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 com.google.common.base.Function;
  11 import com.google.common.base.Optional;
  12 import com.google.common.base.Preconditions;
  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.CheckedFuture;
  18 import com.google.common.util.concurrent.FutureCallback;
  19 import com.google.common.util.concurrent.Futures;
  20 import com.google.common.util.concurrent.ListenableFuture;
  21 import com.google.common.util.concurrent.ListeningExecutorService;
  22 import com.google.common.util.concurrent.MoreExecutors;
  23 import java.util.Collection;
  24 import java.util.LinkedList;
  25 import java.util.List;
  26 import java.util.Set;
  27 import java.util.concurrent.Callable;
  28 import java.util.concurrent.ExecutorService;
  29 import org.opendaylight.controller.md.sal.dom.api.DOMNotification;
  30 import org.opendaylight.controller.md.sal.dom.api.DOMRpcException;
  31 import org.opendaylight.controller.md.sal.dom.api.DOMRpcResult;
  32 import org.opendaylight.controller.md.sal.dom.api.DOMRpcService;
  33 import org.opendaylight.netconf.api.NetconfMessage;
  34 import org.opendaylight.netconf.sal.connect.api.MessageTransformer;
  35 import org.opendaylight.netconf.sal.connect.api.NetconfDeviceSchemas;
  36 import org.opendaylight.netconf.sal.connect.api.NetconfDeviceSchemasResolver;
  37 import org.opendaylight.netconf.sal.connect.api.RemoteDevice;
  38 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceCommunicator;
  39 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceHandler;
  40 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCapabilities;
  41 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCommunicator;
  42 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfSessionPreferences;
  43 import org.opendaylight.netconf.sal.connect.netconf.sal.NetconfDeviceRpc;
  44 import org.opendaylight.netconf.sal.connect.netconf.schema.NetconfRemoteSchemaYangSourceProvider;
  45 import org.opendaylight.netconf.sal.connect.netconf.schema.YangLibrarySchemaYangSourceProvider;
  46 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.BaseSchema;
  47 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.NetconfMessageTransformer;
  48 import org.opendaylight.netconf.sal.connect.netconf.util.NetconfMessageTransformUtil;
  49 import org.opendaylight.netconf.sal.connect.util.RemoteDeviceId;
  50 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.notifications.rev120206.NetconfCapabilityChange;
  51 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.unavailable.capabilities.UnavailableCapability;
  52 import org.opendaylight.yangtools.yang.common.QName;
  53 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  54 import org.opendaylight.yangtools.yang.model.repo.api.MissingSchemaSourceException;
  55 import org.opendaylight.yangtools.yang.model.repo.api.RevisionSourceIdentifier;
  56 import org.opendaylight.yangtools.yang.model.repo.api.SchemaContextFactory;
  57 import org.opendaylight.yangtools.yang.model.repo.api.SchemaResolutionException;
  58 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceRepresentation;
  59 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  60 import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
  61 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
  62 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
  63 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistration;
  64 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistry;
  65 import org.slf4j.Logger;
  66 import org.slf4j.LoggerFactory;
  67
  68 /**
  69  *  This is a mediator between NetconfDeviceCommunicator and NetconfDeviceSalFacade
  70  */
  71 public class NetconfDevice implements RemoteDevice<NetconfSessionPreferences, NetconfMessage, NetconfDeviceCommunicator> {
  72
  73     private static final Logger LOG = LoggerFactory.getLogger(NetconfDevice.class);
  74
  75     public static final Function<QName, SourceIdentifier> QNAME_TO_SOURCE_ID_FUNCTION = new Function<QName, SourceIdentifier>() {
  76         @Override
  77         public SourceIdentifier apply(final QName input) {
  78             return RevisionSourceIdentifier
  79                     .create(input.getLocalName(), Optional.fromNullable(input.getFormattedRevision()));
  80         }
  81     };
  82
  83     protected final RemoteDeviceId id;
  84     private final boolean reconnectOnSchemasChange;
  85
  86     protected final SchemaContextFactory schemaContextFactory;
  87     private final RemoteDeviceHandler<NetconfSessionPreferences> salFacade;
  88     private final ListeningExecutorService processingExecutor;
  89     protected final SchemaSourceRegistry schemaRegistry;
  90     private final NetconfDeviceSchemasResolver stateSchemasResolver;
  91     private final NotificationHandler notificationHandler;
  92     protected final List<SchemaSourceRegistration<? extends SchemaSourceRepresentation>> sourceRegistrations = Lists.newArrayList();
  93
  94     // Message transformer is constructed once the schemas are available
  95     private MessageTransformer<NetconfMessage> messageTransformer;
  96
  97     /**
  98      * Create rpc implementation capable of handling RPC for monitoring and notifications even before the schemas of remote device are downloaded
  99      */
 100     static NetconfDeviceRpc getRpcForInitialization(final NetconfDeviceCommunicator listener, final boolean notificationSupport) {
 101         final BaseSchema baseSchema = notificationSupport ?
 102                 BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS :
 103                 BaseSchema.BASE_NETCONF_CTX;
 104
 105         return new NetconfDeviceRpc(baseSchema.getSchemaContext(), listener, new NetconfMessageTransformer(baseSchema.getSchemaContext(), false, baseSchema));
 106     }
 107
 108     protected NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id, final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 109                          final ExecutorService globalProcessingExecutor, final boolean reconnectOnSchemasChange) {
 110         this.id = id;
 111         this.reconnectOnSchemasChange = reconnectOnSchemasChange;
 112         this.schemaRegistry = schemaResourcesDTO.getSchemaRegistry();
 113         this.schemaContextFactory = schemaResourcesDTO.getSchemaContextFactory();
 114         this.salFacade = salFacade;
 115         this.stateSchemasResolver = schemaResourcesDTO.getStateSchemasResolver();
 116         this.processingExecutor = MoreExecutors.listeningDecorator(globalProcessingExecutor);
 117         this.notificationHandler = new NotificationHandler(salFacade, id);
 118     }
 119
 120     @Override
 121     public void onRemoteSessionUp(final NetconfSessionPreferences remoteSessionCapabilities,
 122                                   final NetconfDeviceCommunicator listener) {
 123         // SchemaContext setup has to be performed in a dedicated thread since
 124         // we are in a netty thread in this method
 125         // Yang models are being downloaded in this method and it would cause a
 126         // deadlock if we used the netty thread
 127         // http://netty.io/wiki/thread-model.html
 128         LOG.debug("{}: Session to remote device established with {}", id, remoteSessionCapabilities);
 129
 130         final NetconfDeviceRpc initRpc = getRpcForInitialization(listener, remoteSessionCapabilities.isNotificationsSupported());
 131         final DeviceSourcesResolver task = new DeviceSourcesResolver(remoteSessionCapabilities, id, stateSchemasResolver, initRpc);
 132         final ListenableFuture<DeviceSources> sourceResolverFuture = processingExecutor.submit(task);
 133
 134         if (shouldListenOnSchemaChange(remoteSessionCapabilities)) {
 135             registerToBaseNetconfStream(initRpc, listener);
 136         }
 137
 138         final FutureCallback<DeviceSources> resolvedSourceCallback = new FutureCallback<DeviceSources>() {
 139             @Override
 140             public void onSuccess(final DeviceSources result) {
 141                 addProvidedSourcesToSchemaRegistry(result);
 142                 setUpSchema(result);
 143             }
 144
 145             private void setUpSchema(final DeviceSources result) {
 146                 processingExecutor.submit(new SchemaSetup(result, remoteSessionCapabilities, listener));
 147             }
 148
 149             @Override
 150             public void onFailure(final Throwable t) {
 151                 LOG.warn("{}: Unexpected error resolving device sources: {}", id, t);
 152                 handleSalInitializationFailure(t, listener);
 153             }
 154         };
 155
 156         Futures.addCallback(sourceResolverFuture, resolvedSourceCallback);
 157     }
 158
 159     private void registerToBaseNetconfStream(final NetconfDeviceRpc deviceRpc, final NetconfDeviceCommunicator listener) {
 160        // TODO check whether the model describing create subscription is present in schema
 161         // Perhaps add a default schema context to support create-subscription if the model was not provided (same as what we do for base netconf operations in transformer)
 162         final CheckedFuture<DOMRpcResult, DOMRpcException> rpcResultListenableFuture =
 163                 deviceRpc.invokeRpc(NetconfMessageTransformUtil.toPath(NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_QNAME), NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_CONTENT);
 164
 165         final NotificationHandler.NotificationFilter filter = new NotificationHandler.NotificationFilter() {
 166             @Override
 167             public Optional<DOMNotification> filterNotification(final DOMNotification notification) {
 168                 if (isCapabilityChanged(notification)) {
 169                     LOG.info("{}: Schemas change detected, reconnecting", id);
 170                     // Only disconnect is enough, the reconnecting nature of the connector will take care of reconnecting
 171                     listener.disconnect();
 172                     return Optional.absent();
 173                 }
 174                 return Optional.of(notification);
 175             }
 176
 177             private boolean isCapabilityChanged(final DOMNotification notification) {
 178                 return notification.getBody().getNodeType().equals(NetconfCapabilityChange.QNAME);
 179             }
 180         };
 181
 182         Futures.addCallback(rpcResultListenableFuture, new FutureCallback<DOMRpcResult>() {
 183             @Override
 184             public void onSuccess(final DOMRpcResult domRpcResult) {
 185                 notificationHandler.addNotificationFilter(filter);
 186             }
 187
 188             @Override
 189             public void onFailure(final Throwable t) {
 190                 LOG.warn("Unable to subscribe to base notification stream. Schemas will not be reloaded on the fly", t);
 191             }
 192         });
 193     }
 194
 195     private boolean shouldListenOnSchemaChange(final NetconfSessionPreferences remoteSessionCapabilities) {
 196         return remoteSessionCapabilities.isNotificationsSupported() && reconnectOnSchemasChange;
 197     }
 198
 199     protected void handleSalInitializationSuccess(final SchemaContext result, final NetconfSessionPreferences remoteSessionCapabilities, final DOMRpcService deviceRpc) {
 200         final BaseSchema baseSchema =
 201                 remoteSessionCapabilities.isNotificationsSupported() ?
 202                 BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS :
 203                 BaseSchema.BASE_NETCONF_CTX;
 204         messageTransformer = new NetconfMessageTransformer(result, true, baseSchema);
 205
 206         updateTransformer(messageTransformer);
 207         // salFacade.onDeviceConnected has to be called before the notification handler is initialized
 208         salFacade.onDeviceConnected(result, remoteSessionCapabilities, deviceRpc);
 209         notificationHandler.onRemoteSchemaUp(messageTransformer);
 210
 211         LOG.info("{}: Netconf connector initialized successfully", id);
 212     }
 213
 214     protected void handleSalInitializationFailure(final Throwable t, final RemoteDeviceCommunicator<NetconfMessage> listener) {
 215         LOG.error("{}: Initialization in sal failed, disconnecting from device", id, t);
 216         listener.close();
 217         onRemoteSessionDown();
 218         resetMessageTransformer();
 219     }
 220
 221     /**
 222      * Set the transformer to null as is in initial state
 223      */
 224     private void resetMessageTransformer() {
 225         updateTransformer(null);
 226     }
 227
 228     private void updateTransformer(final MessageTransformer<NetconfMessage> transformer) {
 229         messageTransformer = transformer;
 230     }
 231
 232     private void addProvidedSourcesToSchemaRegistry(final DeviceSources deviceSources) {
 233         final SchemaSourceProvider<YangTextSchemaSource> yangProvider = deviceSources.getSourceProvider();
 234         for (final SourceIdentifier sourceId : deviceSources.getProvidedSources()) {
 235             sourceRegistrations.add(schemaRegistry.registerSchemaSource(yangProvider,
 236                     PotentialSchemaSource.create(sourceId, YangTextSchemaSource.class, PotentialSchemaSource.Costs.REMOTE_IO.getValue())));
 237         }
 238     }
 239
 240     @Override
 241     public void onRemoteSessionDown() {
 242         notificationHandler.onRemoteSchemaDown();
 243
 244         salFacade.onDeviceDisconnected();
 245         for (final SchemaSourceRegistration<? extends SchemaSourceRepresentation> sourceRegistration : sourceRegistrations) {
 246             sourceRegistration.close();
 247         }
 248         resetMessageTransformer();
 249     }
 250
 251     @Override
 252     public void onRemoteSessionFailed(final Throwable throwable) {
 253         salFacade.onDeviceFailed(throwable);
 254     }
 255
 256     @Override
 257     public void onNotification(final NetconfMessage notification) {
 258         notificationHandler.handleNotification(notification);
 259     }
 260
 261     /**
 262      * Just a transfer object containing schema related dependencies. Injected in constructor.
 263      */
 264     public static class SchemaResourcesDTO {
 265         private final SchemaSourceRegistry schemaRegistry;
 266         private final SchemaContextFactory schemaContextFactory;
 267         private final NetconfDeviceSchemasResolver stateSchemasResolver;
 268
 269         public SchemaResourcesDTO(final SchemaSourceRegistry schemaRegistry,
 270                                   final SchemaContextFactory schemaContextFactory,
 271                                   final NetconfDeviceSchemasResolver deviceSchemasResolver) {
 272             this.schemaRegistry = Preconditions.checkNotNull(schemaRegistry);
 273             this.schemaContextFactory = Preconditions.checkNotNull(schemaContextFactory);
 274             this.stateSchemasResolver = Preconditions.checkNotNull(deviceSchemasResolver);
 275         }
 276
 277         public SchemaSourceRegistry getSchemaRegistry() {
 278             return schemaRegistry;
 279         }
 280
 281         public SchemaContextFactory getSchemaContextFactory() {
 282             return schemaContextFactory;
 283         }
 284
 285         public NetconfDeviceSchemasResolver getStateSchemasResolver() {
 286             return stateSchemasResolver;
 287         }
 288     }
 289
 290     /**
 291      * Schema building callable.
 292      */
 293     private static class DeviceSourcesResolver implements Callable<DeviceSources> {
 294
 295         private final NetconfDeviceRpc deviceRpc;
 296         private final NetconfSessionPreferences remoteSessionCapabilities;
 297         private final RemoteDeviceId id;
 298         private final NetconfDeviceSchemasResolver stateSchemasResolver;
 299
 300         DeviceSourcesResolver(final NetconfDeviceRpc deviceRpc, final NetconfSessionPreferences remoteSessionCapabilities,
 301                                      final RemoteDeviceId id, final NetconfDeviceSchemasResolver stateSchemasResolver) {
 302             this.deviceRpc = deviceRpc;
 303             this.remoteSessionCapabilities = remoteSessionCapabilities;
 304             this.id = id;
 305             this.stateSchemasResolver = stateSchemasResolver;
 306         }
 307
 308         public DeviceSourcesResolver(final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceId id, final NetconfDeviceSchemasResolver stateSchemasResolver, final NetconfDeviceRpc rpcForMonitoring) {
 309             this(rpcForMonitoring, remoteSessionCapabilities, id, stateSchemasResolver);
 310         }
 311
 312         @Override
 313         public DeviceSources call() throws Exception {
 314             final NetconfDeviceSchemas availableSchemas = stateSchemasResolver.resolve(deviceRpc, remoteSessionCapabilities, id);
 315             LOG.debug("{}: Schemas exposed by ietf-netconf-monitoring: {}", id, availableSchemas.getAvailableYangSchemasQNames());
 316
 317             final Set<QName> requiredSources = Sets.newHashSet(remoteSessionCapabilities.getModuleBasedCaps());
 318             final Set<QName> providedSources = availableSchemas.getAvailableYangSchemasQNames();
 319
 320             final Set<QName> requiredSourcesNotProvided = Sets.difference(requiredSources, providedSources);
 321             if (!requiredSourcesNotProvided.isEmpty()) {
 322                 LOG.warn("{}: Netconf device does not provide all yang models reported in hello message capabilities, required but not provided: {}",
 323                         id, requiredSourcesNotProvided);
 324                 LOG.warn("{}: Attempting to build schema context from required sources", id);
 325             }
 326
 327             // Here all the sources reported in netconf monitoring are merged with those reported in hello.
 328             // It is necessary to perform this since submodules are not mentioned in hello but still required.
 329             // This clashes with the option of a user to specify supported yang models manually in configuration for netconf-connector
 330             // and as a result one is not able to fully override yang models of a device. It is only possible to add additional models.
 331             final Set<QName> providedSourcesNotRequired = Sets.difference(providedSources, requiredSources);
 332             if (!providedSourcesNotRequired.isEmpty()) {
 333                 LOG.warn("{}: Netconf device provides additional yang models not reported in hello message capabilities: {}",
 334                         id, providedSourcesNotRequired);
 335                 LOG.warn("{}: Adding provided but not required sources as required to prevent failures", id);
 336                 LOG.debug("{}: Netconf device reported in hello: {}", id, requiredSources);
 337                 requiredSources.addAll(providedSourcesNotRequired);
 338             }
 339
 340             final SchemaSourceProvider<YangTextSchemaSource> sourceProvider;
 341             if(availableSchemas instanceof LibraryModulesSchemas) {
 342                 sourceProvider = new YangLibrarySchemaYangSourceProvider(id,
 343                         ((LibraryModulesSchemas) availableSchemas).getAvailableModels());
 344             } else {
 345                 sourceProvider = new NetconfRemoteSchemaYangSourceProvider(id, deviceRpc);
 346             }
 347
 348             return new DeviceSources(requiredSources, providedSources, sourceProvider);
 349         }
 350     }
 351
 352     /**
 353      * Contains RequiredSources - sources from capabilities.
 354      */
 355     private static final class DeviceSources {
 356         private final Set<QName> requiredSources;
 357         private final Set<QName> providedSources;
 358         private final SchemaSourceProvider<YangTextSchemaSource> sourceProvider;
 359
 360         public DeviceSources(final Set<QName> requiredSources, final Set<QName> providedSources,
 361                              final SchemaSourceProvider<YangTextSchemaSource> sourceProvider) {
 362             this.requiredSources = requiredSources;
 363             this.providedSources = providedSources;
 364             this.sourceProvider = sourceProvider;
 365         }
 366
 367         public Set<QName> getRequiredSourcesQName() {
 368             return requiredSources;
 369         }
 370
 371         public Set<QName> getProvidedSourcesQName() {
 372             return providedSources;
 373         }
 374
 375         public Collection<SourceIdentifier> getRequiredSources() {
 376             return Collections2.transform(requiredSources, QNAME_TO_SOURCE_ID_FUNCTION);
 377         }
 378
 379         public Collection<SourceIdentifier> getProvidedSources() {
 380             return Collections2.transform(providedSources, QNAME_TO_SOURCE_ID_FUNCTION);
 381         }
 382
 383         public SchemaSourceProvider<YangTextSchemaSource> getSourceProvider() {
 384             return sourceProvider;
 385         }
 386     }
 387
 388     /**
 389      * Schema builder that tries to build schema context from provided sources or biggest subset of it.
 390      */
 391     private final class SchemaSetup implements Runnable {
 392         private final DeviceSources deviceSources;
 393         private final NetconfSessionPreferences remoteSessionCapabilities;
 394         private final RemoteDeviceCommunicator<NetconfMessage> listener;
 395         private final NetconfDeviceCapabilities capabilities;
 396
 397         public SchemaSetup(final DeviceSources deviceSources, final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceCommunicator<NetconfMessage> listener) {
 398             this.deviceSources = deviceSources;
 399             this.remoteSessionCapabilities = remoteSessionCapabilities;
 400             this.listener = listener;
 401             this.capabilities = remoteSessionCapabilities.getNetconfDeviceCapabilities();
 402         }
 403
 404         @Override
 405         public void run() {
 406             setUpSchema(deviceSources.getRequiredSources());
 407         }
 408
 409         /**
 410          * Build schema context, in case of success or final failure notify device
 411          */
 412         private void setUpSchema(Collection<SourceIdentifier> requiredSources) {
 413             while (!requiredSources.isEmpty()) {
 414                 LOG.trace("{}: Trying to build schema context from {}", id, requiredSources);
 415                 try {
 416                     final CheckedFuture<SchemaContext, SchemaResolutionException> schemaBuilderFuture = schemaContextFactory.createSchemaContext(requiredSources);
 417                     final SchemaContext result = schemaBuilderFuture.checkedGet();
 418                     LOG.debug("{}: Schema context built successfully from {}", id, requiredSources);
 419                     final Collection<QName> filteredQNames = Sets.difference(deviceSources.getRequiredSourcesQName(), capabilities.getUnresolvedCapabilites().keySet());
 420                     capabilities.addCapabilities(filteredQNames);
 421                     capabilities.addNonModuleBasedCapabilities(remoteSessionCapabilities.getNonModuleCaps());
 422                     handleSalInitializationSuccess(result, remoteSessionCapabilities, getDeviceSpecificRpc(result));
 423                     return;
 424                 } catch (final Throwable t) {
 425                     if (t instanceof MissingSchemaSourceException){
 426                         requiredSources = handleMissingSchemaSourceException(requiredSources, (MissingSchemaSourceException) t);
 427                     } else if (t instanceof SchemaResolutionException) {
 428                         // schemaBuilderFuture.checkedGet() throws only SchemaResolutionException
 429                         // that might be wrapping a MissingSchemaSourceException so we need to look
 430                         // at the cause of the exception to make sure we don't misinterpret it.
 431                         if (t.getCause() instanceof MissingSchemaSourceException) {
 432                             requiredSources = handleMissingSchemaSourceException(requiredSources, (MissingSchemaSourceException) t.getCause());
 433                             continue;
 434                         }
 435                         requiredSources = handleSchemaResolutionException(requiredSources, (SchemaResolutionException) t);
 436                     } else {
 437                         // unknown error, fail
 438                         handleSalInitializationFailure(t, listener);
 439                         return;
 440                     }
 441                 }
 442             }
 443             // No more sources, fail
 444             final IllegalStateException cause = new IllegalStateException(id + ": No more sources for schema context");
 445             handleSalInitializationFailure(cause, listener);
 446             salFacade.onDeviceFailed(cause);
 447         }
 448
 449         private Collection<SourceIdentifier> handleMissingSchemaSourceException(final Collection<SourceIdentifier> requiredSources, final MissingSchemaSourceException t) {
 450             // In case source missing, try without it
 451             final SourceIdentifier missingSource = t.getSourceId();
 452             LOG.warn("{}: Unable to build schema context, missing source {}, will reattempt without it", id, missingSource);
 453             LOG.debug("{}: Unable to build schema context, missing source {}, will reattempt without it", t);
 454             final Collection<QName> qNameOfMissingSource = getQNameFromSourceIdentifiers(Sets.newHashSet(missingSource));
 455             if (!qNameOfMissingSource.isEmpty()) {
 456                 capabilities.addUnresolvedCapabilities(qNameOfMissingSource, UnavailableCapability.FailureReason.MissingSource);
 457             }
 458             return stripMissingSource(requiredSources, missingSource);
 459         }
 460
 461         private Collection<SourceIdentifier> handleSchemaResolutionException(final Collection<SourceIdentifier> requiredSources, final SchemaResolutionException resolutionException) {
 462             // In case resolution error, try only with resolved sources
 463             final Set<SourceIdentifier> unresolvedSources = resolutionException.getUnsatisfiedImports().keySet();
 464             capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(unresolvedSources), UnavailableCapability.FailureReason.UnableToResolve);
 465             LOG.warn("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only", id, resolutionException.getUnsatisfiedImports());
 466             LOG.debug("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only", resolutionException);
 467             return resolutionException.getResolvedSources();
 468         }
 469
 470         protected NetconfDeviceRpc getDeviceSpecificRpc(final SchemaContext result) {
 471             return new NetconfDeviceRpc(result, listener, new NetconfMessageTransformer(result, true));
 472         }
 473
 474         private Collection<SourceIdentifier> stripMissingSource(final Collection<SourceIdentifier> requiredSources, final SourceIdentifier sIdToRemove) {
 475             final LinkedList<SourceIdentifier> sourceIdentifiers = Lists.newLinkedList(requiredSources);
 476             final boolean removed = sourceIdentifiers.remove(sIdToRemove);
 477             Preconditions.checkState(removed, "{}: Trying to remove {} from {} failed", id, sIdToRemove, requiredSources);
 478             return sourceIdentifiers;
 479         }
 480
 481         private Collection<QName> getQNameFromSourceIdentifiers(final Collection<SourceIdentifier> identifiers) {
 482             final Collection<QName> qNames = Collections2.transform(identifiers, new Function<SourceIdentifier, QName>() {
 483                 @Override
 484                 public QName apply(final SourceIdentifier sourceIdentifier) {
 485                     return getQNameFromSourceIdentifier(sourceIdentifier);
 486                 }
 487             });
 488
 489             if (qNames.isEmpty()) {
 490                 LOG.debug("{}: Unable to map any source identifiers to a capability reported by device : {}", id, identifiers);
 491             }
 492             return Collections2.filter(qNames, Predicates.notNull());
 493         }
 494
 495         private QName getQNameFromSourceIdentifier(final SourceIdentifier identifier) {
 496             // Required sources are all required and provided merged in DeviceSourcesResolver
 497             for (final QName qname : deviceSources.getRequiredSourcesQName()) {
 498                 if(qname.getLocalName().equals(identifier.getName()) == false) {
 499                     continue;
 500                 }
 501
 502                 if(identifier.getRevision().equals(SourceIdentifier.NOT_PRESENT_FORMATTED_REVISION) &&
 503                         qname.getRevision() == null) {
 504                     return qname;
 505                 }
 506
 507                 if (qname.getFormattedRevision().equals(identifier.getRevision())) {
 508                     return qname;
 509                 }
 510             }
 511             LOG.warn("Unable to map identifier to a devices reported capability: {} Available: {}",identifier, deviceSources.getRequiredSourcesQName());
 512             // return null since we cannot find the QName, this capability will be removed from required sources and not reported as unresolved-capability
 513             return null;
 514         }
 515     }
 516 }