[ONOS-3203] End-to-end demo of Fault Management via SNMP.

This adds SNMP device-discovery, and a Fault Management app which makes alarms available to users via REST/GUI/CLI interfaces.
There is still code cleanup that could be done, but aim of this commit is an end-to-end proof of concept.

To demonstrate :

1) /opt/onos/bin/onos-service
onos> app activate org.onosproject.snmp
onos> app activate org.onosproject.faultmanagement

2) SNMP devices are seeded via config file. The default seed file contains connection details for devices (SNMP agents) available via internet  e.g. demo.snmplabs.com
cp /opt/onos/apache-karaf-3.0.3/etc/samples/org.onosproject.provider.snmp.device.impl.SnmpDeviceProvider.cfg   /opt/onos/apache-karaf-3.0.3/etc/

3) ONOS will poll these SNMP devices and store their alarms.

4) You can now manipulate the alarms via REST  e.g. http://<onos>:8181/onos/v1/fm/alarms , via CLI  via various "alarm-*” commands or in UI with an Alarms Overlay.

More info at https://wiki.onosproject.org/display/ONOS/Fault+Management

15/Dec/15: Updated regarding review comments from Thomas Vachuska.
17/Dec/15: Updated coreService.registerApplication(name) as per https://gerrit.onosproject.org/#/c/6878/

Change-Id: I886f8511f178dc4600ab96e5ff10cc90329cabec
diff --git a/providers/snmp/device/pom.xml b/providers/snmp/device/pom.xml
new file mode 100644
index 0000000..cf39fe4
--- /dev/null
+++ b/providers/snmp/device/pom.xml
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ ~ Copyright 2015 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-snmp-providers</artifactId>
+        <version>1.4.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>onos-snmp-provider-device</artifactId>
+    <packaging>bundle</packaging>
+
+    <description>ONOS SNMP protocol device provider</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.osgi</groupId>
+            <artifactId>org.osgi.compendium</artifactId>
+        </dependency>
+        <!--        <dependency>
+            <groupId>javax.ws.rs</groupId>
+            <artifactId>jsr311-api</artifactId>
+            <version>1.1.1</version>
+        </dependency>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onos-incubator-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onos-core-serializers</artifactId>
+            <version>${project.version}</version>
+        </dependency>-->
+    </dependencies>
+        <build>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.felix</groupId>
+                    <artifactId>maven-scr-plugin</artifactId>
+                </plugin>
+            </plugins>
+        </build>
+
+</project>
+   
\ No newline at end of file
diff --git a/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/Bti7000DeviceDescriptionProvider.java b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/Bti7000DeviceDescriptionProvider.java
new file mode 100644
index 0000000..d779e0a
--- /dev/null
+++ b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/Bti7000DeviceDescriptionProvider.java
@@ -0,0 +1,64 @@
+/*
+ * 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.snmp.device.impl;
+
+import com.btisystems.mibbler.mibs.bti7000.bti7000_13_2_0.I_Device;
+import com.btisystems.mibbler.mibs.bti7000.bti7000_13_2_0._OidRegistry;
+import com.btisystems.pronx.ems.core.model.ClassRegistry;
+import com.btisystems.pronx.ems.core.model.IClassRegistry;
+import com.btisystems.pronx.ems.core.model.NetworkDevice;
+import com.btisystems.pronx.ems.core.snmp.ISnmpSession;
+import java.io.IOException;
+import java.util.Arrays;
+import org.onosproject.net.device.DefaultDeviceDescription;
+import org.onosproject.net.device.DeviceDescription;
+import org.slf4j.Logger;
+import static org.slf4j.LoggerFactory.getLogger;
+import org.snmp4j.smi.OID;
+
+/**
+ * A vendor-specific implementation supporting BTI Systems BTI-7000 equipment.
+ */
+public class Bti7000DeviceDescriptionProvider implements SnmpDeviceDescriptionProvider {
+    private final Logger log = getLogger(getClass());
+    protected static final IClassRegistry CLASS_REGISTRY =
+            new ClassRegistry(_OidRegistry.oidRegistry, I_Device.class);
+    private static final String UNKNOWN = "unknown";
+
+    @Override
+    public DeviceDescription populateDescription(ISnmpSession session, DeviceDescription description) {
+        NetworkDevice networkDevice = new NetworkDevice(CLASS_REGISTRY,
+                session.getAddress().getHostAddress());
+        try {
+            session.walkDevice(networkDevice, Arrays.asList(new OID[]{
+                CLASS_REGISTRY.getClassToOidMap().get(
+                com.btisystems.mibbler.mibs.bti7000.bti7000_13_2_0.mib_2.System.class)}));
+
+            com.btisystems.mibbler.mibs.bti7000.bti7000_13_2_0.mib_2.System systemTree =
+                    (com.btisystems.mibbler.mibs.bti7000.bti7000_13_2_0.mib_2.System)
+                    networkDevice.getRootObject().getEntity(CLASS_REGISTRY.getClassToOidMap().get(
+                                    com.btisystems.mibbler.mibs.bti7000.bti7000_13_2_0.mib_2.System.class));
+            if (systemTree != null) {
+                String[] systemComponents = systemTree.getSysDescr().split(";");
+                return new DefaultDeviceDescription(description.deviceUri(), description.type(),
+                        systemComponents[0], systemComponents[2], systemComponents[3],
+                        UNKNOWN, description.chassisId());
+            }
+        } catch (IOException ex) {
+            log.error("Error reading details for device {}.", session.getAddress(), ex);
+        }
+        return description;
+    }
+
+}
diff --git a/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/DeviceState.java b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/DeviceState.java
new file mode 100644
index 0000000..e358927
--- /dev/null
+++ b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/DeviceState.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2015 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.snmp.device.impl;
+    /**
+     * The Device State is used to determine whether the device is active or inactive. This state information will help
+     * Device Creator to add or delete the device from the core.
+     */
+    public  enum DeviceState {
+        /* Used to specify Active state of the device */
+
+        ACTIVE,
+        /* Used to specify inactive state of the device */
+        INACTIVE,
+        /* Used to specify invalid state of the device */
+        INVALID
+    }
diff --git a/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/NetSnmpDeviceDescriptionProvider.java b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/NetSnmpDeviceDescriptionProvider.java
new file mode 100644
index 0000000..5e6689a
--- /dev/null
+++ b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/NetSnmpDeviceDescriptionProvider.java
@@ -0,0 +1,66 @@
+/*
+ * 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.snmp.device.impl;
+
+import com.btisystems.mibbler.mibs.netsnmp.netsnmp.I_Device;
+import com.btisystems.mibbler.mibs.netsnmp.netsnmp._OidRegistry;
+import com.btisystems.pronx.ems.core.model.ClassRegistry;
+import com.btisystems.pronx.ems.core.model.IClassRegistry;
+import com.btisystems.pronx.ems.core.model.NetworkDevice;
+import com.btisystems.pronx.ems.core.snmp.ISnmpSession;
+import java.io.IOException;
+import java.util.Arrays;
+import org.apache.commons.lang.StringUtils;
+import org.onosproject.net.device.DefaultDeviceDescription;
+import org.onosproject.net.device.DeviceDescription;
+import org.slf4j.Logger;
+import static org.slf4j.LoggerFactory.getLogger;
+import org.snmp4j.smi.OID;
+
+/**
+ * A agent-specific implementation supporting NET-SNMP agents.
+ */
+public class NetSnmpDeviceDescriptionProvider implements SnmpDeviceDescriptionProvider {
+    private final Logger log = getLogger(getClass());
+    protected static final IClassRegistry CLASS_REGISTRY =
+            new ClassRegistry(_OidRegistry.oidRegistry, I_Device.class);
+    private static final String UNKNOWN = "unknown";
+
+    @Override
+    public DeviceDescription populateDescription(ISnmpSession session, DeviceDescription description) {
+        NetworkDevice networkDevice = new NetworkDevice(CLASS_REGISTRY,
+                session.getAddress().getHostAddress());
+        try {
+            session.walkDevice(networkDevice, Arrays.asList(new OID[]{
+                CLASS_REGISTRY.getClassToOidMap().get(
+                com.btisystems.mibbler.mibs.netsnmp.netsnmp.mib_2.System.class)}));
+
+            com.btisystems.mibbler.mibs.netsnmp.netsnmp.mib_2.System systemTree =
+                    (com.btisystems.mibbler.mibs.netsnmp.netsnmp.mib_2.System)
+                    networkDevice.getRootObject().getEntity(CLASS_REGISTRY.getClassToOidMap().get(
+                                    com.btisystems.mibbler.mibs.netsnmp.netsnmp.mib_2.System.class));
+            if (systemTree != null) {
+                // TODO SNMP sys-contacts may be verbose; ONOS-GUI doesn't abbreviate fields neatly;
+                // so cut it here until supported in prop displayer
+                String manufacturer = StringUtils.abbreviate(systemTree.getSysContact(), 20);
+                return new DefaultDeviceDescription(description.deviceUri(), description.type(), manufacturer,
+                        UNKNOWN, UNKNOWN, UNKNOWN, description.chassisId());
+            }
+        } catch (IOException ex) {
+            log.error("Error reading details for device {}.", session.getAddress(), ex);
+        }
+        return description;
+    }
+
+}
diff --git a/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDevice.java b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDevice.java
new file mode 100644
index 0000000..8b385dc
--- /dev/null
+++ b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDevice.java
@@ -0,0 +1,134 @@
+/*
+ * Copyright 2015 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.snmp.device.impl;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.slf4j.LoggerFactory.getLogger;
+
+
+import org.slf4j.Logger;
+
+/**
+ * This is a logical representation of actual SNMP device, carrying all the necessary information to connect and execute
+ * SNMP operations.
+ */
+public class SnmpDevice {
+
+    private final Logger log = getLogger(SnmpDevice.class);
+
+
+    private static final int DEFAULT_SNMP_PORT = 161;
+
+    private final String snmpHost;
+    private int snmpPort = DEFAULT_SNMP_PORT;
+    private final String community;
+    private boolean reachable = false;
+
+    private DeviceState deviceState = DeviceState.INVALID;
+
+    protected SnmpDevice(String snmpHost, int snmpPort, String community) {
+
+        this.snmpHost = checkNotNull(snmpHost, "SNMP Device IP cannot be null");
+        this.snmpPort = checkNotNull(snmpPort, "SNMP Device snmp port cannot be null");
+        this.community = community;
+    }
+
+    /**
+     * This will try to connect to SNMP device.
+     *
+     */
+    public void init() {
+
+        reachable = true;
+    }
+
+    /**
+     * This would return host IP and host Port, used by this particular SNMP Device.
+     *
+     * @return Device Information.
+     */
+    public String deviceInfo() {
+        return new StringBuilder("host: ").append(snmpHost).append(". port: ")
+                .append(snmpPort).toString();
+    }
+
+    /**
+     * This will terminate the device connection.
+     */
+    public void disconnect() {
+        log.info("disconnect");
+        reachable = false;
+    }
+
+    /**
+     * This api is intended to know whether the device is connected or not.
+     *
+     * @return true if connected
+     */
+    public boolean isReachable() {
+        return reachable;
+    }
+
+    /**
+     * This will return the IP used connect ssh on the device.
+     *
+     * @return SNMP Device IP
+     */
+    public String getSnmpHost() {
+        return snmpHost;
+    }
+
+    /**
+     * This will return the SSH Port used connect the device.
+     *
+     * @return SSH Port number
+     */
+    public int getSnmpPort() {
+        return snmpPort;
+    }
+
+    public String getCommunity() {
+        return community;
+    }
+
+    /**
+     * Retrieve current state of the device.
+     *
+     * @return Current Device State
+     */
+    public DeviceState getDeviceState() {
+        return deviceState;
+    }
+
+    /**
+     * This is set the state information for the device.
+     *
+     * @param deviceState Next Device State
+     */
+    public void setDeviceState(DeviceState deviceState) {
+        this.deviceState = deviceState;
+    }
+
+    /**
+     * Check whether the device is in Active state.
+     *
+     * @return true if the device is Active
+     */
+    public boolean isActive() {
+        return deviceState == DeviceState.ACTIVE;
+    }
+
+}
diff --git a/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceDescriptionProvider.java b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceDescriptionProvider.java
new file mode 100644
index 0000000..4be3a35
--- /dev/null
+++ b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceDescriptionProvider.java
@@ -0,0 +1,33 @@
+/*
+ * 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.snmp.device.impl;
+
+import com.btisystems.pronx.ems.core.snmp.ISnmpSession;
+import org.onosproject.net.device.DeviceDescription;
+
+/**
+ * Abstraction of an entity which updates a device description with information retrieved via SNMP.
+ */
+public interface SnmpDeviceDescriptionProvider {
+
+    /**
+     * Generated an updated device description.
+     *
+     * @param session SNMP session
+     * @param description old device description
+     * @return new updated description
+     */
+    DeviceDescription populateDescription(ISnmpSession session, DeviceDescription description);
+
+}
diff --git a/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceProvider.java b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceProvider.java
new file mode 100644
index 0000000..f18ae72
--- /dev/null
+++ b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceProvider.java
@@ -0,0 +1,406 @@
+/*
+ * Copyright 2015 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.snmp.device.impl;
+
+import com.btisystems.pronx.ems.core.snmp.DefaultSnmpConfigurationFactory;
+import com.btisystems.pronx.ems.core.snmp.ISnmpConfiguration;
+import com.btisystems.pronx.ems.core.snmp.ISnmpConfigurationFactory;
+import com.btisystems.pronx.ems.core.snmp.ISnmpSession;
+import com.btisystems.pronx.ems.core.snmp.ISnmpSessionFactory;
+import com.btisystems.pronx.ems.core.snmp.SnmpSessionFactory;
+import com.btisystems.pronx.ems.core.snmp.V2cSnmpConfiguration;
+import static com.google.common.base.Strings.isNullOrEmpty;
+import java.io.IOException;
+import static org.onlab.util.Tools.delay;
+import static org.onlab.util.Tools.get;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.Dictionary;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+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.onlab.packet.ChassisId;
+import org.onosproject.cfg.ComponentConfigService;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.MastershipRole;
+import org.onosproject.net.device.DefaultDeviceDescription;
+import org.onosproject.net.device.DeviceDescription;
+import org.onosproject.net.device.DeviceProvider;
+import org.onosproject.net.device.DeviceProviderRegistry;
+import org.onosproject.net.device.DeviceProviderService;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.provider.AbstractProvider;
+import org.onosproject.net.provider.ProviderId;
+import org.osgi.service.component.ComponentContext;
+import org.slf4j.Logger;
+
+/**
+ * Provider which will try to fetch the details of SNMP devices from the core and run a capability discovery on each of
+ * the device.
+ */
+@Component(immediate = true)
+public class SnmpDeviceProvider extends AbstractProvider
+        implements DeviceProvider {
+
+    private final Logger log = getLogger(SnmpDeviceProvider.class);
+
+    private static final String UNKNOWN = "unknown";
+
+    protected Map<DeviceId, SnmpDevice> snmpDeviceMap = new ConcurrentHashMap<>();
+
+    private DeviceProviderService providerService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceProviderRegistry providerRegistry;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ComponentConfigService cfgService;
+
+    private final ExecutorService deviceBuilder = Executors
+            .newFixedThreadPool(1, groupedThreads("onos/snmp", "device-creator"));
+
+    // Delay between events in ms.
+    private static final int EVENTINTERVAL = 5;
+
+    private static final String SCHEME = "snmp";
+
+    @Property(name = "devConfigs", value = "", label = "Instance-specific configurations")
+    private String devConfigs = null;
+
+    @Property(name = "devPasswords", value = "", label = "Instance-specific password")
+    private String devPasswords = null;
+
+    //TODO Could be replaced with a service lookup, and bundles per device variant.
+    Map<String, SnmpDeviceDescriptionProvider> providers = new HashMap<>();
+
+    private final ISnmpSessionFactory sessionFactory;
+
+    /**
+     * Creates a provider with the supplier identifier.
+     */
+    public SnmpDeviceProvider() {
+        super(new ProviderId("snmp", "org.onosproject.provider.device"));
+        sessionFactory = new SnmpSessionFactory(
+                new DefaultSnmpConfigurationFactory(new V2cSnmpConfiguration()));
+        providers.put("1.3.6.1.4.1.18070.2.2", new Bti7000DeviceDescriptionProvider());
+        providers.put("1.3.6.1.4.1.20408", new NetSnmpDeviceDescriptionProvider());
+    }
+
+    @Activate
+    public void activate(ComponentContext context) {
+        log.info("activating for snmp devices ...");
+        cfgService.registerProperties(getClass());
+        providerService = providerRegistry.register(this);
+        modified(context);
+        log.info("activated ok");
+    }
+
+    @Deactivate
+    public void deactivate(ComponentContext context) {
+
+        log.info("deactivating for snmp devices ...");
+
+        cfgService.unregisterProperties(getClass(), false);
+        try {
+            snmpDeviceMap
+                    .entrySet().stream().forEach((deviceEntry) -> {
+                        deviceBuilder.submit(new DeviceCreator(deviceEntry.getValue(), false));
+                    });
+            deviceBuilder.awaitTermination(1000, TimeUnit.MILLISECONDS);
+        } catch (InterruptedException e) {
+            log.error("Device builder did not terminate");
+        }
+        deviceBuilder.shutdownNow();
+        snmpDeviceMap.clear();
+        providerRegistry.unregister(this);
+        providerService = null;
+        log.info("Stopped");
+    }
+
+    @Modified
+    public void modified(ComponentContext context) {
+        log.info("modified ...");
+
+        if (context == null) {
+            log.info("No configuration file");
+            return;
+        }
+        Dictionary<?, ?> properties = context.getProperties();
+
+        log.info("properties={}", context.getProperties());
+
+        String deviceCfgValue = get(properties, "devConfigs");
+        log.info("Settings: devConfigs={}", deviceCfgValue);
+        if (!isNullOrEmpty(deviceCfgValue)) {
+            addOrRemoveDevicesConfig(deviceCfgValue);
+        }
+        log.info("... modified");
+
+    }
+
+    private void addOrRemoveDevicesConfig(String deviceConfig) {
+        for (String deviceEntry : deviceConfig.split(",")) {
+            SnmpDevice device = processDeviceEntry(deviceEntry);
+            if (device != null) {
+                log.info("Device Detail:host={}, port={}, state={}",
+                        new Object[]{device.getSnmpHost(),
+                            device.getSnmpPort(),
+                            device.getDeviceState().name()}
+                );
+                if (device.isActive()) {
+                    deviceBuilder.submit(new DeviceCreator(device, true));
+                } else {
+                    deviceBuilder.submit(new DeviceCreator(device, false));
+                }
+            }
+        }
+    }
+
+    private SnmpDevice processDeviceEntry(String deviceEntry) {
+        if (deviceEntry == null) {
+            log.info("No content for Device Entry, so cannot proceed further.");
+            return null;
+        }
+        log.info("Trying to convert {} to a SNMP Device Object", deviceEntry);
+        SnmpDevice device = null;
+        try {
+            String userInfo = deviceEntry.substring(0, deviceEntry
+                    .lastIndexOf('@'));
+            String hostInfo = deviceEntry.substring(deviceEntry
+                    .lastIndexOf('@') + 1);
+            String[] infoSplit = userInfo.split(":");
+            String username = infoSplit[0];
+            String password = infoSplit[1];
+            infoSplit = hostInfo.split(":");
+            String hostIp = infoSplit[0];
+            Integer hostPort;
+            try {
+                hostPort = Integer.parseInt(infoSplit[1]);
+            } catch (NumberFormatException nfe) {
+                log.error("Bad Configuration Data: Failed to parse host port number string: "
+                        + infoSplit[1]);
+                throw nfe;
+            }
+            String deviceState = infoSplit[2];
+            if (isNullOrEmpty(username) || isNullOrEmpty(password)
+                    || isNullOrEmpty(hostIp) || hostPort == 0) {
+                log.warn("Bad Configuration Data: both user and device information parts of Configuration "
+                        + deviceEntry + " should be non-nullable");
+            } else {
+                device = new SnmpDevice(hostIp, hostPort, password);
+                if (!isNullOrEmpty(deviceState)) {
+                    if (deviceState.toUpperCase().equals(DeviceState.ACTIVE.name())) {
+                        device.setDeviceState(DeviceState.ACTIVE);
+                    } else if (deviceState.toUpperCase()
+                            .equals(DeviceState.INACTIVE.name())) {
+                        device.setDeviceState(DeviceState.INACTIVE);
+                    } else {
+                        log.warn("Device State Information can not be empty, so marking the state as INVALID");
+                        device.setDeviceState(DeviceState.INVALID);
+                    }
+                } else {
+                    log.warn("The device entry do not specify state information, so marking the state as INVALID");
+                    device.setDeviceState(DeviceState.INVALID);
+                }
+            }
+        } catch (ArrayIndexOutOfBoundsException aie) {
+            log.error("Error while reading config infromation from the config file: "
+                    + "The user, host and device state infomation should be "
+                    + "in the order 'userInfo@hostInfo:deviceState'"
+                    + deviceEntry, aie);
+        } catch (Exception e) {
+            log.error("Error while parsing config information for the device entry: "
+                    + deviceEntry, e);
+        }
+        return device;
+    }
+
+    @Override
+    public void triggerProbe(DeviceId deviceId) {
+        // TODO SNMP devices should be polled at scheduled intervals to retrieve their
+        // reachability status and other details e.g.swVersion, serialNumber,chassis,
+    }
+
+    @Override
+    public void roleChanged(DeviceId deviceId, MastershipRole newRole) {
+
+    }
+
+    @Override
+    public boolean isReachable(DeviceId deviceId) {
+        SnmpDevice snmpDevice = snmpDeviceMap.get(deviceId);
+        if (snmpDevice == null) {
+            log.warn("BAD REQUEST: the requested device id: "
+                    + deviceId.toString()
+                    + "  is not associated to any SNMP Device");
+            return false;
+        }
+        return snmpDevice.isReachable();
+    }
+
+    /**
+     * This class is intended to add or remove Configured SNMP Devices. Functionality relies on 'createFlag' and
+     * 'SnmpDevice' content. The functionality runs as a thread and depending on the 'createFlag' value it will create
+     * or remove Device entry from the core.
+     */
+    private class DeviceCreator implements Runnable {
+
+        private SnmpDevice device;
+        private boolean createFlag;
+
+        public DeviceCreator(SnmpDevice device, boolean createFlag) {
+            this.device = device;
+            this.createFlag = createFlag;
+        }
+
+        @Override
+        public void run() {
+            if (createFlag) {
+                log.info("Trying to create Device Info on ONOS core");
+                advertiseDevices();
+            } else {
+                log.info("Trying to remove Device Info on ONOS core");
+                removeDevices();
+            }
+        }
+
+        /**
+         * For each SNMP Device, remove the entry from the device store.
+         */
+        private void removeDevices() {
+            if (device == null) {
+                log.warn("The Request SNMP Device is null, cannot proceed further");
+                return;
+            }
+            try {
+                DeviceId did = getDeviceId();
+                if (!snmpDeviceMap.containsKey(did)) {
+                    log.error("BAD Request: 'Currently device is not discovered, "
+                            + "so cannot remove/disconnect the device: "
+                            + device.deviceInfo() + "'");
+                    return;
+                }
+                providerService.deviceDisconnected(did);
+                device.disconnect();
+                snmpDeviceMap.remove(did);
+                delay(EVENTINTERVAL);
+            } catch (URISyntaxException uriSyntaxExcpetion) {
+                log.error("Syntax Error while creating URI for the device: "
+                        + device.deviceInfo()
+                        + " couldn't remove the device from the store",
+                        uriSyntaxExcpetion);
+            }
+        }
+
+        /**
+         * Initialize SNMP Device object, and notify core saying device connected.
+         */
+        private void advertiseDevices() {
+            try {
+                if (device == null) {
+                    log.warn("The Request SNMP Device is null, cannot proceed further");
+                    return;
+                }
+                device.init();
+                DeviceId did = getDeviceId();
+                ChassisId cid = new ChassisId();
+
+
+                DeviceDescription desc = new DefaultDeviceDescription(
+                        did.uri(), Device.Type.OTHER, UNKNOWN, UNKNOWN, UNKNOWN, UNKNOWN, cid);
+
+                desc = populateDescriptionFromDevice(did, desc);
+
+                log.info("Persisting Device " + did.uri().toString());
+
+                snmpDeviceMap.put(did, device);
+                providerService.deviceConnected(did, desc);
+                log.info("Done with Device Info Creation on ONOS core. Device Info: "
+                        + device.deviceInfo() + " " + did.uri().toString());
+                delay(EVENTINTERVAL);
+            } catch (URISyntaxException e) {
+                log.error("Syntax Error while creating URI for the device: "
+                        + device.deviceInfo()
+                        + " couldn't persist the device onto the store", e);
+            } catch (Exception e) {
+                log.error("Error while initializing session for the device: "
+                        + (device != null ? device.deviceInfo() : null), e);
+            }
+        }
+
+        private DeviceDescription populateDescriptionFromDevice(DeviceId did, DeviceDescription desc) {
+            String[] deviceComponents = did.toString().split(":");
+            if (deviceComponents.length > 1) {
+                String ipAddress = deviceComponents[1];
+                String port = deviceComponents[2];
+
+           ISnmpConfiguration config = new V2cSnmpConfiguration();
+            config.setPort(Integer.parseInt(port));
+
+                try (ISnmpSession session = sessionFactory.createSession(config, ipAddress)) {
+                    // Each session will be auto-closed.
+                    String deviceOID = session.identifyDevice();
+
+                    if (providers.containsKey(deviceOID)) {
+                        desc = providers.get(deviceOID).populateDescription(session, desc);
+                    }
+
+                } catch (IOException | RuntimeException ex) {
+                    log.error("Failed to walk device.", ex.getMessage());
+                    log.debug("Detailed problem was ", ex);
+                }
+            }
+            return desc;
+        }
+
+        /**
+         * This will build a device id for the device.
+         */
+        private DeviceId getDeviceId() throws URISyntaxException {
+            String additionalSSP = new StringBuilder(
+                    device.getSnmpHost()).append(":")
+                    .append(device.getSnmpPort()).toString();
+            return DeviceId.deviceId(new URI(SCHEME, additionalSSP,
+                    null));
+        }
+    }
+
+    protected ISnmpSessionFactory getSessionFactory(ISnmpConfigurationFactory configurationFactory) {
+        return new SnmpSessionFactory(configurationFactory);
+    }
+}
diff --git a/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/package-info.java b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/package-info.java
new file mode 100644
index 0000000..5c888f5
--- /dev/null
+++ b/providers/snmp/device/src/main/java/org/onosproject/provider/snmp/device/impl/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2015 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 SNMP capability request as a means of infrastructure device discovery.
+ */
+package org.onosproject.provider.snmp.device.impl;
\ No newline at end of file