Polling link provider

    The provider is capable of polling the environment using the
    device driver behaviour (LinkDiscovery)

Change-Id: Ia09f866299d38c4de9b13201c9cf63b03909164a

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.net.behaviour;
+
+import org.onosproject.net.driver.HandlerBehaviour;
+import org.onosproject.net.link.LinkDescription;
+
+import java.util.Set;
+
+/**
+ * A HandlerBehaviour to discover links.
+ */
+public interface LinkDiscovery extends HandlerBehaviour {
+
+
+    /**
+     * Returns set of discovered {@link LinkDescription}.
+     * @return set of LinkDescription.
+     */
+    Set<LinkDescription> getLinks();
+}
\ No newline at end of file

+COMPILE_DEPS = [
+    '//lib:CORE_DEPS',
+]
+
+TEST_DEPS = [
+    '//lib:TEST_ADAPTERS',
+    '//utils/osgi:onlab-osgi-tests',
+]
+
+osgi_jar_with_tests (
+    deps = COMPILE_DEPS,
+    test_deps = TEST_DEPS,
+)
+
+onos_app (
+  app_name = 'org.onosproject.linkdiscovery',
+  title = 'Link Discovery Provider',
+  category = 'Provider',
+  url = 'http://onosproject.org',
+  description = 'ONOS link discovery provider.',
+)
\ No newline at end of file

+<?xml version="1.0" encoding="UTF-8"?>
+
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<app name="org.onosproject.linkdiscovery" origin="acino.eu" version="${project.version}"
+     category="Provider" url="http://onosproject.org" title="ONOS link discovery provider"
+     featuresRepo="mvn:${project.groupId}/${project.artifactId}/${project.version}/xml/features"
+     features="${project.artifactId}">
+    <description>${project.description}</description>
+    <artifact>mvn:${project.groupId}/onos-linkdiscovery-provider/${project.version}</artifact>
+</app>

+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  --><features xmlns="http://karaf.apache.org/xmlns/features/v1.2.0" name="${project.artifactId}-${project.version}">
+    <feature name="${project.artifactId}" version="${project.version}"
+             description="${project.description}">
+        <feature>onos-api</feature>
+        <bundle>mvn:${project.groupId}/onos-linkdiscovery-provider/${project.version}</bundle>
+    </feature>
+</features>
+

+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.onosproject</groupId>
+        <artifactId>onos-providers</artifactId>
+        <version>1.7.0-SNAPSHOT</version>
+    </parent>
+
+
+    <artifactId>onos-linkdiscovery-provider</artifactId>
+    <packaging>bundle</packaging>
+
+    <properties>
+        <onos.app.name>org.onosproject.linkdiscovery</onos.app.name>
+        <onos.app.title>Link Discovery Provider</onos.app.title>
+        <onos.app.origin>acino.eu</onos.app.origin>
+        <onos.app.category>Provider</onos.app.category>
+        <onos.app.readme>ONOS link discovery provider.</onos.app.readme>
+    </properties>
+
+    <description>ONOS link discovery provider</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.osgi</groupId>
+            <artifactId>org.osgi.compendium</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onlab-osgi</artifactId>
+            <version>${project.version}</version>
+            <classifier>tests</classifier>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onlab-junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.easymock</groupId>
+            <artifactId>easymock</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onos-api</artifactId>
+            <classifier>tests</classifier>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.provider.linkdiscovery.impl;
+
+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.Modified;
+import org.apache.felix.scr.annotations.Property;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.cfg.ComponentConfigService;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.net.AnnotationKeys;
+import org.onosproject.net.DefaultAnnotations;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Link;
+import org.onosproject.net.behaviour.LinkDiscovery;
+import org.onosproject.net.device.DeviceEvent;
+import org.onosproject.net.device.DeviceListener;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.link.DefaultLinkDescription;
+import org.onosproject.net.link.LinkDescription;
+import org.onosproject.net.link.LinkProvider;
+import org.onosproject.net.link.LinkProviderRegistry;
+import org.onosproject.net.link.LinkProviderService;
+import org.onosproject.net.link.LinkService;
+import org.onosproject.net.provider.AbstractProvider;
+import org.onosproject.net.provider.ProviderId;
+import org.osgi.service.component.ComponentContext;
+import org.slf4j.Logger;
+
+import java.util.Dictionary;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.stream.Collectors;
+
+import static com.google.common.base.Strings.isNullOrEmpty;
+import static java.util.concurrent.Executors.newScheduledThreadPool;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.onlab.util.Tools.get;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Link provider capable of polling the environment using the device driver
+ * {@link LinkDiscovery} behaviour.
+ */
+@Component(immediate = true)
+public class LinkDiscoveryProvider extends AbstractProvider
+        implements LinkProvider {
+
+    protected static final String APP_NAME = "org.onosproject.linkdiscovery";
+    protected static final String SCHEME_NAME = "linkdiscovery";
+    private static final String LINK_PROVIDER_PACKAGE = "org.onosproject.provider.linkdiscovery";
+    private final Logger log = getLogger(getClass());
+    private static final int DEFAULT_POLL_DELAY_SECONDS = 20;
+    @Property(name = "linkPollDelaySeconds", intValue = DEFAULT_POLL_DELAY_SECONDS,
+            label = "Initial delay (in seconds) for polling link discovery")
+    protected static int linkPollDelaySeconds = DEFAULT_POLL_DELAY_SECONDS;
+    private static final int DEFAULT_POLL_FREQUENCY_SECONDS = 10;
+    @Property(name = "linkPollFrequencySeconds", intValue = DEFAULT_POLL_FREQUENCY_SECONDS,
+            label = "Frequency (in seconds) for polling link discovery")
+    protected static int linkPollFrequencySeconds = DEFAULT_POLL_FREQUENCY_SECONDS;
+
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected LinkProviderRegistry providerRegistry;
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected CoreService coreService;
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected LinkService linkService;
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected MastershipService mastershipService;
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+    protected ScheduledExecutorService executor =
+            newScheduledThreadPool(2, groupedThreads("onos/netconf-link",
+                                                     "discovery-%d"));
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ComponentConfigService cfgService;
+
+    protected LinkProviderService providerService;
+    private InternalDeviceListener deviceListener = new InternalDeviceListener();
+    private ApplicationId appId;
+    private ScheduledFuture<?> scheduledTask;
+
+    /**
+     * Creates a provider with the supplied identifier.
+     */
+    public LinkDiscoveryProvider() {
+        super(new ProviderId(SCHEME_NAME, LINK_PROVIDER_PACKAGE));
+    }
+
+    @Activate
+    public void activate(ComponentContext context) {
+        providerService = providerRegistry.register(this);
+        appId = coreService.registerApplication(APP_NAME);
+        deviceService.addListener(deviceListener);
+        cfgService.registerProperties(getClass());
+
+        if (context == null) {
+            linkPollFrequencySeconds = DEFAULT_POLL_FREQUENCY_SECONDS;
+            log.info("No component configuration");
+        } else {
+            Dictionary<?, ?> properties = context.getProperties();
+            linkPollFrequencySeconds =
+                    getNewPollFrequency(properties, linkPollFrequencySeconds);
+        }
+        scheduledTask = schedulePolling();
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        cfgService.unregisterProperties(getClass(), false);
+        deviceService.removeListener(deviceListener);
+        providerRegistry.unregister(this);
+        providerService = null;
+        scheduledTask.cancel(true);
+        executor.shutdown();
+        log.info("Stopped");
+    }
+
+    @Modified
+    public void modified(ComponentContext context) {
+        if (context == null) {
+            log.info("No component configuration");
+            return;
+        } else {
+            Dictionary<?, ?> properties = context.getProperties();
+
+            int newPollFrequency = getNewPollFrequency(properties, linkPollFrequencySeconds);
+            int newPollDelay = getNewPollDealy(properties, linkPollDelaySeconds);
+            if (newPollFrequency != linkPollFrequencySeconds ||
+                    newPollDelay != linkPollDelaySeconds) {
+                linkPollFrequencySeconds = newPollFrequency;
+                linkPollDelaySeconds = newPollDelay;
+                //stops the old scheduled task
+                scheduledTask.cancel(true);
+                //schedules new task at the new polling rate
+                scheduledTask = schedulePolling();
+            }
+        }
+        log.info("Modified");
+    }
+
+    private int getNewPollFrequency(Dictionary<?, ?> properties, int pollFrequency) {
+        int newPollFrequency;
+        try {
+            String s = get(properties, "linkPollFrequencySeconds");
+            newPollFrequency = isNullOrEmpty(s) ? pollFrequency : Integer.parseInt(s.trim());
+        } catch (NumberFormatException | ClassCastException e) {
+            newPollFrequency = DEFAULT_POLL_FREQUENCY_SECONDS;
+        }
+        return newPollFrequency;
+    }
+
+    private int getNewPollDealy(Dictionary<?, ?> properties, int pollDelay) {
+        int newPollFrequency;
+        try {
+            String s = get(properties, "linkPollDelaySeconds");
+            newPollFrequency = isNullOrEmpty(s) ? pollDelay : Integer.parseInt(s.trim());
+        } catch (NumberFormatException | ClassCastException e) {
+            newPollFrequency = DEFAULT_POLL_DELAY_SECONDS;
+        }
+        return newPollFrequency;
+    }
+
+    private ScheduledFuture schedulePolling() {
+        return executor.scheduleAtFixedRate(this::discoverLinksTasks,
+                                            linkPollDelaySeconds,
+                                            linkPollFrequencySeconds,
+                                            SECONDS);
+    }
+
+    private void discoverLinksTasks() {
+        deviceService.getAvailableDevices().forEach(device -> {
+            if (isSupported(device)) {
+                evaluateLinks(device.id(), device.as(LinkDiscovery.class).getLinks());
+            }
+        });
+    }
+
+    private void evaluateLinks(DeviceId deviceId, Set<LinkDescription> discoveredLinksDesc) {
+        //The provider will get only existing links related to LinkDiscovery
+        Set<Link> storedLinks = linkService.getDeviceEgressLinks(deviceId)
+                .stream()
+                .filter(link -> {
+                    String value = link.annotations().value(AnnotationKeys.PROTOCOL);
+                    if (value != null && value.equals(SCHEME_NAME.toUpperCase())) {
+                        return true;
+                    }
+                    return false;
+                })
+                .collect(Collectors.toSet());
+
+        //Convert Link to LinkDescription for comparison
+        Set<LinkDescription> storedLinkDescs = new HashSet<>();
+        storedLinks.forEach(link -> storedLinkDescs
+                .add(new DefaultLinkDescription(
+                        link.src(), link.dst(), link.type(), link.isExpected(),
+                        DefaultAnnotations.builder().putAll(link.annotations()).build())));
+        log.debug("Current stored links provider related {}", storedLinks);
+
+        //Add the correct annotation for comparison
+        Set<LinkDescription> discoveredLinkDescsAnn = new HashSet<>();
+
+        discoveredLinksDesc.forEach(linkDesc -> discoveredLinkDescsAnn
+                .add(new DefaultLinkDescription(
+                        linkDesc.src(), linkDesc.dst(), linkDesc.type(), false,
+                        DefaultAnnotations.builder().putAll(linkDesc.annotations())
+                                .set(AnnotationKeys.PROTOCOL, SCHEME_NAME.toUpperCase())
+                                .build())));
+
+        Set<LinkDescription> linkDescsToBeRemoved = new HashSet<>(storedLinkDescs);
+        linkDescsToBeRemoved.removeAll(discoveredLinkDescsAnn);
+        log.debug("Links to be removed {}", linkDescsToBeRemoved);
+        linkDescsToBeRemoved.forEach(linkDesc ->
+                                             providerService.linkVanished(linkDesc));
+
+        Set<LinkDescription> linksToBeAdded = new HashSet<>(discoveredLinkDescsAnn);
+        linksToBeAdded.removeAll(storedLinkDescs);
+        log.debug("Links to be added {}", linksToBeAdded);
+        linksToBeAdded.forEach(linkDesc -> providerService.linkDetected(linkDesc)
+        );
+    }
+
+    protected boolean isSupported(Device device) {
+        boolean supported = mastershipService.isLocalMaster(device.id())
+                && device.is(LinkDiscovery.class);
+        if (!supported) {
+            log.debug("Device {} does not support LinkDiscovery", device);
+        }
+        return supported;
+    }
+
+    /**
+     * Listener for core device events.
+     */
+    private class InternalDeviceListener implements DeviceListener {
+        @Override
+        public void event(DeviceEvent event) {
+            if ((event.type() == DeviceEvent.Type.DEVICE_ADDED)) {
+                executor.execute(() -> event.subject().as(LinkDiscovery.class).getLinks()
+                        .forEach(linkDesc -> {
+                            providerService.linkDetected(new DefaultLinkDescription(
+                                    linkDesc.src(), linkDesc.dst(), linkDesc.type(), false,
+                                    DefaultAnnotations.builder()
+                                            .putAll(linkDesc.annotations())
+                                            .set(AnnotationKeys.PROTOCOL, SCHEME_NAME.toUpperCase())
+                                            .build()));
+                        }));
+            }
+        }
+
+        @Override
+        public boolean isRelevant(DeviceEvent event) {
+            return isSupported(event.subject());
+        }
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Provider that uses LinkDiscovery {@link org.onosproject.net.behaviour.LinkDiscovery}
+ * to poll the network environment as a means of link discovery.
+ */
+package org.onosproject.provider.linkdiscovery.impl;
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.provider.linkdiscovery.impl;
+
+import com.google.common.collect.ImmutableSet;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.osgi.ComponentContextAdapter;
+import org.onlab.packet.ChassisId;
+import org.onosproject.cfg.ComponentConfigAdapter;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.core.DefaultApplicationId;
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.mastership.MastershipServiceAdapter;
+import org.onosproject.net.AbstractProjectableModel;
+import org.onosproject.net.AnnotationKeys;
+import org.onosproject.net.Annotations;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DefaultAnnotations;
+import org.onosproject.net.DefaultDevice;
+import org.onosproject.net.DefaultLink;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Link;
+import org.onosproject.net.LinkKey;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.behaviour.LinkDiscovery;
+import org.onosproject.net.device.DeviceListener;
+import org.onosproject.net.device.DeviceServiceAdapter;
+import org.onosproject.net.driver.AbstractHandlerBehaviour;
+import org.onosproject.net.driver.Behaviour;
+import org.onosproject.net.driver.Driver;
+import org.onosproject.net.driver.DriverAdapter;
+import org.onosproject.net.driver.DriverHandler;
+import org.onosproject.net.driver.DriverServiceAdapter;
+import org.onosproject.net.link.DefaultLinkDescription;
+import org.onosproject.net.link.LinkDescription;
+import org.onosproject.net.link.LinkProviderRegistryAdapter;
+import org.onosproject.net.link.LinkProviderServiceAdapter;
+import org.onosproject.net.link.LinkServiceAdapter;
+import org.onosproject.net.provider.ProviderId;
+
+import java.util.Dictionary;
+import java.util.HashSet;
+import java.util.Hashtable;
+import java.util.Set;
+
+import static org.easymock.EasyMock.*;
+import static org.junit.Assert.*;
+import static org.onlab.junit.TestTools.assertAfter;
+import static org.onosproject.provider.linkdiscovery.impl.LinkDiscoveryProvider.APP_NAME;
+import static org.onosproject.provider.linkdiscovery.impl.LinkDiscoveryProvider.SCHEME_NAME;
+
+/**
+ * Test for polling mechanism of the NetconfLinkProvider.
+ */
+public class LinkDiscoveryProviderTest {
+
+    private static final ComponentContextAdapter CONTEXT =
+            new ComponentContextAdapter() {
+                @Override
+                public Dictionary getProperties() {
+                    Hashtable<String, Integer> props = new Hashtable<>();
+                    props.put("linkPollFrequencySeconds", 2);
+                    props.put("linkPollDelaySeconds", 1);
+                    return props;
+                }
+            };
+    // Network Mocks
+    private static final DeviceId DEVICE_ID_1 = DeviceId.deviceId("netconf:1.1.1.1");
+    private static final DeviceId DEVICE_ID_2 = DeviceId.deviceId("netconf:1.1.1.2");
+    private static final ConnectPoint CP11 = new ConnectPoint(DEVICE_ID_1, PortNumber.portNumber(1));
+    private static final ConnectPoint CP12 = new ConnectPoint(DEVICE_ID_1, PortNumber.portNumber(2));
+    private static final ConnectPoint CP13 = new ConnectPoint(DEVICE_ID_1, PortNumber.portNumber(3));
+    private static final ConnectPoint CP14 = new ConnectPoint(DEVICE_ID_1, PortNumber.portNumber(4));
+    private static final ConnectPoint CP21 = new ConnectPoint(DEVICE_ID_2, PortNumber.portNumber(1));
+    private static final ConnectPoint CP22 = new ConnectPoint(DEVICE_ID_2, PortNumber.portNumber(2));
+    private static final ConnectPoint CP23 = new ConnectPoint(DEVICE_ID_2, PortNumber.portNumber(3));
+    private static final ConnectPoint CP24 = new ConnectPoint(DEVICE_ID_2, PortNumber.portNumber(4));
+    private static final DefaultAnnotations DEVICE_ANNOTATIONS = DefaultAnnotations.builder()
+            .set(AnnotationKeys.PROTOCOL, SCHEME_NAME.toUpperCase()).build();
+    private static final DefaultAnnotations LINK_ANNOTATIONS = DefaultAnnotations.builder()
+            .set(AnnotationKeys.PROTOCOL, SCHEME_NAME.toUpperCase()).build();
+    private static final LinkKey LINKKEY1 = LinkKey.linkKey(CP11, CP21);
+    private static final LinkDescription LINK1 = new DefaultLinkDescription(CP11, CP21,
+                                                                            Link.Type.DIRECT,
+                                                                            LINK_ANNOTATIONS);
+    private static final LinkKey LINKKEY2 = LinkKey.linkKey(CP12, CP22);
+    private static final LinkDescription LINK2 = new DefaultLinkDescription(CP12, CP22,
+                                                                            Link.Type.DIRECT,
+                                                                            LINK_ANNOTATIONS);
+    private static final LinkKey LINKKEY3 = LinkKey.linkKey(CP13, CP23);
+    private static final LinkDescription LINK3 = new DefaultLinkDescription(CP13, CP23,
+                                                                            Link.Type.DIRECT,
+                                                                            DefaultAnnotations.builder()
+                                                                                    .build());
+    private static final LinkKey LINKKEY4 = LinkKey.linkKey(CP14, CP24);
+    private static final LinkDescription LINK4 = new DefaultLinkDescription(CP14, CP24,
+                                                                            Link.Type.DIRECT,
+                                                                            DefaultAnnotations.builder().build());
+    //Service Mocks
+    private final MockDeviceService deviceService = new MockDeviceService();
+    private final LinkProviderRegistryAdapter linkRegistry = new LinkProviderRegistryAdapter();
+    private final MastershipService mastershipService = new MockMastershipService();
+    private final MockLinkService linkService = new MockLinkService();
+    private final Driver driver = new MockDriver();
+    //Provider related classes
+    private LinkProviderServiceAdapter providerService;
+    private CoreService coreService;
+    private LinkDiscoveryProvider provider = new LinkDiscoveryProvider();
+    private final Device device1 = new MockDevice(provider.id(), DEVICE_ID_1, Device.Type.SWITCH,
+                                                  "foo.inc", "0", "0", "0", new ChassisId(),
+                                                  DEVICE_ANNOTATIONS);
+    private Set<DeviceListener> deviceListeners = new HashSet<>();
+    private ApplicationId appId =
+            new DefaultApplicationId(100, APP_NAME);
+    private TestLink testLink = new TestLink();
+
+    @Before
+    public void setUp() {
+        coreService = createMock(CoreService.class);
+        expect(coreService.registerApplication(appId.name()))
+                .andReturn(appId).anyTimes();
+        replay(coreService);
+        provider.coreService = coreService;
+        provider.providerRegistry = linkRegistry;
+        provider.deviceService = deviceService;
+        provider.mastershipService = mastershipService;
+        provider.linkService = linkService;
+        provider.cfgService = new ComponentConfigAdapter();
+        AbstractProjectableModel.setDriverService(null, new DriverServiceAdapter());
+        provider.activate(null);
+        providerService = linkRegistry.registeredProvider();
+    }
+
+    @Test
+    public void activate() throws Exception {
+        assertFalse("Provider should be registered", linkRegistry.getProviders().contains(provider));
+        assertEquals("Device service should be registered", provider.deviceService, deviceService);
+        assertEquals("Device listener should be added", 1, deviceListeners.size());
+        assertNotNull("Registration expected", providerService);
+        assertEquals("Incorrect  provider", provider, providerService.provider());
+        assertFalse("Executor should be running", provider.executor.isShutdown());
+        assertFalse("Executor should be running", provider.executor.isTerminated());
+        assertEquals("Incorrect polling frequency, should be default", 10,
+                     provider.linkPollFrequencySeconds);
+        assertEquals("Incorrect polling delay , should be default", 20,
+                     provider.linkPollDelaySeconds);
+    }
+
+    @Test
+    public void modified() throws Exception {
+        provider.modified(CONTEXT);
+        assertEquals("Incorrect polling frequency, should be default", 2,
+                     provider.linkPollFrequencySeconds);
+        assertEquals("Incorrect polling delay , should be default", 1,
+                     provider.linkPollDelaySeconds);
+
+    }
+
+
+    @Test
+    public void deactivate() throws Exception {
+        provider.deactivate();
+        assertEquals("Device listener should be removed", 0, deviceListeners.size());
+        assertFalse("Provider should not be registered", linkRegistry.getProviders().contains(provider));
+        assertTrue(provider.executor.isShutdown());
+        assertNull(provider.providerService);
+    }
+
+
+    @Test
+    public void linksTestForStoredDevice() {
+        provider.modified(CONTEXT);
+        providerService.discoveredLinkDescriptions().put(LINKKEY1, LINK1);
+        providerService.discoveredLinkDescriptions().put(LINKKEY2, LINK2);
+        providerService.discoveredLinkDescriptions().put(LINKKEY4, LINK4);
+        testLink.addLinkDesc(LINK2);
+        testLink.addLinkDesc(LINK3);
+        assertAfter(1100, () -> {
+            assertEquals("Total number of link must be 3", 3, providerService.discoveredLinkDescriptions().size());
+            assertFalse("Link1 should be removed",
+                        providerService.discoveredLinkDescriptions().containsKey(LINKKEY1));
+            assertTrue("Link2 should be present",
+                       providerService.discoveredLinkDescriptions().containsKey(LINKKEY2));
+            assertTrue("Link3 should be added",
+                       providerService.discoveredLinkDescriptions().containsKey(LINKKEY3));
+            assertEquals("Link3 should be annotated", SCHEME_NAME.toUpperCase(),
+                         providerService.discoveredLinkDescriptions()
+                    .get(LINKKEY3).annotations().value(AnnotationKeys.PROTOCOL));
+            assertTrue("Link4 should be present because it is not related to the LinkDiscovery",
+                       providerService.discoveredLinkDescriptions().containsKey(LINKKEY4));
+
+        });
+        clear();
+    }
+
+    private void clear() {
+        testLink.clearLinkDesc();
+        providerService.discoveredLinkDescriptions().clear();
+        providerService.discoveredLinks().clear();
+    }
+
+    private class MockDeviceService extends DeviceServiceAdapter {
+
+        @Override
+        public Iterable<Device> getAvailableDevices() {
+            return ImmutableSet.of(device1);
+        }
+
+        @Override
+        public void addListener(DeviceListener listener) {
+            deviceListeners.add(listener);
+        }
+
+        @Override
+        public void removeListener(DeviceListener listener) {
+            deviceListeners.remove(listener);
+        }
+    }
+
+    private class MockMastershipService extends MastershipServiceAdapter {
+
+        @Override
+        public boolean isLocalMaster(DeviceId deviceId) {
+            return true;
+        }
+    }
+
+    private class MockLinkService extends LinkServiceAdapter {
+        @Override
+        public Set<Link> getDeviceEgressLinks(DeviceId deviceId) {
+            Set<Link> links = new HashSet<>();
+            providerService.discoveredLinkDescriptions().values()
+                    .forEach(x -> links.add(DefaultLink.builder()
+                                                    .providerId(provider.id())
+                                                    .src(x.src())
+                                                    .dst(x.dst())
+                                                    .type(x.type())
+                                                    .isExpected(x.isExpected())
+                                                    .annotations(x.annotations()).build()));
+            return ImmutableSet.copyOf(links);
+        }
+    }
+
+    private class MockDevice extends DefaultDevice {
+
+        public MockDevice(ProviderId providerId, DeviceId id, Type type,
+                          String manufacturer, String hwVersion, String swVersion,
+                          String serialNumber, ChassisId chassisId, Annotations... annotations) {
+            super(providerId, id, type, manufacturer, hwVersion, swVersion, serialNumber,
+                  chassisId, annotations);
+        }
+
+        @Override
+        protected Driver locateDriver() {
+            return driver;
+        }
+
+        @Override
+        public Driver driver() {
+            return driver;
+        }
+    }
+
+    private class MockDriver extends DriverAdapter {
+        @Override
+        public <T extends Behaviour> T createBehaviour(DriverHandler handler, Class<T> behaviourClass) {
+
+            return (T) testLink;
+        }
+    }
+
+    private class TestLink extends AbstractHandlerBehaviour implements LinkDiscovery {
+        Set<LinkDescription> linkDescriptions = new HashSet<>();
+
+        @Override
+        public Set<LinkDescription> getLinks() {
+            return ImmutableSet.copyOf(linkDescriptions);
+        }
+
+        private void addLinkDesc(LinkDescription link) {
+            linkDescriptions.add(link);
+        }
+
+        private void clearLinkDesc() {
+            linkDescriptions.clear();
+        }
+
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Test package for the Link Discovery Provider.
+ */
+package org.onosproject.provider.linkdiscovery.impl;
\ No newline at end of file

@@ -49,6 +49,7 @@
         <module>isis</module>
         <module>isis</module>
         <module>lisp</module>
         <module>lisp</module>
         <module>ospf</module>
         <module>ospf</module>
+        <module>link</module>
     </modules>
     </modules>
 
 
     <dependencies>
     <dependencies>