
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_4_onos.json b/web/gui/src/main/webapp/json/ev/simple/ev_4_onos.json
index 993570b..958af28 100644
--- a/web/gui/src/main/webapp/json/ev/simple/ev_4_onos.json
+++ b/web/gui/src/main/webapp/json/ev/simple/ev_4_onos.json
@@ -1,17 +1,18 @@
 {
-  "event": "addHost",
+  "event": "updateDevice",
   "payload": {
-    "id": "0E:2A:69:30:13:86/-1",
-    "ingress": "0E:2A:69:30:13:86/-1/0-of:0000ffffffff0003/2",
-    "egress": "of:0000ffffffff0003/2-0E:2A:69:30:13:86/-1/0",
-    "cp": {
-      "device": "of:0000ffffffff0003",
-      "port": 2
-    },
+    "id": "of:0000ffffffff0003",
+    "type": "switch",
+    "online": true,
     "labels": [
-      "unknown",
-      "0E:2A:69:30:13:86"
+      "0000ffffffff0003",
+      "FF:FF:FF:FF:00:03",
+      "sw-3-yo",
+      ""
     ],
-    "props": {}
+    "metaUi": {
+      "x": 800,
+      "y": 280
+    }
   }
 }
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_5_onos.json b/web/gui/src/main/webapp/json/ev/simple/ev_5_onos.json
index 17864a6..ac521c4 100644
--- a/web/gui/src/main/webapp/json/ev/simple/ev_5_onos.json
+++ b/web/gui/src/main/webapp/json/ev/simple/ev_5_onos.json
@@ -1,17 +1,15 @@
 {
-  "event": "addHost",
+  "event": "addLink",
   "payload": {
-    "id": "A6:96:E5:03:52:5F/-1",
-    "ingress": "A6:96:E5:03:52:5F/-1/0-of:0000ffffffff0008/1",
-    "egress": "of:0000ffffffff0008/1-A6:96:E5:03:52:5F/-1/0",
-    "cp": {
-      "device": "of:0000ffffffff0008",
-      "port": 1
-    },
-    "labels": [
-      "unknown",
-      "A6:96:E5:03:52:5F"
-    ],
-    "props": {}
+    "id": "of:0000ffffffff0003/21-of:0000ffffffff0008/20",
+    "type": "direct",
+    "linkWidth": 2,
+    "src": "of:0000ffffffff0003",
+    "srcPort": "21",
+    "dst": "of:0000ffffffff0008",
+    "dstPort": "20",
+    "props" : {
+      "BW": "70 G"
+    }
   }
 }
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_6_onos.json b/web/gui/src/main/webapp/json/ev/simple/ev_6_onos.json
index 3a3ea9e..993570b 100644
--- a/web/gui/src/main/webapp/json/ev/simple/ev_6_onos.json
+++ b/web/gui/src/main/webapp/json/ev/simple/ev_6_onos.json
@@ -1,5 +1,5 @@
 {
-  "event": "updateHost",
+  "event": "addHost",
   "payload": {
     "id": "0E:2A:69:30:13:86/-1",
     "ingress": "0E:2A:69:30:13:86/-1/0-of:0000ffffffff0003/2",
@@ -9,7 +9,7 @@
       "port": 2
     },
     "labels": [
-      "10.0.0.13",
+      "unknown",
       "0E:2A:69:30:13:86"
     ],
     "props": {}
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_7_onos.json b/web/gui/src/main/webapp/json/ev/simple/ev_7_onos.json
index 0fb56fa..17864a6 100644
--- a/web/gui/src/main/webapp/json/ev/simple/ev_7_onos.json
+++ b/web/gui/src/main/webapp/json/ev/simple/ev_7_onos.json
@@ -1,5 +1,5 @@
 {
-  "event": "updateHost",
+  "event": "addHost",
   "payload": {
     "id": "A6:96:E5:03:52:5F/-1",
     "ingress": "A6:96:E5:03:52:5F/-1/0-of:0000ffffffff0008/1",
@@ -9,7 +9,7 @@
       "port": 1
     },
     "labels": [
-      "10.0.0.17",
+      "unknown",
       "A6:96:E5:03:52:5F"
     ],
     "props": {}
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_8_onos.json b/web/gui/src/main/webapp/json/ev/simple/ev_8_onos.json
new file mode 100644
index 0000000..3a3ea9e
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/simple/ev_8_onos.json
@@ -0,0 +1,17 @@
+{
+  "event": "updateHost",
+  "payload": {
+    "id": "0E:2A:69:30:13:86/-1",
+    "ingress": "0E:2A:69:30:13:86/-1/0-of:0000ffffffff0003/2",
+    "egress": "of:0000ffffffff0003/2-0E:2A:69:30:13:86/-1/0",
+    "cp": {
+      "device": "of:0000ffffffff0003",
+      "port": 2
+    },
+    "labels": [
+      "10.0.0.13",
+      "0E:2A:69:30:13:86"
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/simple/ev_9_onos.json b/web/gui/src/main/webapp/json/ev/simple/ev_9_onos.json
new file mode 100644
index 0000000..0fb56fa
--- /dev/null
+++ b/web/gui/src/main/webapp/json/ev/simple/ev_9_onos.json
@@ -0,0 +1,17 @@
+{
+  "event": "updateHost",
+  "payload": {
+    "id": "A6:96:E5:03:52:5F/-1",
+    "ingress": "A6:96:E5:03:52:5F/-1/0-of:0000ffffffff0008/1",
+    "egress": "of:0000ffffffff0008/1-A6:96:E5:03:52:5F/-1/0",
+    "cp": {
+      "device": "of:0000ffffffff0008",
+      "port": 1
+    },
+    "labels": [
+      "10.0.0.17",
+      "A6:96:E5:03:52:5F"
+    ],
+    "props": {}
+  }
+}
diff --git a/web/gui/src/main/webapp/json/ev/simple/scenario.json b/web/gui/src/main/webapp/json/ev/simple/scenario.json
index e320413..19d6190 100644
--- a/web/gui/src/main/webapp/json/ev/simple/scenario.json
+++ b/web/gui/src/main/webapp/json/ev/simple/scenario.json
@@ -6,5 +6,17 @@
   "title": "Simple Startup Scenario",
   "params": {
     "lastAuto": 0
-  }
+  },
+  "description": [
+    "1. add device [8] (offline)",
+    "2. add device [3] (offline)",
+    "3. update device [8] (online)",
+    "4. update device [3] (online)",
+    "5. add link [3] --> [8]",
+    "6. add host (to [3])",
+    "7. add host (to [8])",
+    "8. update host[3] (IP now 10.0.0.13)",
+    "9. update host[8] (IP now 10.0.0.17)",
+    ""
+  ]
 }
\ No newline at end of file
diff --git a/web/gui/src/main/webapp/onos2.js b/web/gui/src/main/webapp/onos2.js
index a31b20f..f38b35f 100644
--- a/web/gui/src/main/webapp/onos2.js
+++ b/web/gui/src/main/webapp/onos2.js
@@ -33,7 +33,8 @@
         var uiApi,
             viewApi,
             navApi,
-            libApi;
+            libApi,
+            exported = {};
 
         var defaultOptions = {
             trace: false,
@@ -658,6 +659,7 @@
                 return makeUid(this, id);
             },
 
+            // TODO : add exportApi and importApi methods
             // TODO : implement custom dialogs
 
             // Consider enhancing alert mechanism to handle multiples
@@ -737,6 +739,7 @@
         // ..........................................................
         // View API
 
+        // TODO: deprecated
         viewApi = {
             /** @api view empty( )
              * Empties the current view.
@@ -802,7 +805,8 @@
             lib: libApi,
             //view: viewApi,
             nav: navApi,
-            buildUi: buildOnosUi
+            buildUi: buildOnosUi,
+            exported: exported
         };
     };
 
diff --git a/web/gui/src/main/webapp/topo2.css b/web/gui/src/main/webapp/topo2.css
index acd0bc9..6c0c313 100644
--- a/web/gui/src/main/webapp/topo2.css
+++ b/web/gui/src/main/webapp/topo2.css
@@ -41,11 +41,16 @@
     stroke: #ccc;
 }
 
-#topo svg .node.device.switch {
+/* note: device is offline without the 'online' class */
+#topo svg .node.device {
+    fill: #777;
+}
+
+#topo svg .node.device.switch.online {
     fill: #17f;
 }
 
-#topo svg .node.device.roadm {
+#topo svg .node.device.roadm.online {
     fill: #03c;
 }
 
@@ -53,12 +58,17 @@
     fill: #846;
 }
 
+/* note: device is offline without the 'online' class */
 #topo svg .node.device text {
-    fill: white;
+    fill: #aaa;
     font: 10pt sans-serif;
     pointer-events: none;
 }
 
+#topo svg .node.device.online text {
+    fill: white;
+}
+
 #topo svg .node.host text {
     fill: #846;
     font: 9pt sans-serif;
diff --git a/web/gui/src/main/webapp/topo2.js b/web/gui/src/main/webapp/topo2.js
index 55e463c..f6a8456 100644
--- a/web/gui/src/main/webapp/topo2.js
+++ b/web/gui/src/main/webapp/topo2.js
@@ -24,7 +24,8 @@
     'use strict';
 
     // shorter names for library APIs
-    var d3u = onos.lib.d3util;
+    var d3u = onos.lib.d3util,
+        trace;
 
     // configuration data
     var config = {
@@ -241,8 +242,8 @@
     }
 
     function handleUiEvent(data) {
-        testDebug('handleUiEvent(): ' + data.event);
-        // TODO:
+        scenario.view.alert('UI Tx: ' + data.event + '\n\n' +
+            JSON.stringify(data));
     }
 
     function injectStartupEvents(view) {
@@ -259,32 +260,44 @@
         bgImg.style('visibility', (vis === 'hidden') ? 'visible' : 'hidden');
     }
 
+    function updateDeviceLabel(d) {
+        var label = niceLabel(deviceLabel(d)),
+            node = d.el,
+            box;
+
+        node.select('text')
+            .text(label)
+            .style('opacity', 0)
+            .transition()
+            .style('opacity', 1);
+
+        box = adjustRectToFitText(node);
+
+        node.select('rect')
+            .transition()
+            .attr(box);
+
+        node.select('image')
+            .transition()
+            .attr('x', box.x + config.icons.xoff)
+            .attr('y', box.y + config.icons.yoff);
+    }
+
+    function updateHostLabel(d) {
+        var label = hostLabel(d),
+            host = d.el;
+
+        host.select('text').text(label);
+    }
+
     function cycleLabels() {
-        deviceLabelIndex = (deviceLabelIndex === network.deviceLabelCount - 1) ? 0 : deviceLabelIndex + 1;
+        deviceLabelIndex = (deviceLabelIndex === network.deviceLabelCount - 1)
+            ? 0 : deviceLabelIndex + 1;
 
         network.nodes.forEach(function (d) {
-            if (d.class !== 'device') { return; }
-
-            var label = niceLabel(deviceLabel(d)),
-                node = d.el,
-                box;
-
-            node.select('text')
-                .text(label)
-                .style('opacity', 0)
-                .transition()
-                .style('opacity', 1);
-
-            box = adjustRectToFitText(node);
-
-            node.select('rect')
-                .transition()
-                .attr(box);
-
-            node.select('image')
-                .transition()
-                .attr('x', box.x + config.icons.xoff)
-                .attr('y', box.y + config.icons.yoff);
+            if (d.class === 'device') {
+                updateDeviceLabel(d);
+            }
         });
     }
 
@@ -348,15 +361,20 @@
     // ==============================
     // Event handlers for server-pushed events
 
+    function logicError(msg) {
+        // TODO, report logic error to server, via websock, so it can be logged
+        network.view.alert('Logic Error:\n\n' + msg);
+    }
+
     var eventDispatch = {
         addDevice: addDevice,
-        updateDevice: stillToImplement,
-        removeDevice: stillToImplement,
         addLink: addLink,
-        updateLink: stillToImplement,
-        removeLink: stillToImplement,
         addHost: addHost,
+        updateDevice: updateDevice,
+        updateLink: stillToImplement,
         updateHost: updateHost,
+        removeDevice: stillToImplement,
+        removeLink: stillToImplement,
         removeHost: stillToImplement,
         showPath: showPath
     };
@@ -364,8 +382,6 @@
     function addDevice(data) {
         var device = data.payload,
             nodeData = createDeviceNode(device);
-        note('addDevice', device.id);
-
         network.nodes.push(nodeData);
         network.lookup[nodeData.id] = nodeData;
         updateNodes();
@@ -375,10 +391,7 @@
     function addLink(data) {
         var link = data.payload,
             lnk = createLink(link);
-
         if (lnk) {
-            note('addLink', link.id);
-
             network.links.push(lnk);
             network.lookup[lnk.id] = lnk;
             updateLinks();
@@ -390,8 +403,6 @@
         var host = data.payload,
             node = createHostNode(host),
             lnk;
-        note('addHost', node.id);
-
         network.nodes.push(node);
         network.lookup[host.id] = node;
         updateNodes();
@@ -406,13 +417,28 @@
         network.force.start();
     }
 
+    function updateDevice(data) {
+        var device = data.payload,
+            id = device.id,
+            nodeData = network.lookup[id];
+        if (nodeData) {
+            $.extend(nodeData, device);
+            updateDeviceState(nodeData);
+        } else {
+            logicError('updateDevice lookup fail. ID = "' + id + '"');
+        }
+    }
+
     function updateHost(data) {
         var host = data.payload,
-            hostData = network.lookup[host.id];
-        note('updateHost', host.id);
-
-        $.extend(hostData, host);
-        updateNodes();
+            id = host.id,
+            hostData = network.lookup[id];
+        if (hostData) {
+            $.extend(hostData, host);
+            updateHostState(hostData);
+        } else {
+            logicError('updateHost lookup fail. ID = "' + id + '"');
+        }
     }
 
     function showPath(data) {
@@ -466,9 +492,8 @@
             lnk;
 
         if (!dstNode) {
-            // TODO: send warning message back to server on websocket
-            network.view.alert('switch not on map for link\n\n' +
-            'src = ' + src + '\ndst = ' + dst);
+            logicError('switch not on map for link\n\n' +
+                        'src = ' + src + '\ndst = ' + dst);
             return null;
         }
 
@@ -500,9 +525,8 @@
             dstNode = network.lookup[dst];
 
         if (!(srcNode && dstNode)) {
-            // TODO: send warning message back to server on websocket
-            network.view.alert('nodes not on map for link\n\n' +
-                'src = ' + src + '\ndst = ' + dst);
+            logicError('nodes not on map for link\n\n' +
+            'src = ' + src + '\ndst = ' + dst);
             return null;
         }
 
@@ -578,11 +602,12 @@
     function createDeviceNode(device) {
         // start with the object as is
         var node = device,
-            type = device.type;
+            type = device.type,
+            svgCls = type ? 'node device ' + type : 'node device';
 
         // Augment as needed...
         node.class = 'device';
-        node.svgClass = type ? 'node device ' + type : 'node device';
+        node.svgClass = device.online ? svgCls + ' online' : svgCls;
         positionNode(node);
 
         // cache label array length
@@ -669,15 +694,24 @@
         return (label && label.trim()) ? label : '.';
     }
 
+    function updateDeviceState(nodeData) {
+        nodeData.el.classed('online', nodeData.online);
+        updateDeviceLabel(nodeData);
+        // TODO: review what else might need to be updated
+    }
+
+    function updateHostState(hostData) {
+        updateHostLabel(hostData);
+        // TODO: review what else might need to be updated
+    }
+
+
     function updateNodes() {
         node = nodeG.selectAll('.node')
             .data(network.nodes, function (d) { return d.id; });
 
         // operate on existing nodes, if necessary
         //  update host labels
-        node.filter('.host').select('text')
-            .text(hostLabel);
-
         //node .foo() .bar() ...
 
         // operate on entering nodes:
@@ -828,7 +862,7 @@
 
             webSock.ws.onmessage = function(m) {
                 if (m.data) {
-                    console.log(m.data);
+                    wsTraceRx(m.data);
                     handleServerEvent(JSON.parse(m.data));
                 }
             };
@@ -858,11 +892,28 @@
 
     function sendMessage(evType, payload) {
         var toSend = {
-            event: evType,
-            sid: ++sid,
-            payload: payload
-        };
-        webSock.send(JSON.stringify(toSend));
+                event: evType,
+                sid: ++sid,
+                payload: payload
+            },
+            asText = JSON.stringify(toSend);
+        wsTraceTx(asText);
+        webSock.send(asText);
+    }
+
+    function wsTraceTx(msg) {
+        wsTrace('tx', msg);
+    }
+    function wsTraceRx(msg) {
+        wsTrace('rx', msg);
+    }
+    function wsTrace(rxtx, msg) {
+
+        console.log('[' + rxtx + '] ' + msg);
+        // TODO: integrate with trace view
+        //if (trace) {
+        //    trace.output(rxtx, msg);
+        //}
     }
 
 
@@ -944,12 +995,19 @@
         sc.evNumber = 0;
 
         d3.json(urlSc, function(err, data) {
-            var p = data && data.params || {};
+            var p = data && data.params || {},
+                desc = data && data.description || null,
+                intro;
+
             if (err) {
                 view.alert('No scenario found:\n\n' + urlSc + '\n\n' + err);
             } else {
                 sc.params = p;
-                view.alert("Scenario loaded: " + ctx + '\n\n' + data.title);
+                intro = "Scenario loaded: " + ctx + '\n\n' + data.title;
+                if (desc) {
+                    intro += '\n\n  ' + desc.join('\n  ');
+                }
+                view.alert(intro);
             }
         });
 
@@ -967,6 +1025,9 @@
             fpad = fcfg.pad,
             forceDim = [w - 2*fpad, h - 2*fpad];
 
+        // TODO: set trace api
+        //trace = onos.exported.webSockTrace;
+
         // NOTE: view.$div is a D3 selection of the view's div
         svg = view.$div.append('svg');
         setSize(svg, view);
diff --git a/web/gui/src/main/webapp/webSockTrace.css b/web/gui/src/main/webapp/webSockTrace.css
new file mode 100644
index 0000000..6669124
--- /dev/null
+++ b/web/gui/src/main/webapp/webSockTrace.css
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2014 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ ONOS GUI -- Web Socket Trace -- CSS file
+
+ @author Simon Hunt
+ */
+
+#webSockTrace .toolbar {
+    height: 36px;
+    padding: 4px;
+    vertical-align: baseline;
+    font-size: 12pt;
+    margin-top: 6px;
+}
+
+/* theme-related */
+#webSockTrace .toolbar {
+    background-color: #448;
+    color: #fff;
+}
+
+#webSockTrace .output {
+    overflow-y: scroll;
+}
+
+/* theme-related */
+#webSockTrace .output {
+    background-color: #eef;
+    color: #226;
+}
+
+#webSockTrace .output p {
+    margin: 2px 8px;
+    font-size: 10pt;
+    padding-left: 6px;
+}
+
+/* theme-related */
+#webSockTrace .output p.tx {
+    color: magenta;
+}
+#webSockTrace .output p.rx {
+    color: blue;
+}
+
+
+#webSockTrace .output p.subtitle {
+    margin: 6px 8px;
+    padding-left: 2px;
+    font-size: 12pt;
+    font-weight: bold;
+    font-style: italic;
+}
+
+/* theme-related */
+#webSockTrace .output p.subtitle {
+    color: #626;
+}
diff --git a/web/gui/src/main/webapp/webSockTrace.js b/web/gui/src/main/webapp/webSockTrace.js
new file mode 100644
index 0000000..2f09b31
--- /dev/null
+++ b/web/gui/src/main/webapp/webSockTrace.js
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2014 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ View that traces messages across the websocket.
+
+ @author Simon Hunt
+ */
+
+(function (onos) {
+    'use strict';
+
+    var v,
+        $d,
+        tb,
+        out,
+        which = 'tx',
+        keyDispatch = {
+            space: function () {
+                output(which, "Simon woz 'ere... " + which);
+                which = (which === 'tx') ? 'rx' : 'tx';
+            }
+        };
+
+
+    function addHeader() {
+        tb = $d.append('div')
+            .attr('class', 'toolbar');
+        tb.append('span').text('Web Socket Trace');
+    }
+
+    function addOutput() {
+        out = $d.append('div')
+            .attr('class', 'output');
+    }
+
+    function subtitle(msg) {
+        out.append('p').attr('class', 'subtitle').text(msg);
+    }
+
+    function output(rxtx, msg) {
+        out.append('p').attr('class', rxtx).text(msg);
+    }
+
+    // invoked only the first time the view is loaded
+    function preload(view, ctx, flags) {
+        // NOTE: view.$div is a D3 selection of the view's div
+        v = view;
+        $d = v.$div;
+        addHeader();
+        addOutput();
+
+
+        // hack for now, to allow topo access to our API
+        // TODO: add 'exportApi' and 'importApi' to views.
+        onos.exported.webSockTrace = {
+            subtitle: subtitle,
+            output: output
+        };
+    }
+
+    // invoked just prior to loading the view
+    function reset(view, ctx, flags) {
+
+    }
+
+    // invoked when the view is loaded
+    function load(view, ctx, flags) {
+        resize(view, ctx, flags);
+        view.setKeys(keyDispatch);
+        subtitle('Waiting for messages...');
+    }
+
+    // invoked when the view is resized
+    function resize(view, ctx, flags) {
+        var h = view.height();
+        out.style('height', h + 'px');
+
+    }
+
+    // == register the view here, with links to lifecycle callbacks
+
+    onos.ui.addView('webSockTrace', {
+        preload: preload,
+        load: load,
+        resize: resize
+    });
+
+}(ONOS));