netconf/sal-netconf-connector/src/main/java/org/opendaylight/netconf/sal/connect/netconf/NetconfDevice.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.netconf.sal.connect.netconf;
   9
  10 import static com.google.common.base.Preconditions.checkState;
  11 import static java.util.Objects.requireNonNull;
  12
  13 import com.google.common.base.Predicates;
  14 import com.google.common.collect.Collections2;
  15 import com.google.common.collect.Lists;
  16 import com.google.common.collect.Sets;
  17 import com.google.common.util.concurrent.FutureCallback;
  18 import com.google.common.util.concurrent.Futures;
  19 import com.google.common.util.concurrent.ListenableFuture;
  20 import com.google.common.util.concurrent.ListeningExecutorService;
  21 import com.google.common.util.concurrent.MoreExecutors;
  22 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  23 import io.netty.util.concurrent.EventExecutor;
  24 import java.util.ArrayList;
  25 import java.util.Collection;
  26 import java.util.Collections;
  27 import java.util.LinkedList;
  28 import java.util.List;
  29 import java.util.Optional;
  30 import java.util.Set;
  31 import java.util.concurrent.ExecutionException;
  32 import java.util.concurrent.TimeUnit;
  33 import java.util.stream.Collectors;
  34 import org.checkerframework.checker.lock.qual.GuardedBy;
  35 import org.opendaylight.mdsal.dom.api.DOMRpcResult;
  36 import org.opendaylight.mdsal.dom.api.DOMRpcService;
  37 import org.opendaylight.netconf.api.NetconfMessage;
  38 import org.opendaylight.netconf.sal.connect.api.DeviceActionFactory;
  39 import org.opendaylight.netconf.sal.connect.api.MessageTransformer;
  40 import org.opendaylight.netconf.sal.connect.api.NetconfDeviceSchemasResolver;
  41 import org.opendaylight.netconf.sal.connect.api.RemoteDevice;
  42 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceCommunicator;
  43 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceHandler;
  44 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCapabilities;
  45 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCommunicator;
  46 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfSessionPreferences;
  47 import org.opendaylight.netconf.sal.connect.netconf.sal.NetconfDeviceRpc;
  48 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.BaseSchema;
  49 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.NetconfMessageTransformer;
  50 import org.opendaylight.netconf.sal.connect.netconf.util.NetconfMessageTransformUtil;
  51 import org.opendaylight.netconf.sal.connect.util.RemoteDeviceId;
  52 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.notifications.rev120206.NetconfCapabilityChange;
  53 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.optional.rev190614.NetconfNodeAugmentedOptional;
  54 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.NetconfNode;
  55 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.available.capabilities.AvailableCapabilityBuilder;
  56 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.unavailable.capabilities.UnavailableCapability;
  57 import org.opendaylight.yangtools.rcf8528.data.util.EmptyMountPointContext;
  58 import org.opendaylight.yangtools.rfc8528.data.api.MountPointContext;
  59 import org.opendaylight.yangtools.yang.common.QName;
  60 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  61 import org.opendaylight.yangtools.yang.model.repo.api.MissingSchemaSourceException;
  62 import org.opendaylight.yangtools.yang.model.repo.api.SchemaContextFactory;
  63 import org.opendaylight.yangtools.yang.model.repo.api.SchemaRepository;
  64 import org.opendaylight.yangtools.yang.model.repo.api.SchemaResolutionException;
  65 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  66 import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
  67 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
  68 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
  69 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistration;
  70 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistry;
  71 import org.slf4j.Logger;
  72 import org.slf4j.LoggerFactory;
  73
  74 /**
  75  *  This is a mediator between NetconfDeviceCommunicator and NetconfDeviceSalFacade.
  76  */
  77 public class NetconfDevice
  78         implements RemoteDevice<NetconfSessionPreferences, NetconfMessage, NetconfDeviceCommunicator> {
  79
  80     @SuppressFBWarnings(value = "SLF4J_LOGGER_SHOULD_BE_PRIVATE",
  81             justification = "Needed for common logging of related classes")
  82     static final Logger LOG = LoggerFactory.getLogger(NetconfDevice.class);
  83
  84     protected final RemoteDeviceId id;
  85     protected final SchemaContextFactory schemaContextFactory;
  86     protected final SchemaSourceRegistry schemaRegistry;
  87     protected final SchemaRepository schemaRepository;
  88
  89     protected final List<SchemaSourceRegistration<?>> sourceRegistrations = new ArrayList<>();
  90
  91     private final RemoteDeviceHandler<NetconfSessionPreferences> salFacade;
  92     private final ListeningExecutorService processingExecutor;
  93     private final DeviceActionFactory deviceActionFactory;
  94     private final NetconfDeviceSchemasResolver stateSchemasResolver;
  95     private final NotificationHandler notificationHandler;
  96     private final boolean reconnectOnSchemasChange;
  97     private final NetconfNode node;
  98     private final EventExecutor eventExecutor;
  99     private final NetconfNodeAugmentedOptional nodeOptional;
 100
 101     @GuardedBy("this")
 102     private boolean connected = false;
 103
 104     // Message transformer is constructed once the schemas are available
 105     private MessageTransformer<NetconfMessage> messageTransformer;
 106
 107     public NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id,
 108                          final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 109                          final ListeningExecutorService globalProcessingExecutor,
 110                          final boolean reconnectOnSchemasChange) {
 111         this(schemaResourcesDTO, id, salFacade, globalProcessingExecutor, reconnectOnSchemasChange, null, null, null,
 112                 null);
 113     }
 114
 115     public NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id,
 116             final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 117             final ListeningExecutorService globalProcessingExecutor, final boolean reconnectOnSchemasChange,
 118             final DeviceActionFactory deviceActionFactory, final NetconfNode node, final EventExecutor eventExecutor,
 119             final NetconfNodeAugmentedOptional nodeOptional) {
 120         this.id = id;
 121         this.reconnectOnSchemasChange = reconnectOnSchemasChange;
 122         this.deviceActionFactory = deviceActionFactory;
 123         this.node = node;
 124         this.eventExecutor = eventExecutor;
 125         this.nodeOptional = nodeOptional;
 126         this.schemaRegistry = schemaResourcesDTO.getSchemaRegistry();
 127         this.schemaRepository = schemaResourcesDTO.getSchemaRepository();
 128         this.schemaContextFactory = schemaResourcesDTO.getSchemaContextFactory();
 129         this.salFacade = salFacade;
 130         this.stateSchemasResolver = schemaResourcesDTO.getStateSchemasResolver();
 131         this.processingExecutor = requireNonNull(globalProcessingExecutor);
 132         this.notificationHandler = new NotificationHandler(salFacade, id);
 133     }
 134
 135     @Override
 136     public void onRemoteSessionUp(final NetconfSessionPreferences remoteSessionCapabilities,
 137                                   final NetconfDeviceCommunicator listener) {
 138         // SchemaContext setup has to be performed in a dedicated thread since
 139         // we are in a netty thread in this method
 140         // Yang models are being downloaded in this method and it would cause a
 141         // deadlock if we used the netty thread
 142         // http://netty.io/wiki/thread-model.html
 143         setConnected(true);
 144         LOG.debug("{}: Session to remote device established with {}", id, remoteSessionCapabilities);
 145
 146         final BaseSchema baseSchema = resolveBaseSchema(remoteSessionCapabilities.isNotificationsSupported());
 147         final NetconfDeviceRpc initRpc = new NetconfDeviceRpc(baseSchema.getSchemaContext(), listener,
 148             new NetconfMessageTransformer(baseSchema.getMountPointContext(), false, baseSchema));
 149         final ListenableFuture<DeviceSources> sourceResolverFuture = processingExecutor.submit(
 150             new DeviceSourcesResolver(id, baseSchema, initRpc, remoteSessionCapabilities, stateSchemasResolver));
 151
 152         if (shouldListenOnSchemaChange(remoteSessionCapabilities)) {
 153             registerToBaseNetconfStream(initRpc, listener);
 154         }
 155
 156         final FutureCallback<DeviceSources> resolvedSourceCallback = new FutureCallback<DeviceSources>() {
 157             @Override
 158             public void onSuccess(final DeviceSources result) {
 159                 addProvidedSourcesToSchemaRegistry(result);
 160                 setUpSchema(result);
 161             }
 162
 163             private void setUpSchema(final DeviceSources result) {
 164                 processingExecutor.submit(new SchemaSetup(result, remoteSessionCapabilities, listener));
 165             }
 166
 167             @Override
 168             public void onFailure(final Throwable throwable) {
 169                 LOG.warn("{}: Unexpected error resolving device sources", id, throwable);
 170                 handleSalInitializationFailure(throwable, listener);
 171             }
 172         };
 173
 174         Futures.addCallback(sourceResolverFuture, resolvedSourceCallback, MoreExecutors.directExecutor());
 175     }
 176
 177     private void registerToBaseNetconfStream(final NetconfDeviceRpc deviceRpc,
 178                                              final NetconfDeviceCommunicator listener) {
 179         // TODO check whether the model describing create subscription is present in schema
 180         // Perhaps add a default schema context to support create-subscription if the model was not provided
 181         // (same as what we do for base netconf operations in transformer)
 182         final ListenableFuture<DOMRpcResult> rpcResultListenableFuture = deviceRpc.invokeRpc(
 183                 NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_PATH,
 184                 NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_CONTENT);
 185
 186         Futures.addCallback(rpcResultListenableFuture, new FutureCallback<DOMRpcResult>() {
 187             @Override
 188             public void onSuccess(final DOMRpcResult domRpcResult) {
 189                 notificationHandler.addNotificationFilter(notification -> {
 190                     if (NetconfCapabilityChange.QNAME.equals(notification.getBody().getNodeType())) {
 191                         LOG.info("{}: Schemas change detected, reconnecting", id);
 192                         // Only disconnect is enough,
 193                         // the reconnecting nature of the connector will take care of reconnecting
 194                         listener.disconnect();
 195                         return Optional.empty();
 196                     }
 197                     return Optional.of(notification);
 198                 });
 199             }
 200
 201             @Override
 202             public void onFailure(final Throwable throwable) {
 203                 LOG.warn("Unable to subscribe to base notification stream. Schemas will not be reloaded on the fly",
 204                         throwable);
 205             }
 206         }, MoreExecutors.directExecutor());
 207     }
 208
 209     private boolean shouldListenOnSchemaChange(final NetconfSessionPreferences remoteSessionCapabilities) {
 210         return remoteSessionCapabilities.isNotificationsSupported() && reconnectOnSchemasChange;
 211     }
 212
 213     private synchronized void handleSalInitializationSuccess(final MountPointContext result,
 214                                         final NetconfSessionPreferences remoteSessionCapabilities,
 215                                         final DOMRpcService deviceRpc,
 216                                         final RemoteDeviceCommunicator<NetconfMessage> listener) {
 217         //NetconfDevice.SchemaSetup can complete after NetconfDeviceCommunicator was closed. In that case do nothing,
 218         //since salFacade.onDeviceDisconnected was already called.
 219         if (connected) {
 220             final BaseSchema baseSchema =
 221                 remoteSessionCapabilities.isNotificationsSupported()
 222                         ? BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS : BaseSchema.BASE_NETCONF_CTX;
 223             this.messageTransformer = new NetconfMessageTransformer(result, true, baseSchema);
 224
 225             // salFacade.onDeviceConnected has to be called before the notification handler is initialized
 226             this.salFacade.onDeviceConnected(result, remoteSessionCapabilities, deviceRpc,
 227                     this.deviceActionFactory == null ? null : this.deviceActionFactory.createDeviceAction(
 228                             this.messageTransformer, listener, result.getSchemaContext()));
 229             this.notificationHandler.onRemoteSchemaUp(this.messageTransformer);
 230
 231             LOG.info("{}: Netconf connector initialized successfully", id);
 232         } else {
 233             LOG.warn("{}: Device communicator was closed before schema setup finished.", id);
 234         }
 235     }
 236
 237     private void handleSalInitializationFailure(final Throwable throwable,
 238                                                 final RemoteDeviceCommunicator<NetconfMessage> listener) {
 239         LOG.error("{}: Initialization in sal failed, disconnecting from device", id, throwable);
 240         listener.close();
 241         onRemoteSessionDown();
 242         resetMessageTransformer();
 243     }
 244
 245     /**
 246      * Set the transformer to null as is in initial state.
 247      */
 248     private void resetMessageTransformer() {
 249         updateTransformer(null);
 250     }
 251
 252     private synchronized void updateTransformer(final MessageTransformer<NetconfMessage> transformer) {
 253         messageTransformer = transformer;
 254     }
 255
 256     private synchronized void setConnected(final boolean connected) {
 257         this.connected = connected;
 258     }
 259
 260     private void addProvidedSourcesToSchemaRegistry(final DeviceSources deviceSources) {
 261         final SchemaSourceProvider<YangTextSchemaSource> yangProvider = deviceSources.getSourceProvider();
 262         for (final SourceIdentifier sourceId : deviceSources.getProvidedSources()) {
 263             sourceRegistrations.add(schemaRegistry.registerSchemaSource(yangProvider,
 264                     PotentialSchemaSource.create(
 265                             sourceId, YangTextSchemaSource.class, PotentialSchemaSource.Costs.REMOTE_IO.getValue())));
 266         }
 267     }
 268
 269     @Override
 270     public void onRemoteSessionDown() {
 271         setConnected(false);
 272         notificationHandler.onRemoteSchemaDown();
 273
 274         salFacade.onDeviceDisconnected();
 275         sourceRegistrations.forEach(SchemaSourceRegistration::close);
 276         sourceRegistrations.clear();
 277         resetMessageTransformer();
 278     }
 279
 280     @Override
 281     public void onRemoteSessionFailed(final Throwable throwable) {
 282         setConnected(false);
 283         salFacade.onDeviceFailed(throwable);
 284     }
 285
 286     @Override
 287     public void onNotification(final NetconfMessage notification) {
 288         notificationHandler.handleNotification(notification);
 289     }
 290
 291     private static BaseSchema resolveBaseSchema(final boolean notificationSupport) {
 292         return notificationSupport ? BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS : BaseSchema.BASE_NETCONF_CTX;
 293     }
 294
 295     /**
 296      * Just a transfer object containing schema related dependencies. Injected in constructor.
 297      */
 298     public static class SchemaResourcesDTO {
 299         private final SchemaSourceRegistry schemaRegistry;
 300         private final SchemaRepository schemaRepository;
 301         private final SchemaContextFactory schemaContextFactory;
 302         private final NetconfDeviceSchemasResolver stateSchemasResolver;
 303
 304         public SchemaResourcesDTO(final SchemaSourceRegistry schemaRegistry,
 305                                   final SchemaRepository schemaRepository,
 306                                   final SchemaContextFactory schemaContextFactory,
 307                                   final NetconfDeviceSchemasResolver deviceSchemasResolver) {
 308             this.schemaRegistry = requireNonNull(schemaRegistry);
 309             this.schemaRepository = requireNonNull(schemaRepository);
 310             this.schemaContextFactory = requireNonNull(schemaContextFactory);
 311             this.stateSchemasResolver = requireNonNull(deviceSchemasResolver);
 312         }
 313
 314         public SchemaSourceRegistry getSchemaRegistry() {
 315             return schemaRegistry;
 316         }
 317
 318         public SchemaRepository getSchemaRepository() {
 319             return schemaRepository;
 320         }
 321
 322         public SchemaContextFactory getSchemaContextFactory() {
 323             return schemaContextFactory;
 324         }
 325
 326         public NetconfDeviceSchemasResolver getStateSchemasResolver() {
 327             return stateSchemasResolver;
 328         }
 329     }
 330
 331     /**
 332      * Schema builder that tries to build schema context from provided sources or biggest subset of it.
 333      */
 334     private final class SchemaSetup implements Runnable {
 335         private final DeviceSources deviceSources;
 336         private final NetconfSessionPreferences remoteSessionCapabilities;
 337         private final RemoteDeviceCommunicator<NetconfMessage> listener;
 338         private final NetconfDeviceCapabilities capabilities;
 339
 340         SchemaSetup(final DeviceSources deviceSources, final NetconfSessionPreferences remoteSessionCapabilities,
 341                            final RemoteDeviceCommunicator<NetconfMessage> listener) {
 342             this.deviceSources = deviceSources;
 343             this.remoteSessionCapabilities = remoteSessionCapabilities;
 344             this.listener = listener;
 345             this.capabilities = remoteSessionCapabilities.getNetconfDeviceCapabilities();
 346         }
 347
 348         @Override
 349         public void run() {
 350
 351             final Collection<SourceIdentifier> requiredSources = deviceSources.getRequiredSources();
 352             final Collection<SourceIdentifier> missingSources = filterMissingSources(requiredSources);
 353
 354             capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(missingSources),
 355                     UnavailableCapability.FailureReason.MissingSource);
 356
 357             requiredSources.removeAll(missingSources);
 358             setUpSchema(requiredSources);
 359         }
 360
 361         private Collection<SourceIdentifier> filterMissingSources(final Collection<SourceIdentifier> requiredSources) {
 362             return requiredSources.parallelStream().filter(sourceIdentifier -> {
 363                 try {
 364                     schemaRepository.getSchemaSource(sourceIdentifier, YangTextSchemaSource.class).get();
 365                     return false;
 366                 } catch (InterruptedException | ExecutionException e) {
 367                     return true;
 368                 }
 369             }).collect(Collectors.toList());
 370         }
 371
 372         /**
 373          * Build schema context, in case of success or final failure notify device.
 374          *
 375          * @param requiredSources required sources
 376          */
 377         @SuppressWarnings("checkstyle:IllegalCatch")
 378         private void setUpSchema(Collection<SourceIdentifier> requiredSources) {
 379             while (!requiredSources.isEmpty()) {
 380                 LOG.trace("{}: Trying to build schema context from {}", id, requiredSources);
 381                 try {
 382                     final ListenableFuture<SchemaContext> schemaBuilderFuture = schemaContextFactory
 383                             .createSchemaContext(requiredSources);
 384                     final SchemaContext result = schemaBuilderFuture.get();
 385                     LOG.debug("{}: Schema context built successfully from {}", id, requiredSources);
 386                     final Collection<QName> filteredQNames = Sets.difference(deviceSources.getRequiredSourcesQName(),
 387                             capabilities.getUnresolvedCapabilites().keySet());
 388                     capabilities.addCapabilities(filteredQNames.stream().map(entry -> new AvailableCapabilityBuilder()
 389                             .setCapability(entry.toString()).setCapabilityOrigin(
 390                                     remoteSessionCapabilities.getModuleBasedCapsOrigin().get(entry)).build())
 391                             .collect(Collectors.toList()));
 392
 393                     capabilities.addNonModuleBasedCapabilities(remoteSessionCapabilities
 394                             .getNonModuleCaps().stream().map(entry -> new AvailableCapabilityBuilder()
 395                                     .setCapability(entry).setCapabilityOrigin(
 396                                             remoteSessionCapabilities.getNonModuleBasedCapsOrigin().get(entry)).build())
 397                             .collect(Collectors.toList()));
 398
 399                     final MountPointContext mountContext = new EmptyMountPointContext(result);
 400                     handleSalInitializationSuccess(mountContext, remoteSessionCapabilities,
 401                         getDeviceSpecificRpc(mountContext), listener);
 402                     return;
 403                 } catch (final ExecutionException e) {
 404                     // schemaBuilderFuture.checkedGet() throws only SchemaResolutionException
 405                     // that might be wrapping a MissingSchemaSourceException so we need to look
 406                     // at the cause of the exception to make sure we don't misinterpret it.
 407                     final Throwable cause = e.getCause();
 408
 409                     if (cause instanceof MissingSchemaSourceException) {
 410                         requiredSources = handleMissingSchemaSourceException(
 411                                 requiredSources, (MissingSchemaSourceException) cause);
 412                         continue;
 413                     }
 414                     if (cause instanceof SchemaResolutionException) {
 415                         requiredSources = handleSchemaResolutionException(requiredSources,
 416                             (SchemaResolutionException) cause);
 417                     } else {
 418                         handleSalInitializationFailure(e, listener);
 419                         return;
 420                     }
 421                 } catch (final Exception e) {
 422                     // unknown error, fail
 423                     handleSalInitializationFailure(e, listener);
 424                     return;
 425                 }
 426             }
 427             // No more sources, fail or try to reconnect
 428             if (nodeOptional != null && nodeOptional.getIgnoreMissingSchemaSources().isAllowed()) {
 429                 eventExecutor.schedule(() -> {
 430                     LOG.warn("Reconnection is allowed! This can lead to unexpected errors at runtime.");
 431                     LOG.warn("{} : No more sources for schema context.", id);
 432                     LOG.info("{} : Try to remount device.", id);
 433                     onRemoteSessionDown();
 434                     salFacade.onDeviceReconnected(remoteSessionCapabilities, node);
 435                 }, nodeOptional.getIgnoreMissingSchemaSources().getReconnectTime(), TimeUnit.MILLISECONDS);
 436             } else {
 437                 final IllegalStateException cause =
 438                         new IllegalStateException(id + ": No more sources for schema context");
 439                 handleSalInitializationFailure(cause, listener);
 440                 salFacade.onDeviceFailed(cause);
 441             }
 442         }
 443
 444         private Collection<SourceIdentifier> handleMissingSchemaSourceException(
 445                 final Collection<SourceIdentifier> requiredSources, final MissingSchemaSourceException exception) {
 446             // In case source missing, try without it
 447             final SourceIdentifier missingSource = exception.getSourceId();
 448             LOG.warn("{}: Unable to build schema context, missing source {}, will reattempt without it",
 449                 id, missingSource);
 450             LOG.debug("{}: Unable to build schema context, missing source {}, will reattempt without it",
 451                 id, missingSource, exception);
 452             final Collection<QName> qNameOfMissingSource =
 453                 getQNameFromSourceIdentifiers(Sets.newHashSet(missingSource));
 454             if (!qNameOfMissingSource.isEmpty()) {
 455                 capabilities.addUnresolvedCapabilities(
 456                         qNameOfMissingSource, UnavailableCapability.FailureReason.MissingSource);
 457             }
 458             return stripUnavailableSource(requiredSources, missingSource);
 459         }
 460
 461         private Collection<SourceIdentifier> handleSchemaResolutionException(
 462             final Collection<SourceIdentifier> requiredSources, final SchemaResolutionException resolutionException) {
 463             // In case resolution error, try only with resolved sources
 464             // There are two options why schema resolution exception occurred : unsatisfied imports or flawed model
 465             // FIXME Do we really have assurance that these two cases cannot happen at once?
 466             if (resolutionException.getFailedSource() != null) {
 467                 // flawed model - exclude it
 468                 final SourceIdentifier failedSourceId = resolutionException.getFailedSource();
 469                 LOG.warn("{}: Unable to build schema context, failed to resolve source {}, will reattempt without it",
 470                     id, failedSourceId);
 471                 LOG.warn("{}: Unable to build schema context, failed to resolve source {}, will reattempt without it",
 472                     id, failedSourceId, resolutionException);
 473                 capabilities.addUnresolvedCapabilities(
 474                         getQNameFromSourceIdentifiers(Collections.singleton(failedSourceId)),
 475                         UnavailableCapability.FailureReason.UnableToResolve);
 476                 return stripUnavailableSource(requiredSources, resolutionException.getFailedSource());
 477             }
 478             // unsatisfied imports
 479             final Set<SourceIdentifier> unresolvedSources = resolutionException.getUnsatisfiedImports().keySet();
 480             capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(unresolvedSources),
 481                 UnavailableCapability.FailureReason.UnableToResolve);
 482             LOG.warn("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only",
 483                 id, resolutionException.getUnsatisfiedImports());
 484             LOG.debug("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only",
 485                 id, resolutionException.getUnsatisfiedImports(), resolutionException);
 486             return resolutionException.getResolvedSources();
 487         }
 488
 489         protected NetconfDeviceRpc getDeviceSpecificRpc(final MountPointContext result) {
 490             return new NetconfDeviceRpc(result.getSchemaContext(), listener,
 491                 new NetconfMessageTransformer(result, true));
 492         }
 493
 494         private Collection<SourceIdentifier> stripUnavailableSource(final Collection<SourceIdentifier> requiredSources,
 495                                                                     final SourceIdentifier sourceIdToRemove) {
 496             final LinkedList<SourceIdentifier> sourceIdentifiers = Lists.newLinkedList(requiredSources);
 497             checkState(sourceIdentifiers.remove(sourceIdToRemove),
 498                     "%s: Trying to remove %s from %s failed", id, sourceIdToRemove, requiredSources);
 499             return sourceIdentifiers;
 500         }
 501
 502         private Collection<QName> getQNameFromSourceIdentifiers(final Collection<SourceIdentifier> identifiers) {
 503             final Collection<QName> qNames = Collections2.transform(identifiers, this::getQNameFromSourceIdentifier);
 504
 505             if (qNames.isEmpty()) {
 506                 LOG.debug("{}: Unable to map any source identifiers to a capability reported by device : {}", id,
 507                         identifiers);
 508             }
 509             return Collections2.filter(qNames, Predicates.notNull());
 510         }
 511
 512         private QName getQNameFromSourceIdentifier(final SourceIdentifier identifier) {
 513             // Required sources are all required and provided merged in DeviceSourcesResolver
 514             for (final QName qname : deviceSources.getRequiredSourcesQName()) {
 515                 if (!qname.getLocalName().equals(identifier.getName())) {
 516                     continue;
 517                 }
 518
 519                 if (identifier.getRevision().equals(qname.getRevision())) {
 520                     return qname;
 521                 }
 522             }
 523             LOG.warn("Unable to map identifier to a devices reported capability: {} Available: {}",identifier,
 524                     deviceSources.getRequiredSourcesQName());
 525             // return null since we cannot find the QName,
 526             // this capability will be removed from required sources and not reported as unresolved-capability
 527             return null;
 528         }
 529     }
 530 }