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