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