HONEYCOMB-23 Add plugin sample and sample minimal distribution

Change-Id: Idbcdc5a52a9bfd3b90c039f1a1e58c258cd01849
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

10 files changed, 693 insertions, 0 deletions

diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/LowerLayerAccess.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/LowerLayerAccess.java
new file mode 100644
index 000000000..4b815bf35
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/LowerLayerAccess.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping;
+
+import com.google.common.collect.Lists;
+import com.google.inject.Inject;
+import io.fd.honeycomb.samples.interfaces.mapping.cfgattrs.InterfacesPluginConfiguration;
+import io.fd.honeycomb.translate.write.WriteContext;
+import java.util.ArrayList;
+import javax.annotation.Nonnull;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.Interface;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is a sample class representing common resource for readers and writers to access the lower layer
+ */
+public final class LowerLayerAccess {
+
+    private static final Logger LOG = LoggerFactory.getLogger(LowerLayerAccess.class);
+
+    @Inject
+    public LowerLayerAccess(@Nonnull final InterfacesPluginConfiguration configuration) {
+        LOG.info("Creating lower layer access with configuration: {}", configuration);
+    }
+
+    public void writeInterface(final InstanceIdentifier<Interface> id, final Interface dataAfter,
+                               final WriteContext writeContext) {
+        LOG.info("Writing interface: {}. to {}", dataAfter, id);
+        // This is where actual write/propagation happens
+        dataAfter.getMtu();
+    }
+
+    public void deleteInterface(final InstanceIdentifier<Interface> id, final Interface dataBefore,
+                                final WriteContext writeContext) {
+        LOG.info("Deleting interface: {}. to {}", dataBefore, id);
+        final String ifcToBeDeleted = id.firstKeyOf(Interface.class).getInterfaceId().getValue();
+        // This is where actual write/propagation happens
+    }
+
+    public long getTotalPacketsForInterface(final String ifcName) {
+        return 500L;
+    }
+
+    public long getDroppedPacketsForIfc(final String ifcName) {
+        return 50L;
+    }
+
+    public ArrayList<String> getAllInterfaceNames() {
+        return Lists.newArrayList("ifc1", "ifc2");
+    }
+
+    public int getMtuForInterface(final String ifcName) {
+        return 66;
+    }
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/SampleInterfaceModule.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/SampleInterfaceModule.java
new file mode 100644
index 000000000..000113f11
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/SampleInterfaceModule.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping;
+
+import com.google.inject.AbstractModule;
+import com.google.inject.Singleton;
+import com.google.inject.multibindings.Multibinder;
+import io.fd.honeycomb.data.init.DataTreeInitializer;
+import io.fd.honeycomb.notification.ManagedNotificationProducer;
+import io.fd.honeycomb.samples.interfaces.mapping.config.InterfacesWriterFactory;
+import io.fd.honeycomb.samples.interfaces.mapping.oper.InterfacesReaderFactory;
+import io.fd.honeycomb.samples.interfaces.mapping.cfgattrs.InterfacesPluginConfiguration;
+import io.fd.honeycomb.samples.interfaces.mapping.init.InterfacesInitializer;
+import io.fd.honeycomb.samples.interfaces.mapping.notification.InterfaceUpNotificationProducer;
+import io.fd.honeycomb.translate.read.ReaderFactory;
+import io.fd.honeycomb.translate.write.WriterFactory;
+import net.jmob.guice.conf.core.ConfigurationModule;
+
+/**
+ * This is some glue code necessary for Honeycomb distribution to pick up the plugin classes
+ */
+public final class SampleInterfaceModule extends AbstractModule {
+
+    @Override
+    protected void configure() {
+        // These are plugin specific config attributes
+        install(ConfigurationModule.create());
+        requestInjection(InterfacesPluginConfiguration.class);
+
+        // These are plugin's internal components
+        bind(LowerLayerAccess.class).in(Singleton.class);
+
+        // Below are classes picked up by HC framework
+        Multibinder.newSetBinder(binder(), WriterFactory.class).addBinding().to(InterfacesWriterFactory.class);
+        Multibinder.newSetBinder(binder(), ReaderFactory.class).addBinding().to(InterfacesReaderFactory.class);
+        Multibinder.newSetBinder(binder(), DataTreeInitializer.class).addBinding().to(InterfacesInitializer.class);
+        Multibinder.newSetBinder(binder(), ManagedNotificationProducer.class).addBinding()
+                .to(InterfaceUpNotificationProducer.class);
+    }
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/cfgattrs/InterfacesPluginConfiguration.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/cfgattrs/InterfacesPluginConfiguration.java
new file mode 100644
index 000000000..881c18aa0
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/cfgattrs/InterfacesPluginConfiguration.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.cfgattrs;
+
+import net.jmob.guice.conf.core.BindConfig;
+import net.jmob.guice.conf.core.InjectConfig;
+import net.jmob.guice.conf.core.Syntax;
+
+@BindConfig(value = "sample-interfaces", syntax = Syntax.JSON)
+public class InterfacesPluginConfiguration {
+
+    @InjectConfig("some-config-attribute")
+    String someConfigAttribute;
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/config/InterfaceWriterCustomizer.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/config/InterfaceWriterCustomizer.java
new file mode 100644
index 000000000..af185d8b0
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/config/InterfaceWriterCustomizer.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.config;
+
+import io.fd.honeycomb.samples.interfaces.mapping.LowerLayerAccess;
+import io.fd.honeycomb.translate.spi.write.ListWriterCustomizer;
+import io.fd.honeycomb.translate.write.WriteContext;
+import io.fd.honeycomb.translate.write.WriteFailedException;
+import javax.annotation.Nonnull;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.Interface;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.InterfaceKey;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is a customizer responsible for writing(updating and also deleting) Interface config data
+ */
+public class InterfaceWriterCustomizer implements ListWriterCustomizer<Interface, InterfaceKey> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(InterfaceWriterCustomizer.class);
+
+    private final LowerLayerAccess access;
+
+    public InterfaceWriterCustomizer(final LowerLayerAccess access) {
+        this.access = access;
+    }
+
+    @Override
+    public void writeCurrentAttributes(@Nonnull final InstanceIdentifier<Interface> id,
+                                       @Nonnull final Interface dataAfter, @Nonnull final WriteContext writeContext)
+            throws WriteFailedException {
+        try {
+            // Context can be used just like the context in ReadCustomizer see InterfaceReaderCustomizer
+            // + it also provides a window into the entire configuration tree before current transaction and during current transaction
+            // just in case, some additional data is necessary here
+            access.writeInterface(id, dataAfter, writeContext);
+        } catch (Exception e) {
+            throw new WriteFailedException.CreateFailedException(id, dataAfter, e);
+        }
+    }
+
+    @Override
+    public void updateCurrentAttributes(@Nonnull final InstanceIdentifier<Interface> id,
+                                        @Nonnull final Interface dataBefore, @Nonnull final Interface dataAfter,
+                                        @Nonnull final WriteContext writeContext) throws WriteFailedException {
+        // There are cases when lower layer does not support all of the CRUD operations, in which case, the handler
+        // should look like this (This will reject configuration from upper layers, returning error/rpc-error):
+        throw new WriteFailedException.UpdateFailedException(id, dataBefore, dataAfter,
+                new UnsupportedOperationException("Unable to update interface data, unsupported at lower layer"));
+    }
+
+    @Override
+    public void deleteCurrentAttributes(@Nonnull final InstanceIdentifier<Interface> id,
+                                        @Nonnull final Interface dataBefore, @Nonnull final WriteContext writeContext)
+            throws WriteFailedException {
+        try {
+            // Context can be used just like the context in ReadCustomizer see InterfaceReaderCustomizer
+            // + it also provides a window into the entire configuration tree before current transaction and during current transaction
+            // just in case, some additional data is necessary here
+            access.deleteInterface(id, dataBefore, writeContext);
+        } catch (Exception e) {
+            throw new WriteFailedException.DeleteFailedException(id, e);
+        }
+    }
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/config/InterfacesWriterFactory.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/config/InterfacesWriterFactory.java
new file mode 100644
index 000000000..d3b22c345
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/config/InterfacesWriterFactory.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.config;
+
+import com.google.inject.Inject;
+import io.fd.honeycomb.samples.interfaces.mapping.LowerLayerAccess;
+import io.fd.honeycomb.translate.impl.write.GenericListWriter;
+import io.fd.honeycomb.translate.write.WriterFactory;
+import io.fd.honeycomb.translate.write.registry.ModifiableWriterRegistryBuilder;
+import javax.annotation.Nonnull;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.Interfaces;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.Interface;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class InterfacesWriterFactory implements WriterFactory {
+
+    @Nonnull
+    private final LowerLayerAccess access;
+
+    @Inject
+    public InterfacesWriterFactory(@Nonnull final LowerLayerAccess access) {
+        this.access = access;
+    }
+
+    @Override
+    public void init(@Nonnull final ModifiableWriterRegistryBuilder registry) {
+        // ReaderFactory is intended for registering Writers into HC framework
+        // Writers handle ONLY config (config "true") data coming from upper layers and propagate them into lower layer/device
+        // they are triggered when RESTCONF PUT/POST on config is invoked or when NETCONF edit-config + commit operation is executed
+
+        // Our model root for operational data is Interfaces
+        final InstanceIdentifier<Interfaces> root = InstanceIdentifier.create(Interfaces.class);
+        // But unlike ReaderFactories, there's no need to create a structural writer, we can "ignore" any nodes
+        // that do not contain actual data (leaves)
+
+        // Next child node is Interface (list)
+        final InstanceIdentifier<Interface> ifcListId = root.child(Interface.class);
+        registry.add(new GenericListWriter<>(ifcListId, new InterfaceWriterCustomizer(access)));
+    }
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/init/InterfacesInitializer.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/init/InterfacesInitializer.java
new file mode 100644
index 000000000..9aea508c7
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/init/InterfacesInitializer.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.init;
+
+import com.google.inject.Inject;
+import com.google.inject.name.Named;
+import io.fd.honeycomb.data.init.AbstractDataTreeConverter;
+import java.util.stream.Collectors;
+import org.opendaylight.controller.md.sal.binding.api.DataBroker;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.Interfaces;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfacesBuilder;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfacesState;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.InterfaceBuilder;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is an initializer for interfaces plugin. Its main goal is to revers-engineer configuration data (config "true")
+ * for interfaces model from operational data. In this case, we are trying to recreate Interfaces container from InterfacesState
+ * container. Thanks to symmetrical nature of the model, it's pretty straightforward.
+ *
+ * This is very useful when the lower layer already contains some data that should be revers-engineer to config data
+ * in honeycomb in order to get HC and lower layer to sync... It makes life of upper layers much easier
+ *
+ * However it's not always possible to perform this task so the initializers are optional for plugins
+ */
+public class InterfacesInitializer extends AbstractDataTreeConverter<InterfacesState, Interfaces> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(InterfacesInitializer.class);
+
+    @Inject
+    public InterfacesInitializer(@Named("honeycomb-initializer") final DataBroker bindingDataBroker) {
+        super(bindingDataBroker,
+                InstanceIdentifier.create(InterfacesState.class), InstanceIdentifier.create(Interfaces.class));
+    }
+
+    @Override
+    protected Interfaces convert(final InterfacesState operationalData) {
+        // Just convert operational data into config data
+        // The operational data are queried from lower layer using readerCustomizers from this plugin
+
+        LOG.info("Initializing interfaces config data from: {}", operationalData);
+
+        return new InterfacesBuilder()
+                .setInterface(operationalData.getInterface().stream()
+                        .map(oper -> new InterfaceBuilder()
+                                .setMtu(oper.getMtu())
+                                .setInterfaceId(oper.getInterfaceId())
+                                .build())
+                        .collect(Collectors.toList()))
+                .build();
+    }
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/notification/InterfaceUpNotificationProducer.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/notification/InterfaceUpNotificationProducer.java
new file mode 100644
index 000000000..76d2c5dc8
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/notification/InterfaceUpNotificationProducer.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.notification;
+
+import com.google.inject.Inject;
+import io.fd.honeycomb.notification.ManagedNotificationProducer;
+import io.fd.honeycomb.notification.NotificationCollector;
+import io.fd.honeycomb.samples.interfaces.mapping.LowerLayerAccess;
+import java.util.Collection;
+import java.util.Collections;
+import javax.annotation.Nonnull;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfaceId;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfaceUp;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfaceUpBuilder;
+import org.opendaylight.yangtools.yang.binding.Notification;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Notification producer for sample interfaces plugin
+ */
+public class InterfaceUpNotificationProducer implements ManagedNotificationProducer {
+
+    private static final Logger LOG = LoggerFactory.getLogger(InterfaceUpNotificationProducer.class);
+
+    @Nonnull
+    private final LowerLayerAccess access;
+
+    private Thread thread;
+
+    @Inject
+    public InterfaceUpNotificationProducer(@Nonnull final LowerLayerAccess access) {
+        this.access = access;
+    }
+
+    @Override
+    public void start(@Nonnull final NotificationCollector collector) {
+        LOG.info("Starting notification stream for interfaces");
+
+        // Simulating notification producer
+        thread = new Thread(() -> {
+            while(true) {
+                if (Thread.currentThread().isInterrupted()) {
+                    return;
+                }
+
+                try {
+                    Thread.sleep(2000);
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    break;
+                }
+
+
+                final InterfaceUp ifc1 = new InterfaceUpBuilder().setInterfaceId(new InterfaceId("ifc1")).build();
+                LOG.info("Emitting notification: {}", ifc1);
+                collector.onNotification(ifc1);
+            }
+        }, "NotificationProducer");
+        thread.setDaemon(true);
+        thread.start();
+    }
+
+    @Override
+    public void stop() {
+        if(thread != null) {
+            thread.interrupt();
+        }
+    }
+
+    @Nonnull
+    @Override
+    public Collection<Class<? extends Notification>> getNotificationTypes() {
+        // Producing only this single type of notification
+        return Collections.singleton(InterfaceUp.class);
+    }
+
+    @Override
+    public void close() throws Exception {
+        stop();
+    }
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/CountersReaderCustomizer.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/CountersReaderCustomizer.java
new file mode 100644
index 000000000..b5ec2cbd9
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/CountersReaderCustomizer.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.oper;
+
+import io.fd.honeycomb.samples.interfaces.mapping.LowerLayerAccess;
+import io.fd.honeycomb.translate.read.ReadContext;
+import io.fd.honeycomb.translate.read.ReadFailedException;
+import io.fd.honeycomb.translate.spi.read.ReaderCustomizer;
+import javax.annotation.Nonnull;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810._interface.state.Counters;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810._interface.state.CountersBuilder;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.state.Interface;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.state.InterfaceBuilder;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.state.InterfaceKey;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is a customizer responsible for reading Counters operational data
+ */
+public class CountersReaderCustomizer implements ReaderCustomizer<Counters, CountersBuilder> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(CountersReaderCustomizer.class);
+    private final LowerLayerAccess access;
+
+    public CountersReaderCustomizer(final LowerLayerAccess access) {
+        this.access = access;
+    }
+
+
+    @Nonnull
+    @Override
+    public CountersBuilder getBuilder(@Nonnull final InstanceIdentifier<Counters> id) {
+        return new CountersBuilder();
+    }
+
+    @Override
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<Counters> id,
+                                      @Nonnull final CountersBuilder builder, @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        // Get the information about which interface to get counters for
+        final InterfaceKey interfaceKey = id.firstKeyOf(Interface.class);
+        LOG.info("Reading counters for interface: {} at {}", interfaceKey.getInterfaceId(), id);
+
+        // Set some random data
+        builder.setDroppedPackets(access.getDroppedPacketsForIfc(interfaceKey.getInterfaceId().getValue()));
+        builder.setTotalPackets(access.getTotalPacketsForInterface(interfaceKey.getInterfaceId().getValue()));
+    }
+
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final Counters readValue) {
+        ((InterfaceBuilder) parentBuilder).setCounters(readValue);
+    }
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/InterfaceReaderCustomizer.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/InterfaceReaderCustomizer.java
new file mode 100644
index 000000000..7b69005e0
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/InterfaceReaderCustomizer.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.oper;
+
+import io.fd.honeycomb.samples.interfaces.mapping.LowerLayerAccess;
+import io.fd.honeycomb.translate.read.ReadContext;
+import io.fd.honeycomb.translate.read.ReadFailedException;
+import io.fd.honeycomb.translate.spi.read.ListReaderCustomizer;
+import java.util.List;
+import java.util.stream.Collectors;
+import javax.annotation.Nonnull;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfaceId;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfacesStateBuilder;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.state.Interface;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.state.InterfaceBuilder;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.state.InterfaceKey;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is a customizer responsible for reading Interface operational data
+ */
+public class InterfaceReaderCustomizer implements ListReaderCustomizer<Interface, InterfaceKey, InterfaceBuilder> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(InterfaceReaderCustomizer.class);
+    private final LowerLayerAccess access;
+
+    public InterfaceReaderCustomizer(final LowerLayerAccess access) {
+        this.access = access;
+    }
+
+    @Nonnull
+    @Override
+    public List<InterfaceKey> getAllIds(@Nonnull final InstanceIdentifier<Interface> id,
+                                        @Nonnull final ReadContext context) throws ReadFailedException {
+        // context can be used to access cache (lifetime during a transaction) to store any information for
+        // subsequent invocations or for other customizers
+        // context.getModificationCache();
+
+        // context can also be used to access context data. Context data are stored in a persistent data store
+        // and usually are additional data required to perform the translation in customizers e.g. if underlying layer
+        // does not recognize interface-ids as string names, but only indices, the mapping between them can should
+        // be stored in the context data store
+        // Note: The context datastore is also YANG drive, so context data must be modeled in YANG prior to using them
+        // context.getMappingContext();
+
+        // return some sample IDs
+        return access.getAllInterfaceNames().stream()
+                .map(InterfaceId::new)
+                .map(InterfaceKey::new)
+                .collect(Collectors.toList());
+    }
+
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> builder, @Nonnull final List<Interface> readData) {
+        // Just set the result of this customizers read into parent builder
+        // Builder has to be cast properly
+        ((InterfacesStateBuilder) builder).setInterface(readData);
+    }
+
+    @Nonnull
+    @Override
+    public InterfaceBuilder getBuilder(@Nonnull final InstanceIdentifier<Interface> id) {
+        // Just providing empty builder
+        return new InterfaceBuilder();
+    }
+
+    @Override
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<Interface> id,
+                                      @Nonnull final InterfaceBuilder builder, @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        // This is where the actual "read" is happening, read attributes for a specific interface
+        final InterfaceKey k = id.firstKeyOf(Interface.class);
+        final String ifcId = k.getInterfaceId().getValue();
+        LOG.info("Reading data for interface: {} at {}", ifcId, id);
+
+        // Fill in some random values, this is actually the place where communication with lower layer
+        // would occur to get the real values
+        builder.setMtu(access.getMtuForInterface(ifcId));
+        builder.setInterfaceId(k.getInterfaceId());
+        // Counters container is not set here, instead a dedicated customizer is created for it
+        // It could be set here, if this customizer + its reader were marked as subtree reader in the ReaderFactory
+        // However its a good practice to provide a dedicated reader+customizer for every complex node
+    }
+
+}
diff --git a/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/InterfacesReaderFactory.java b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/InterfacesReaderFactory.java
new file mode 100644
index 000000000..5e34eea74
--- /dev/null
+++ b/samples/interfaces/mapping/src/main/java/io/fd/honeycomb/samples/interfaces/mapping/oper/InterfacesReaderFactory.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.samples.interfaces.mapping.oper;
+
+import com.google.inject.Inject;
+import io.fd.honeycomb.samples.interfaces.mapping.LowerLayerAccess;
+import io.fd.honeycomb.translate.impl.read.GenericListReader;
+import io.fd.honeycomb.translate.impl.read.GenericReader;
+import io.fd.honeycomb.translate.read.ReaderFactory;
+import io.fd.honeycomb.translate.read.registry.ModifiableReaderRegistryBuilder;
+import javax.annotation.Nonnull;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfacesState;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.InterfacesStateBuilder;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810._interface.state.Counters;
+import org.opendaylight.yang.gen.v1.io.fd.honeycomb.samples.interfaces.rev160810.interfaces.state.Interface;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class InterfacesReaderFactory implements ReaderFactory {
+
+    @Nonnull
+    private final LowerLayerAccess access;
+
+    @Inject
+    public InterfacesReaderFactory(@Nonnull final LowerLayerAccess access) {
+        this.access = access;
+    }
+
+    @Override
+    public void init(@Nonnull final ModifiableReaderRegistryBuilder registry) {
+        // ReaderFactory is intended for registering Readers into HC framework
+        // Readers provide ONLY operational (config "false") data straight from underlying device/layer
+        // they are triggered when RESTCONF GET on operational is invoked or when NETCONF get operation is executed
+
+        // Our model root for operational data is InterfacesState
+        final InstanceIdentifier<InterfacesState> root = InstanceIdentifier.create(InterfacesState.class);
+        // Since InterfacesState has no direct data children (leaves) only a structural reader is registered
+        // This reader just fills in the composite hierarchy of readers
+        // Honeycomb can't automatically instantiate structural readers and plugins have to help it by invoking as:
+        registry.addStructuralReader(root, InterfacesStateBuilder.class);
+
+        // Next child node is Interface (list)
+        final InstanceIdentifier<Interface> ifcListId = root.child(Interface.class);
+        registry.add(new GenericListReader<>(ifcListId, new InterfaceReaderCustomizer(access)));
+
+        // Next child is a container Counters
+        final InstanceIdentifier<Counters> countersId = ifcListId.child(Counters.class);
+        // By adding the reader with addAfter, we can ensure ordering of execution among the readers
+        // Useful in cases when a certain read has to be invoked before/after another
+        // In this case, we are ensuring that Counters are read after Interface is read
+        // "add" could be used instead, leaving the ordering to "nature"
+        // Same applies for writers
+        registry.addAfter(new GenericReader<>(countersId, new CountersReaderCustomizer(access)), ifcListId);
+    }
+}