Initial sketch of codecs and REST API approach.
FIxed typos and defects.
ONOS-81

Change-Id: I789444a181abea509c354966545c927e305710d1
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/AnnotatedCodec.java b/web/api/src/main/java/org/onlab/onos/codec/impl/AnnotatedCodec.java
new file mode 100644
index 0000000..1a6c511
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/AnnotatedCodec.java
@@ -0,0 +1,45 @@
+/*
+ * 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.codec.impl;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.onos.codec.CodecContext;
+import org.onlab.onos.codec.JsonCodec;
+import org.onlab.onos.net.Annotated;
+import org.onlab.onos.net.Annotations;
+
+/**
+ * Base JSON codec for annotated entities.
+ */
+public abstract class AnnotatedCodec<T extends Annotated> extends JsonCodec<T> {
+
+    /**
+     * Adds JSON encoding of the given item annotations to the specified node.
+     *
+     * @param node    node to add annotations to
+     * @param entity  annotated entity
+     * @param context encode context
+     * @return the given node
+     */
+    protected ObjectNode annotate(ObjectNode node, T entity, CodecContext context) {
+        if (!entity.annotations().keys().isEmpty()) {
+            JsonCodec<Annotations> codec = context.codec(Annotations.class);
+            node.set("annotations", codec.encode(entity.annotations(), context));
+        }
+        return node;
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/AnnotationsCodec.java b/web/api/src/main/java/org/onlab/onos/codec/impl/AnnotationsCodec.java
new file mode 100644
index 0000000..a8d2907
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/AnnotationsCodec.java
@@ -0,0 +1,37 @@
+/*
+ * 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.codec.impl;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.onos.codec.CodecContext;
+import org.onlab.onos.codec.JsonCodec;
+import org.onlab.onos.net.Annotations;
+
+/**
+ * Annotations JSON codec.
+ */
+public class AnnotationsCodec extends JsonCodec<Annotations> {
+
+    @Override
+    public ObjectNode encode(Annotations annotations, CodecContext context) {
+        ObjectNode result = context.mapper().createObjectNode();
+        for (String key : annotations.keys()) {
+            result.put(key, annotations.value(key));
+        }
+        return result;
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/CodecManager.java b/web/api/src/main/java/org/onlab/onos/codec/impl/CodecManager.java
new file mode 100644
index 0000000..30be730
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/CodecManager.java
@@ -0,0 +1,86 @@
+/*
+ * 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.codec.impl;
+
+import com.google.common.collect.ImmutableSet;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Service;
+import org.onlab.onos.codec.CodecService;
+import org.onlab.onos.codec.JsonCodec;
+import org.onlab.onos.net.Annotations;
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.Device;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.Port;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Implementation of the JSON codec brokering service.
+ */
+@Component(immediate = true)
+@Service
+public class CodecManager implements CodecService {
+
+    private static Logger log = LoggerFactory.getLogger(CodecManager.class);
+
+    private final Map<Class<?>, JsonCodec> codecs = new ConcurrentHashMap<>();
+
+    @Activate
+    public void activate() {
+        codecs.clear();
+        registerCodec(Annotations.class, new AnnotationsCodec());
+        registerCodec(Device.class, new DeviceCodec());
+        registerCodec(Port.class, new PortCodec());
+        registerCodec(ConnectPoint.class, new ConnectPointCodec());
+        registerCodec(Link.class, new LinkCodec());
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deativate() {
+        codecs.clear();
+        log.info("Stopped");
+    }
+
+    @Override
+    public Set<Class<?>> getCodecs() {
+        return ImmutableSet.copyOf(codecs.keySet());
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public <T> JsonCodec<T> getCodec(Class<T> entityClass) {
+        return codecs.get(entityClass);
+    }
+
+    @Override
+    public <T> void registerCodec(Class<T> entityClass, JsonCodec<T> codec) {
+        codecs.putIfAbsent(entityClass, codec);
+    }
+
+    @Override
+    public void unregisterCodec(Class<?> entityClass) {
+        codecs.remove(entityClass);
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/ConnectPointCodec.java b/web/api/src/main/java/org/onlab/onos/codec/impl/ConnectPointCodec.java
new file mode 100644
index 0000000..3b5bf02
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/ConnectPointCodec.java
@@ -0,0 +1,38 @@
+/*
+ * 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.codec.impl;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.onos.codec.CodecContext;
+import org.onlab.onos.codec.JsonCodec;
+import org.onlab.onos.net.ConnectPoint;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Connection point JSON codec.
+ */
+public class ConnectPointCodec extends JsonCodec<ConnectPoint> {
+
+    @Override
+    public ObjectNode encode(ConnectPoint point, CodecContext context) {
+        checkNotNull(point, "Connect point cannot be null");
+        return context.mapper().createObjectNode()
+                .put("device", point.deviceId().toString())
+                .put("port", point.port().toString());
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/DeviceCodec.java b/web/api/src/main/java/org/onlab/onos/codec/impl/DeviceCodec.java
new file mode 100644
index 0000000..5835382
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/DeviceCodec.java
@@ -0,0 +1,45 @@
+/*
+ * 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.codec.impl;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.onos.codec.CodecContext;
+import org.onlab.onos.net.Device;
+import org.onlab.onos.net.device.DeviceService;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Device JSON codec.
+ */
+public class DeviceCodec extends AnnotatedCodec<Device> {
+
+    @Override
+    public ObjectNode encode(Device device, CodecContext context) {
+        checkNotNull(device, "Device cannot be null");
+        DeviceService service = context.get(DeviceService.class);
+        ObjectNode result = context.mapper().createObjectNode()
+                .put("id", device.id().toString())
+                .put("available", service.isAvailable(device.id()))
+                .put("role", service.getRole(device.id()).toString())
+                .put("mfr", device.manufacturer())
+                .put("hw", device.hwVersion())
+                .put("sw", device.swVersion())
+                .put("serial", device.serialNumber());
+        return annotate(result, device, context);
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/LinkCodec.java b/web/api/src/main/java/org/onlab/onos/codec/impl/LinkCodec.java
new file mode 100644
index 0000000..ad09663
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/LinkCodec.java
@@ -0,0 +1,43 @@
+/*
+ * 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.codec.impl;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.onos.codec.CodecContext;
+import org.onlab.onos.codec.JsonCodec;
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.device.DeviceService;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Link JSON codec.
+ */
+public class LinkCodec extends AnnotatedCodec<Link> {
+
+    @Override
+    public ObjectNode encode(Link link, CodecContext context) {
+        checkNotNull(link, "Link cannot be null");
+        DeviceService service = context.get(DeviceService.class);
+        JsonCodec<ConnectPoint> codec = context.codec(ConnectPoint.class);
+        ObjectNode result = context.mapper().createObjectNode();
+        result.set("src", codec.encode(link.src(), context));
+        result.set("dst", codec.encode(link.dst(), context));
+        return annotate(result, link, context);
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/PortCodec.java b/web/api/src/main/java/org/onlab/onos/codec/impl/PortCodec.java
new file mode 100644
index 0000000..4bfcc6a
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/PortCodec.java
@@ -0,0 +1,45 @@
+/*
+ * 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.codec.impl;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.onos.codec.CodecContext;
+import org.onlab.onos.net.Port;
+import org.onlab.onos.net.PortNumber;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Device port JSON codec.
+ */
+public class PortCodec extends AnnotatedCodec<Port> {
+
+    @Override
+    public ObjectNode encode(Port port, CodecContext context) {
+        checkNotNull(port, "Port cannot be null");
+        ObjectNode result = context.mapper().createObjectNode()
+                .put("port", portName(port.number()))
+                .put("isEnabled", port.isEnabled())
+                .put("type", port.type().toString().toLowerCase())
+                .put("portSpeed", port.portSpeed());
+        return annotate(result, port, context);
+    }
+
+    private String portName(PortNumber port) {
+        return port.equals(PortNumber.LOCAL) ? "local" : port.toString();
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/codec/impl/package-info.java b/web/api/src/main/java/org/onlab/onos/codec/impl/package-info.java
new file mode 100644
index 0000000..31db517
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/codec/impl/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+/**
+ * Implementations of the codec broker and built-in entity JSON codecs.
+ */
+package org.onlab.onos.codec.impl;
\ No newline at end of file
diff --git a/web/api/src/main/java/org/onlab/onos/rest/AbstractWebResource.java b/web/api/src/main/java/org/onlab/onos/rest/AbstractWebResource.java
new file mode 100644
index 0000000..ee9adb0
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/AbstractWebResource.java
@@ -0,0 +1,81 @@
+/*
+ * 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.rest;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.api.ItemNotFoundException;
+import org.onlab.onos.codec.CodecContext;
+import org.onlab.onos.codec.CodecService;
+import org.onlab.onos.codec.JsonCodec;
+import org.onlab.rest.BaseResource;
+
+/**
+ * Abstract REST resource.
+ */
+public class AbstractWebResource extends BaseResource implements CodecContext {
+
+    @Override
+    public ObjectMapper mapper() {
+        return new ObjectMapper();
+    }
+
+    /**
+     * Returns the JSON codec for the specified entity class.
+     *
+     * @param entityClass entity class
+     * @param <T>         entity type
+     * @return JSON codec
+     */
+    public <T> JsonCodec<T> codec(Class<T> entityClass) {
+        return get(CodecService.class).getCodec(entityClass);
+    }
+
+    /**
+     * Returns JSON object wrapping the array encoding of the specified
+     * collection of items.
+     *
+     * @param codecClass codec item class
+     * @param field      field holding the array
+     * @param items      collection of items to be encoded into array
+     * @param <T>        item type
+     * @return JSON object
+     */
+    protected <T> ObjectNode encodeArray(Class<T> codecClass, String field,
+                                         Iterable<T> items) {
+        ObjectNode result = mapper().createObjectNode();
+        result.set(field, codec(codecClass).encode(items, this));
+        return result;
+    }
+
+    /**
+     * Returns the specified item if that items is null; otherwise throws
+     * not found exception.
+     *
+     * @param item    item to check
+     * @param message not found message
+     * @param <T>     item type
+     * @return item if not null
+     * @throws org.onlab.api.ItemNotFoundException if item is null
+     */
+    protected <T> T nullIsNotFound(T item, String message) {
+        if (item == null) {
+            throw new ItemNotFoundException(message);
+        }
+        return item;
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/DevicesWebResource.java b/web/api/src/main/java/org/onlab/onos/rest/DevicesWebResource.java
new file mode 100644
index 0000000..52fca58
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/DevicesWebResource.java
@@ -0,0 +1,65 @@
+/*
+ * 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.rest;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.onos.net.Device;
+import org.onlab.onos.net.Port;
+import org.onlab.onos.net.device.DeviceService;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.core.Response;
+import java.util.List;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.onlab.onos.net.DeviceId.deviceId;
+
+/**
+ * REST resource for interacting with the inventory of infrastructure devices.
+ */
+@Path("devices")
+public class DevicesWebResource extends AbstractWebResource {
+
+    public static final String DEVICE_NOT_FOUND = "Device is not found";
+
+    @GET
+    public Response getDevices() {
+        Iterable<Device> devices = get(DeviceService.class).getDevices();
+        return ok(encodeArray(Device.class, "devices", devices)).build();
+    }
+
+    @GET
+    @Path("{id}")
+    public Response getDevice(@PathParam("id") String id) {
+        Device device = nullIsNotFound(get(DeviceService.class).getDevice(deviceId(id)),
+                                       DEVICE_NOT_FOUND);
+        return ok(codec(Device.class).encode(device, this)).build();
+    }
+
+    @GET
+    @Path("{id}/ports")
+    public Response getDevicePorts(@PathParam("id") String id) {
+        DeviceService service = get(DeviceService.class);
+        Device device = nullIsNotFound(service.getDevice(deviceId(id)), DEVICE_NOT_FOUND);
+        List<Port> ports = checkNotNull(service.getPorts(deviceId(id)), "Ports could not be retrieved");
+        ObjectNode result = codec(Device.class).encode(device, this);
+        result.set("ports", codec(Port.class).encode(ports, this));
+        return ok(result).build();
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/JsonBodyWriter.java b/web/api/src/main/java/org/onlab/onos/rest/JsonBodyWriter.java
new file mode 100644
index 0000000..d34e30e
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/JsonBodyWriter.java
@@ -0,0 +1,58 @@
+/*
+ * 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.rest;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+import javax.ws.rs.Produces;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.MultivaluedMap;
+import javax.ws.rs.ext.MessageBodyWriter;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Type;
+
+/**
+ * JAX-RS Response message body writer.
+ */
+@Produces("application/json")
+public class JsonBodyWriter implements MessageBodyWriter<ObjectNode> {
+
+    private ObjectMapper mapper = new ObjectMapper();
+
+    @Override
+    public boolean isWriteable(Class<?> type, Type genericType,
+                               Annotation[] annotations, MediaType mediaType) {
+        return type == ObjectNode.class;
+    }
+
+    @Override
+    public long getSize(ObjectNode node, Class<?> type, Type genericType,
+                        Annotation[] annotations, MediaType mediaType) {
+        return -1;
+    }
+
+    @Override
+    public void writeTo(ObjectNode node, Class<?> type, Type genericType,
+                        Annotation[] annotations, MediaType mediaType,
+                        MultivaluedMap<String, Object> httpHeaders,
+                        OutputStream entityStream) throws IOException {
+        mapper.writer().writeValue(entityStream, node);
+        entityStream.flush();
+    }
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/LinksWebResource.java b/web/api/src/main/java/org/onlab/onos/rest/LinksWebResource.java
new file mode 100644
index 0000000..479b6a0
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/LinksWebResource.java
@@ -0,0 +1,89 @@
+/*
+ * 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.rest;
+
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.link.LinkService;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.QueryParam;
+import javax.ws.rs.core.Response;
+
+import static org.onlab.onos.net.DeviceId.deviceId;
+import static org.onlab.onos.net.PortNumber.portNumber;
+import static org.onlab.onos.rest.LinksWebResource.Direction.valueOf;
+
+/**
+ * REST resource for interacting with the inventory of infrastructure links.
+ */
+@Path("links")
+public class LinksWebResource extends AbstractWebResource {
+
+    enum Direction { ALL, INGRESS, EGRESS }
+
+    @GET
+    public Response getLinks(@QueryParam("device") String deviceId,
+                             @QueryParam("port") String port,
+                             @QueryParam("direction") String direction) {
+        LinkService service = get(LinkService.class);
+        Iterable<Link> links;
+
+        if (deviceId != null && port != null) {
+            links = getConnectPointLinks(new ConnectPoint(deviceId(deviceId),
+                                                          portNumber(port)),
+                                         direction, service);
+        } else if (deviceId != null) {
+            links = getDeviceLinks(deviceId(deviceId), direction, service);
+        } else {
+            links = service.getLinks();
+        }
+        return ok(encodeArray(Link.class, "links", links)).build();
+    }
+
+    private Iterable<Link> getConnectPointLinks(ConnectPoint point,
+                                                String direction,
+                                                LinkService service) {
+        Direction dir = direction != null ?
+                valueOf(direction.toUpperCase()) : Direction.ALL;
+        switch (dir) {
+            case INGRESS:
+                return service.getIngressLinks(point);
+            case EGRESS:
+                return service.getEgressLinks(point);
+            default:
+                return service.getLinks(point);
+        }
+    }
+
+    private Iterable<Link> getDeviceLinks(DeviceId deviceId,
+                                          String direction,
+                                          LinkService service) {
+        Direction dir = direction != null ?
+                valueOf(direction.toUpperCase()) : Direction.ALL;
+        switch (dir) {
+            case INGRESS:
+                return service.getDeviceIngressLinks(deviceId);
+            case EGRESS:
+                return service.getDeviceEgressLinks(deviceId);
+            default:
+                return service.getDeviceLinks(deviceId);
+        }
+    }
+
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/exceptions/AbstractMapper.java b/web/api/src/main/java/org/onlab/onos/rest/exceptions/AbstractMapper.java
new file mode 100644
index 0000000..50c27ae
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/exceptions/AbstractMapper.java
@@ -0,0 +1,57 @@
+/*
+ * 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.rest.exceptions;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.ExceptionMapper;
+
+/**
+ * Base exception mapper implementation.
+ */
+public abstract class AbstractMapper<E extends Throwable> implements ExceptionMapper<E> {
+
+    /**
+     * Returns the response status to be given when the exception occurs.
+     *
+     * @return response status
+     */
+    protected abstract Response.Status responseStatus();
+
+    @Override
+    public Response toResponse(E exception) {
+        return response(responseStatus(), exception).build();
+    }
+
+    /**
+     * Produces a response builder primed with the supplied status code
+     * and JSON entity with the status code and exception message.
+     *
+     * @param status    response status
+     * @param exception exception to encode
+     * @return response builder
+     */
+    protected Response.ResponseBuilder response(Response.Status status,
+                                                Throwable exception) {
+        ObjectMapper mapper = new ObjectMapper();
+        ObjectNode result = mapper.createObjectNode()
+                .put("code", status.getStatusCode())
+                .put("message", exception.getMessage());
+        return Response.status(status).entity(result.toString());
+    }
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/exceptions/EntityNotFoundMapper.java b/web/api/src/main/java/org/onlab/onos/rest/exceptions/EntityNotFoundMapper.java
new file mode 100644
index 0000000..4c86fe6
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/exceptions/EntityNotFoundMapper.java
@@ -0,0 +1,30 @@
+/*
+ * 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.rest.exceptions;
+
+import org.onlab.api.ItemNotFoundException;
+
+import javax.ws.rs.core.Response;
+
+/**
+ * Mapper for service not found exceptions to the NOT_FOUND response code.
+ */
+public class EntityNotFoundMapper extends AbstractMapper<ItemNotFoundException> {
+    @Override
+    protected Response.Status responseStatus() {
+        return Response.Status.NOT_FOUND;
+    }
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/exceptions/ServerErrorMapper.java b/web/api/src/main/java/org/onlab/onos/rest/exceptions/ServerErrorMapper.java
new file mode 100644
index 0000000..a9d95d0
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/exceptions/ServerErrorMapper.java
@@ -0,0 +1,28 @@
+/*
+ * 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.rest.exceptions;
+
+import javax.ws.rs.core.Response;
+
+/**
+ * Mapper for service not found exceptions to the NOT_FOUND response code.
+ */
+public class ServerErrorMapper extends AbstractMapper<RuntimeException> {
+    @Override
+    protected Response.Status responseStatus() {
+        return Response.Status.INTERNAL_SERVER_ERROR;
+    }
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/exceptions/ServiceNotFoundMapper.java b/web/api/src/main/java/org/onlab/onos/rest/exceptions/ServiceNotFoundMapper.java
new file mode 100644
index 0000000..297882b
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/exceptions/ServiceNotFoundMapper.java
@@ -0,0 +1,30 @@
+/*
+ * 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.rest.exceptions;
+
+import org.onlab.osgi.ServiceNotFoundException;
+
+import javax.ws.rs.core.Response;
+
+/**
+ * Mapper for service not found exceptions to the SERVICE_UNAVAILABLE response code.
+ */
+public class ServiceNotFoundMapper extends AbstractMapper<ServiceNotFoundException> {
+    @Override
+    protected Response.Status responseStatus() {
+        return Response.Status.SERVICE_UNAVAILABLE;
+    }
+}
diff --git a/web/api/src/main/java/org/onlab/onos/rest/exceptions/package-info.java b/web/api/src/main/java/org/onlab/onos/rest/exceptions/package-info.java
new file mode 100644
index 0000000..5f733e7
--- /dev/null
+++ b/web/api/src/main/java/org/onlab/onos/rest/exceptions/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+/**
+ * Various exception mappers to map errors to proper response status codes.
+ */
+package org.onlab.onos.rest.exceptions;
\ No newline at end of file
diff --git a/web/api/src/main/webapp/WEB-INF/web.xml b/web/api/src/main/webapp/WEB-INF/web.xml
index c634728..1342203 100644
--- a/web/api/src/main/webapp/WEB-INF/web.xml
+++ b/web/api/src/main/webapp/WEB-INF/web.xml
@@ -24,8 +24,21 @@
         <servlet-name>JAX-RS Service</servlet-name>
         <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
         <init-param>
-            <param-name>com.sun.jersey.config.property.packages</param-name>
-            <param-value>org.onlab.onos.rest</param-value>
+            <param-name>com.sun.jersey.config.property.resourceConfigClass</param-name>
+            <param-value>com.sun.jersey.api.core.ClassNamesResourceConfig</param-value>
+        </init-param>
+        <init-param>
+            <param-name>com.sun.jersey.config.property.classnames</param-name>
+            <param-value>
+                org.onlab.onos.rest.exceptions.EntityNotFoundMapper,
+                org.onlab.onos.rest.exceptions.ServiceNotFoundMapper,
+                org.onlab.onos.rest.exceptions.ServerErrorMapper,
+                org.onlab.onos.rest.JsonBodyWriter,
+
+                org.onlab.onos.rest.DevicesWebResource,
+                org.onlab.onos.rest.LinksWebResource,
+                org.onlab.onos.rest.ConfigResource
+            </param-value>
         </init-param>
         <load-on-startup>1</load-on-startup>
     </servlet>
diff --git a/web/pom.xml b/web/pom.xml
index 0efbd59..f846078 100644
--- a/web/pom.xml
+++ b/web/pom.xml
@@ -109,6 +109,10 @@
         <plugins>
             <plugin>
                 <groupId>org.apache.felix</groupId>
+                <artifactId>maven-scr-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.felix</groupId>
                 <artifactId>maven-bundle-plugin</artifactId>
                 <extensions>true</extensions>
                 <configuration>
@@ -120,13 +124,15 @@
                         <Import-Package>
                             org.slf4j,
                             org.osgi.framework,
-                            javax.ws.rs,javax.ws.rs.core,
+                            javax.ws.rs,javax.ws.rs.core,javax.ws.rs.ext,
                             com.sun.jersey.api.core,
                             com.sun.jersey.spi.container.servlet,
                             com.sun.jersey.server.impl.container.servlet,
                             com.fasterxml.jackson.databind,
                             com.fasterxml.jackson.databind.node,
                             com.google.common.base.*,
+                            org.onlab.api.*,
+                            org.onlab.osgi.*,
                             org.onlab.packet.*,
                             org.onlab.rest.*,
                             org.onlab.onos.*