opendaylight/md-sal/sal-netconf-connector/src/main/java/org/opendaylight/controller/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.controller.sal.connect.netconf;
   9
  10 import com.google.common.annotations.VisibleForTesting;
  11 import com.google.common.base.Function;
  12 import com.google.common.base.Optional;
  13 import com.google.common.base.Preconditions;
  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.HashSet;
  25 import java.util.LinkedList;
  26 import java.util.List;
  27 import java.util.Set;
  28 import java.util.concurrent.Callable;
  29 import java.util.concurrent.ExecutorService;
  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.controller.netconf.api.NetconfMessage;
  34 import org.opendaylight.controller.sal.connect.api.MessageTransformer;
  35 import org.opendaylight.controller.sal.connect.api.RemoteDevice;
  36 import org.opendaylight.controller.sal.connect.api.RemoteDeviceCommunicator;
  37 import org.opendaylight.controller.sal.connect.api.RemoteDeviceHandler;
  38 import org.opendaylight.controller.sal.connect.netconf.listener.NetconfDeviceCapabilities;
  39 import org.opendaylight.controller.sal.connect.netconf.listener.NetconfDeviceCommunicator;
  40 import org.opendaylight.controller.sal.connect.netconf.listener.NetconfSessionPreferences;
  41 import org.opendaylight.controller.sal.connect.netconf.sal.NetconfDeviceRpc;
  42 import org.opendaylight.controller.sal.connect.netconf.schema.NetconfRemoteSchemaYangSourceProvider;
  43 import org.opendaylight.controller.sal.connect.netconf.schema.mapping.NetconfMessageTransformer;
  44 import org.opendaylight.controller.sal.connect.netconf.util.NetconfMessageTransformUtil;
  45 import org.opendaylight.controller.sal.connect.util.RemoteDeviceId;
  46 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.monitoring.extension.rev131210.$YangModuleInfoImpl;
  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.fields.unavailable.capabilities.UnavailableCapability;
  49 import org.opendaylight.yangtools.sal.binding.generator.impl.ModuleInfoBackedContext;
  50 import org.opendaylight.yangtools.yang.common.QName;
  51 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  52 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  53 import org.opendaylight.yangtools.yang.model.repo.api.MissingSchemaSourceException;
  54 import org.opendaylight.yangtools.yang.model.repo.api.SchemaContextFactory;
  55 import org.opendaylight.yangtools.yang.model.repo.api.SchemaResolutionException;
  56 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceRepresentation;
  57 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  58 import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
  59 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
  60 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistration;
  61 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistry;
  62 import org.slf4j.Logger;
  63 import org.slf4j.LoggerFactory;
  64
  65 /**
  66  *  This is a mediator between NetconfDeviceCommunicator and NetconfDeviceSalFacade
  67  */
  68 public final class NetconfDevice implements RemoteDevice<NetconfSessionPreferences, NetconfMessage, NetconfDeviceCommunicator> {
  69
  70     private static final Logger logger = LoggerFactory.getLogger(NetconfDevice.class);
  71
  72     /**
  73      * Initial schema context contains schemas for netconf monitoring and netconf notifications
  74      */
  75     public static final SchemaContext INIT_SCHEMA_CTX;
  76
  77     static {
  78         try {
  79             final ModuleInfoBackedContext moduleInfoBackedContext = ModuleInfoBackedContext.create();
  80             moduleInfoBackedContext.addModuleInfos(
  81                     Lists.newArrayList(
  82                             $YangModuleInfoImpl.getInstance(),
  83                             org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.netconf.notification._1._0.rev080714.$YangModuleInfoImpl.getInstance(),
  84                             org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.netconf.base._1._0.rev110601.$YangModuleInfoImpl.getInstance()));
  85             INIT_SCHEMA_CTX = moduleInfoBackedContext.tryToCreateSchemaContext().get();
  86         } catch (final RuntimeException e) {
  87             logger.error("Unable to prepare schema context for netconf initialization", e);
  88             throw new ExceptionInInitializerError(e);
  89         }
  90     }
  91
  92     public static final Function<QName, SourceIdentifier> QNAME_TO_SOURCE_ID_FUNCTION = new Function<QName, SourceIdentifier>() {
  93         @Override
  94         public SourceIdentifier apply(final QName input) {
  95             return new SourceIdentifier(input.getLocalName(), Optional.fromNullable(input.getFormattedRevision()));
  96         }
  97     };
  98
  99     private final RemoteDeviceId id;
 100     private final boolean reconnectOnSchemasChange;
 101
 102     private final SchemaContextFactory schemaContextFactory;
 103     private final RemoteDeviceHandler<NetconfSessionPreferences> salFacade;
 104     private final ListeningExecutorService processingExecutor;
 105     private final SchemaSourceRegistry schemaRegistry;
 106     private final NetconfStateSchemas.NetconfStateSchemasResolver stateSchemasResolver;
 107     private final NotificationHandler notificationHandler;
 108     private final List<SchemaSourceRegistration<? extends SchemaSourceRepresentation>> sourceRegistrations = Lists.newArrayList();
 109
 110     // Message transformer is constructed once the schemas are available
 111     private MessageTransformer<NetconfMessage> messageTransformer;
 112
 113     public NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id, final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 114                          final ExecutorService globalProcessingExecutor) {
 115         this(schemaResourcesDTO, id, salFacade, globalProcessingExecutor, false);
 116     }
 117
 118     /**
 119      * Create rpc implementation capable of handling RPC for monitoring and notifications even before the schemas of remote device are downloaded
 120      */
 121     static NetconfDeviceRpc getRpcForInitialization(final NetconfDeviceCommunicator listener) {
 122         return new NetconfDeviceRpc(INIT_SCHEMA_CTX, listener, new NetconfMessageTransformer(INIT_SCHEMA_CTX));
 123     }
 124
 125
 126     // FIXME reduce parameters
 127     public NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id, final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 128                          final ExecutorService globalProcessingExecutor, final boolean reconnectOnSchemasChange) {
 129         this.id = id;
 130         this.reconnectOnSchemasChange = reconnectOnSchemasChange;
 131         this.schemaRegistry = schemaResourcesDTO.getSchemaRegistry();
 132         this.schemaContextFactory = schemaResourcesDTO.getSchemaContextFactory();
 133         this.salFacade = salFacade;
 134         this.stateSchemasResolver = schemaResourcesDTO.getStateSchemasResolver();
 135         this.processingExecutor = MoreExecutors.listeningDecorator(globalProcessingExecutor);
 136         this.notificationHandler = new NotificationHandler(salFacade, id);
 137     }
 138
 139     @Override
 140     public void onRemoteSessionUp(final NetconfSessionPreferences remoteSessionCapabilities,
 141                                   final NetconfDeviceCommunicator listener) {
 142         // SchemaContext setup has to be performed in a dedicated thread since
 143         // we are in a netty thread in this method
 144         // Yang models are being downloaded in this method and it would cause a
 145         // deadlock if we used the netty thread
 146         // http://netty.io/wiki/thread-model.html
 147         logger.debug("{}: Session to remote device established with {}", id, remoteSessionCapabilities);
 148
 149         final NetconfDeviceRpc initRpc = getRpcForInitialization(listener);
 150         final DeviceSourcesResolver task = new DeviceSourcesResolver(remoteSessionCapabilities, id, stateSchemasResolver, initRpc);
 151         final ListenableFuture<DeviceSources> sourceResolverFuture = processingExecutor.submit(task);
 152
 153         if(shouldListenOnSchemaChange(remoteSessionCapabilities)) {
 154            registerToBaseNetconfStream(initRpc, listener);
 155         }
 156
 157         final FutureCallback<DeviceSources> resolvedSourceCallback = new FutureCallback<DeviceSources>() {
 158             @Override
 159             public void onSuccess(final DeviceSources result) {
 160                 addProvidedSourcesToSchemaRegistry(initRpc, result);
 161                 setUpSchema(result);
 162             }
 163
 164             private void setUpSchema(final DeviceSources result) {
 165                 processingExecutor.submit(new RecursiveSchemaSetup(result, remoteSessionCapabilities, listener));
 166             }
 167
 168             @Override
 169             public void onFailure(final Throwable t) {
 170                 logger.warn("{}: Unexpected error resolving device sources: {}", id, t);
 171                 handleSalInitializationFailure(t, listener);
 172             }
 173         };
 174
 175         Futures.addCallback(sourceResolverFuture, resolvedSourceCallback);
 176     }
 177
 178     private void registerToBaseNetconfStream(final NetconfDeviceRpc deviceRpc, final NetconfDeviceCommunicator listener) {
 179        final CheckedFuture<DOMRpcResult, DOMRpcException> rpcResultListenableFuture =
 180                 deviceRpc.invokeRpc(NetconfMessageTransformUtil.toPath(NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_QNAME), NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_CONTENT);
 181
 182         final NotificationHandler.NotificationFilter filter = new NotificationHandler.NotificationFilter() {
 183             @Override
 184             public Optional<NormalizedNode<?, ?>> filterNotification(final NormalizedNode<?, ?> notification) {
 185                 if (isCapabilityChanged(notification)) {
 186                     logger.info("{}: Schemas change detected, reconnecting", id);
 187                     // Only disconnect is enough, the reconnecting nature of the connector will take care of reconnecting
 188                     listener.disconnect();
 189                     return Optional.absent();
 190                 }
 191                 return Optional.<NormalizedNode<?, ?>>of(notification);
 192             }
 193
 194             private boolean isCapabilityChanged(final NormalizedNode<?, ?> notification) {
 195                 return notification.getNodeType().equals(NetconfCapabilityChange.QNAME);
 196             }
 197         };
 198
 199         Futures.addCallback(rpcResultListenableFuture, new FutureCallback<DOMRpcResult>() {
 200             @Override
 201             public void onSuccess(final DOMRpcResult domRpcResult) {
 202                 notificationHandler.addNotificationFilter(filter);
 203             }
 204
 205             @Override
 206             public void onFailure(final Throwable t) {
 207                 logger.warn("Unable to subscribe to base notification stream. Schemas will not be reloaded on the fly", t);
 208             }
 209         });
 210     }
 211
 212     private boolean shouldListenOnSchemaChange(final NetconfSessionPreferences remoteSessionCapabilities) {
 213         return remoteSessionCapabilities.isNotificationsSupported() && reconnectOnSchemasChange;
 214     }
 215
 216     @VisibleForTesting
 217     void handleSalInitializationSuccess(final SchemaContext result, final NetconfSessionPreferences remoteSessionCapabilities, final DOMRpcService deviceRpc) {
 218         messageTransformer = new NetconfMessageTransformer(result);
 219
 220         updateTransformer(messageTransformer);
 221         notificationHandler.onRemoteSchemaUp(messageTransformer);
 222         salFacade.onDeviceConnected(result, remoteSessionCapabilities, deviceRpc);
 223
 224         logger.info("{}: Netconf connector initialized successfully", id);
 225     }
 226
 227     private void handleSalInitializationFailure(final Throwable t, final RemoteDeviceCommunicator<NetconfMessage> listener) {
 228         logger.error("{}: Initialization in sal failed, disconnecting from device", id, t);
 229         listener.close();
 230         onRemoteSessionDown();
 231         resetMessageTransformer();
 232     }
 233
 234     /**
 235      * Set the transformer to null as is in initial state
 236      */
 237     private void resetMessageTransformer() {
 238         updateTransformer(null);
 239     }
 240
 241     private void updateTransformer(final MessageTransformer<NetconfMessage> transformer) {
 242         messageTransformer = transformer;
 243     }
 244
 245     private void addProvidedSourcesToSchemaRegistry(final NetconfDeviceRpc deviceRpc, final DeviceSources deviceSources) {
 246         final NetconfRemoteSchemaYangSourceProvider yangProvider = new NetconfRemoteSchemaYangSourceProvider(id, deviceRpc);
 247         for (final SourceIdentifier sourceId : deviceSources.getProvidedSources()) {
 248             sourceRegistrations.add(schemaRegistry.registerSchemaSource(yangProvider,
 249                     PotentialSchemaSource.create(sourceId, YangTextSchemaSource.class, PotentialSchemaSource.Costs.REMOTE_IO.getValue())));
 250         }
 251     }
 252
 253     @Override
 254     public void onRemoteSessionDown() {
 255         notificationHandler.onRemoteSchemaDown();
 256
 257         salFacade.onDeviceDisconnected();
 258         for (final SchemaSourceRegistration<? extends SchemaSourceRepresentation> sourceRegistration : sourceRegistrations) {
 259             sourceRegistration.close();
 260         }
 261         resetMessageTransformer();
 262     }
 263
 264     @Override
 265     public void onRemoteSessionFailed(final Throwable throwable) {
 266         salFacade.onDeviceFailed(throwable);
 267     }
 268
 269     @Override
 270     public void onNotification(final NetconfMessage notification) {
 271         notificationHandler.handleNotification(notification);
 272     }
 273
 274     /**
 275      * Just a transfer object containing schema related dependencies. Injected in constructor.
 276      */
 277     public static class SchemaResourcesDTO {
 278         private final SchemaSourceRegistry schemaRegistry;
 279         private final SchemaContextFactory schemaContextFactory;
 280         private final NetconfStateSchemas.NetconfStateSchemasResolver stateSchemasResolver;
 281
 282         public SchemaResourcesDTO(final SchemaSourceRegistry schemaRegistry, final SchemaContextFactory schemaContextFactory, final NetconfStateSchemas.NetconfStateSchemasResolver stateSchemasResolver) {
 283             this.schemaRegistry = Preconditions.checkNotNull(schemaRegistry);
 284             this.schemaContextFactory = Preconditions.checkNotNull(schemaContextFactory);
 285             this.stateSchemasResolver = Preconditions.checkNotNull(stateSchemasResolver);
 286         }
 287
 288         public SchemaSourceRegistry getSchemaRegistry() {
 289             return schemaRegistry;
 290         }
 291
 292         public SchemaContextFactory getSchemaContextFactory() {
 293             return schemaContextFactory;
 294         }
 295
 296         public NetconfStateSchemas.NetconfStateSchemasResolver getStateSchemasResolver() {
 297             return stateSchemasResolver;
 298         }
 299     }
 300
 301     /**
 302      * Schema building callable.
 303      */
 304     private static class DeviceSourcesResolver implements Callable<DeviceSources> {
 305
 306         private final NetconfDeviceRpc deviceRpc;
 307         private final NetconfSessionPreferences remoteSessionCapabilities;
 308         private final RemoteDeviceId id;
 309         private final NetconfStateSchemas.NetconfStateSchemasResolver stateSchemasResolver;
 310
 311         DeviceSourcesResolver(final NetconfDeviceRpc deviceRpc, final NetconfSessionPreferences remoteSessionCapabilities,
 312                                      final RemoteDeviceId id, final NetconfStateSchemas.NetconfStateSchemasResolver stateSchemasResolver) {
 313             this.deviceRpc = deviceRpc;
 314             this.remoteSessionCapabilities = remoteSessionCapabilities;
 315             this.id = id;
 316             this.stateSchemasResolver = stateSchemasResolver;
 317         }
 318
 319         public DeviceSourcesResolver(final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceId id, final NetconfStateSchemas.NetconfStateSchemasResolver stateSchemasResolver, final NetconfDeviceRpc rpcForMonitoring) {
 320             this(rpcForMonitoring, remoteSessionCapabilities, id, stateSchemasResolver);
 321         }
 322
 323         @Override
 324         public DeviceSources call() throws Exception {
 325
 326             final Set<SourceIdentifier> requiredSources = Sets.newHashSet(Collections2.transform(
 327                     remoteSessionCapabilities.getModuleBasedCaps(), QNAME_TO_SOURCE_ID_FUNCTION));
 328
 329             // If monitoring is not supported, we will still attempt to create schema, sources might be already provided
 330             final NetconfStateSchemas availableSchemas = stateSchemasResolver.resolve(deviceRpc, remoteSessionCapabilities, id);
 331             logger.debug("{}: Schemas exposed by ietf-netconf-monitoring: {}", id, availableSchemas.getAvailableYangSchemasQNames());
 332
 333             final Set<SourceIdentifier> providedSources = Sets.newHashSet(Collections2.transform(
 334                     availableSchemas.getAvailableYangSchemasQNames(), QNAME_TO_SOURCE_ID_FUNCTION));
 335
 336             final Set<SourceIdentifier> requiredSourcesNotProvided = Sets.difference(requiredSources, providedSources);
 337
 338             if (!requiredSourcesNotProvided.isEmpty()) {
 339                 logger.warn("{}: Netconf device does not provide all yang models reported in hello message capabilities, required but not provided: {}",
 340                         id, requiredSourcesNotProvided);
 341                 logger.warn("{}: Attempting to build schema context from required sources", id);
 342             }
 343
 344
 345             // Here all the sources reported in netconf monitoring are merged with those reported in hello.
 346             // It is necessary to perform this since submodules are not mentioned in hello but still required.
 347             // This clashes with the option of a user to specify supported yang models manually in configuration for netconf-connector
 348             // and as a result one is not able to fully override yang models of a device. It is only possible to add additional models.
 349             final Set<SourceIdentifier> providedSourcesNotRequired = Sets.difference(providedSources, requiredSources);
 350             if (!providedSourcesNotRequired.isEmpty()) {
 351                 logger.warn("{}: Netconf device provides additional yang models not reported in hello message capabilities: {}",
 352                         id, providedSourcesNotRequired);
 353                 logger.warn("{}: Adding provided but not required sources as required to prevent failures", id);
 354                 logger.debug("{}: Netconf device reported in hello: {}", id, requiredSources);
 355                 requiredSources.addAll(providedSourcesNotRequired);
 356             }
 357
 358             return new DeviceSources(requiredSources, providedSources);
 359         }
 360     }
 361
 362     /**
 363      * Contains RequiredSources - sources from capabilities.
 364      */
 365     private static final class DeviceSources {
 366         private final Collection<SourceIdentifier> requiredSources;
 367         private final Collection<SourceIdentifier> providedSources;
 368
 369         public DeviceSources(final Collection<SourceIdentifier> requiredSources, final Collection<SourceIdentifier> providedSources) {
 370             this.requiredSources = requiredSources;
 371             this.providedSources = providedSources;
 372         }
 373
 374         public Collection<SourceIdentifier> getRequiredSources() {
 375             return requiredSources;
 376         }
 377
 378         public Collection<SourceIdentifier> getProvidedSources() {
 379             return providedSources;
 380         }
 381
 382     }
 383
 384     /**
 385      * Schema builder that tries to build schema context from provided sources or biggest subset of it.
 386      */
 387     private final class RecursiveSchemaSetup implements Runnable {
 388         private final DeviceSources deviceSources;
 389         private final NetconfSessionPreferences remoteSessionCapabilities;
 390         private final RemoteDeviceCommunicator<NetconfMessage> listener;
 391         private final NetconfDeviceCapabilities capabilities;
 392
 393         public RecursiveSchemaSetup(final DeviceSources deviceSources, final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceCommunicator<NetconfMessage> listener) {
 394             this.deviceSources = deviceSources;
 395             this.remoteSessionCapabilities = remoteSessionCapabilities;
 396             this.listener = listener;
 397             this.capabilities = remoteSessionCapabilities.getNetconfDeviceCapabilities();
 398         }
 399
 400         @Override
 401         public void run() {
 402             setUpSchema(deviceSources.getRequiredSources());
 403         }
 404
 405         /**
 406          * Recursively build schema context, in case of success or final failure notify device
 407          */
 408         // FIXME reimplement without recursion
 409         private void setUpSchema(final Collection<SourceIdentifier> requiredSources) {
 410             logger.trace("{}: Trying to build schema context from {}", id, requiredSources);
 411
 412             // If no more sources, fail
 413             if(requiredSources.isEmpty()) {
 414                 handleSalInitializationFailure(new IllegalStateException(id + ": No more sources for schema context"), listener);
 415                 return;
 416             }
 417
 418             final CheckedFuture<SchemaContext, SchemaResolutionException> schemaBuilderFuture = schemaContextFactory.createSchemaContext(requiredSources);
 419
 420             final FutureCallback<SchemaContext> RecursiveSchemaBuilderCallback = new FutureCallback<SchemaContext>() {
 421
 422                 @Override
 423                 public void onSuccess(final SchemaContext result) {
 424                     logger.debug("{}: Schema context built successfully from {}", id, requiredSources);
 425                     final Collection<QName> filteredQNames = Sets.difference(remoteSessionCapabilities.getModuleBasedCaps(), capabilities.getUnresolvedCapabilites().keySet());
 426                     capabilities.addCapabilities(filteredQNames);
 427                     capabilities.addNonModuleBasedCapabilities(remoteSessionCapabilities.getNonModuleCaps());
 428                     handleSalInitializationSuccess(result, remoteSessionCapabilities, getDeviceSpecificRpc(result));
 429                 }
 430
 431                 @Override
 432                 public void onFailure(final Throwable t) {
 433                     // In case source missing, try without it
 434                     if (t instanceof MissingSchemaSourceException) {
 435                         final SourceIdentifier missingSource = ((MissingSchemaSourceException) t).getSourceId();
 436                         logger.warn("{}: Unable to build schema context, missing source {}, will reattempt without it", id, missingSource);
 437                         capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(Sets.newHashSet(missingSource)), UnavailableCapability.FailureReason.MissingSource);
 438                         setUpSchema(stripMissingSource(requiredSources, missingSource));
 439
 440                     // In case resolution error, try only with resolved sources
 441                     } else if (t instanceof SchemaResolutionException) {
 442                         // TODO check for infinite loop
 443                         final SchemaResolutionException resolutionException = (SchemaResolutionException) t;
 444                         final Set<SourceIdentifier> unresolvedSources = resolutionException.getUnsatisfiedImports().keySet();
 445                         capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(unresolvedSources), UnavailableCapability.FailureReason.UnableToResolve);
 446                         logger.warn("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only", id, resolutionException.getUnsatisfiedImports());
 447                         setUpSchema(resolutionException.getResolvedSources());
 448                     // unknown error, fail
 449                     } else {
 450                         handleSalInitializationFailure(t, listener);
 451                     }
 452                 }
 453             };
 454
 455             Futures.addCallback(schemaBuilderFuture, RecursiveSchemaBuilderCallback);
 456         }
 457
 458         private NetconfDeviceRpc getDeviceSpecificRpc(final SchemaContext result) {
 459             return new NetconfDeviceRpc(result, listener, new NetconfMessageTransformer(result));
 460         }
 461
 462         private Collection<SourceIdentifier> stripMissingSource(final Collection<SourceIdentifier> requiredSources, final SourceIdentifier sIdToRemove) {
 463             final LinkedList<SourceIdentifier> sourceIdentifiers = Lists.newLinkedList(requiredSources);
 464             final boolean removed = sourceIdentifiers.remove(sIdToRemove);
 465             Preconditions.checkState(removed, "{}: Trying to remove {} from {} failed", id, sIdToRemove, requiredSources);
 466             return sourceIdentifiers;
 467         }
 468
 469         private Collection<QName> getQNameFromSourceIdentifiers(final Collection<SourceIdentifier> identifiers) {
 470             final Collection<QName> qNames = new HashSet<>();
 471             for (final SourceIdentifier source : identifiers) {
 472                 final Optional<QName> qname = getQNameFromSourceIdentifier(source);
 473                 if (qname.isPresent()) {
 474                     qNames.add(qname.get());
 475                 }
 476             }
 477             if (qNames.isEmpty()) {
 478                 logger.debug("Unable to map any source identfiers to a capability reported by device : " + identifiers);
 479             }
 480             return qNames;
 481         }
 482
 483         private Optional<QName> getQNameFromSourceIdentifier(final SourceIdentifier identifier) {
 484             for (final QName qname : remoteSessionCapabilities.getModuleBasedCaps()) {
 485                 if (qname.getLocalName().equals(identifier.getName())
 486                         && qname.getFormattedRevision().equals(identifier.getRevision())) {
 487                     return Optional.of(qname);
 488                 }
 489             }
 490             throw new IllegalArgumentException("Unable to map identifier to a devices reported capability: " + identifier);
 491         }
 492     }
 493 }