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.Collections;
  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 java.util.stream.Collectors;
  31 import org.opendaylight.controller.md.sal.dom.api.DOMNotification;
  32 import org.opendaylight.controller.md.sal.dom.api.DOMRpcException;
  33 import org.opendaylight.controller.md.sal.dom.api.DOMRpcResult;
  34 import org.opendaylight.controller.md.sal.dom.api.DOMRpcService;
  35 import org.opendaylight.netconf.api.NetconfMessage;
  36 import org.opendaylight.netconf.sal.connect.api.MessageTransformer;
  37 import org.opendaylight.netconf.sal.connect.api.NetconfDeviceSchemas;
  38 import org.opendaylight.netconf.sal.connect.api.NetconfDeviceSchemasResolver;
  39 import org.opendaylight.netconf.sal.connect.api.RemoteDevice;
  40 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceCommunicator;
  41 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceHandler;
  42 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCapabilities;
  43 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCommunicator;
  44 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfSessionPreferences;
  45 import org.opendaylight.netconf.sal.connect.netconf.sal.NetconfDeviceRpc;
  46 import org.opendaylight.netconf.sal.connect.netconf.schema.NetconfRemoteSchemaYangSourceProvider;
  47 import org.opendaylight.netconf.sal.connect.netconf.schema.YangLibrarySchemaYangSourceProvider;
  48 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.BaseSchema;
  49 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.NetconfMessageTransformer;
  50 import org.opendaylight.netconf.sal.connect.netconf.util.NetconfMessageTransformUtil;
  51 import org.opendaylight.netconf.sal.connect.util.RemoteDeviceId;
  52 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.notifications.rev120206.NetconfCapabilityChange;
  53 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.available.capabilities.AvailableCapability;
  54 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.available.capabilities.AvailableCapabilityBuilder;
  55 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.unavailable.capabilities.UnavailableCapability;
  56 import org.opendaylight.yangtools.yang.common.QName;
  57 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  58 import org.opendaylight.yangtools.yang.model.repo.api.MissingSchemaSourceException;
  59 import org.opendaylight.yangtools.yang.model.repo.api.RevisionSourceIdentifier;
  60 import org.opendaylight.yangtools.yang.model.repo.api.SchemaContextFactory;
  61 import org.opendaylight.yangtools.yang.model.repo.api.SchemaRepository;
  62 import org.opendaylight.yangtools.yang.model.repo.api.SchemaResolutionException;
  63 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceException;
  64 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceRepresentation;
  65 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  66 import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
  67 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
  68 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
  69 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistration;
  70 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistry;
  71 import org.opendaylight.yangtools.yang.parser.util.ASTSchemaSource;
  72 import org.slf4j.Logger;
  73 import org.slf4j.LoggerFactory;
  74
  75 /**
  76  *  This is a mediator between NetconfDeviceCommunicator and NetconfDeviceSalFacade
  77  */
  78 public class NetconfDevice implements RemoteDevice<NetconfSessionPreferences, NetconfMessage, NetconfDeviceCommunicator> {
  79
  80     private static final Logger LOG = LoggerFactory.getLogger(NetconfDevice.class);
  81
  82     public static final Function<QName, SourceIdentifier> QNAME_TO_SOURCE_ID_FUNCTION = new Function<QName, SourceIdentifier>() {
  83         @Override
  84         public SourceIdentifier apply(final QName input) {
  85             return RevisionSourceIdentifier
  86                     .create(input.getLocalName(), Optional.fromNullable(input.getFormattedRevision()));
  87         }
  88     };
  89
  90     protected final RemoteDeviceId id;
  91     private final boolean reconnectOnSchemasChange;
  92
  93     protected final SchemaContextFactory schemaContextFactory;
  94     private final RemoteDeviceHandler<NetconfSessionPreferences> salFacade;
  95     private final ListeningExecutorService processingExecutor;
  96     protected final SchemaSourceRegistry schemaRegistry;
  97     protected final SchemaRepository schemaRepository;
  98     private final NetconfDeviceSchemasResolver stateSchemasResolver;
  99     private final NotificationHandler notificationHandler;
 100     protected final List<SchemaSourceRegistration<? extends SchemaSourceRepresentation>> sourceRegistrations = Lists.newArrayList();
 101
 102     // Message transformer is constructed once the schemas are available
 103     private MessageTransformer<NetconfMessage> messageTransformer;
 104
 105     /**
 106      * Create rpc implementation capable of handling RPC for monitoring and notifications even before the schemas of remote device are downloaded
 107      */
 108     static NetconfDeviceRpc getRpcForInitialization(final NetconfDeviceCommunicator listener, final boolean notificationSupport) {
 109         final BaseSchema baseSchema = notificationSupport ?
 110                 BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS :
 111                 BaseSchema.BASE_NETCONF_CTX;
 112
 113         return new NetconfDeviceRpc(baseSchema.getSchemaContext(), listener, new NetconfMessageTransformer(baseSchema.getSchemaContext(), false, baseSchema));
 114     }
 115
 116     public NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id, final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 117                          final ExecutorService globalProcessingExecutor, final boolean reconnectOnSchemasChange) {
 118         this.id = id;
 119         this.reconnectOnSchemasChange = reconnectOnSchemasChange;
 120         this.schemaRegistry = schemaResourcesDTO.getSchemaRegistry();
 121         this.schemaRepository = schemaResourcesDTO.getSchemaRepository();
 122         this.schemaContextFactory = schemaResourcesDTO.getSchemaContextFactory();
 123         this.salFacade = salFacade;
 124         this.stateSchemasResolver = schemaResourcesDTO.getStateSchemasResolver();
 125         this.processingExecutor = MoreExecutors.listeningDecorator(globalProcessingExecutor);
 126         this.notificationHandler = new NotificationHandler(salFacade, id);
 127     }
 128
 129     @Override
 130     public void onRemoteSessionUp(final NetconfSessionPreferences remoteSessionCapabilities,
 131                                   final NetconfDeviceCommunicator listener) {
 132         // SchemaContext setup has to be performed in a dedicated thread since
 133         // we are in a netty thread in this method
 134         // Yang models are being downloaded in this method and it would cause a
 135         // deadlock if we used the netty thread
 136         // http://netty.io/wiki/thread-model.html
 137         LOG.debug("{}: Session to remote device established with {}", id, remoteSessionCapabilities);
 138
 139         final NetconfDeviceRpc initRpc = getRpcForInitialization(listener, remoteSessionCapabilities.isNotificationsSupported());
 140         final DeviceSourcesResolver task = new DeviceSourcesResolver(remoteSessionCapabilities, id, stateSchemasResolver, initRpc);
 141         final ListenableFuture<DeviceSources> sourceResolverFuture = processingExecutor.submit(task);
 142
 143         if (shouldListenOnSchemaChange(remoteSessionCapabilities)) {
 144             registerToBaseNetconfStream(initRpc, listener);
 145         }
 146
 147         final FutureCallback<DeviceSources> resolvedSourceCallback = new FutureCallback<DeviceSources>() {
 148             @Override
 149             public void onSuccess(final DeviceSources result) {
 150                 addProvidedSourcesToSchemaRegistry(result);
 151                 setUpSchema(result);
 152             }
 153
 154             private void setUpSchema(final DeviceSources result) {
 155                 processingExecutor.submit(new SchemaSetup(result, remoteSessionCapabilities, listener));
 156             }
 157
 158             @Override
 159             public void onFailure(final Throwable t) {
 160                 LOG.warn("{}: Unexpected error resolving device sources: {}", id, t);
 161                 handleSalInitializationFailure(t, listener);
 162             }
 163         };
 164
 165         Futures.addCallback(sourceResolverFuture, resolvedSourceCallback);
 166     }
 167
 168     private void registerToBaseNetconfStream(final NetconfDeviceRpc deviceRpc, final NetconfDeviceCommunicator listener) {
 169        // TODO check whether the model describing create subscription is present in schema
 170         // 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)
 171         final CheckedFuture<DOMRpcResult, DOMRpcException> rpcResultListenableFuture =
 172                 deviceRpc.invokeRpc(NetconfMessageTransformUtil.toPath(NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_QNAME), NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_CONTENT);
 173
 174         final NotificationHandler.NotificationFilter filter = new NotificationHandler.NotificationFilter() {
 175             @Override
 176             public Optional<DOMNotification> filterNotification(final DOMNotification notification) {
 177                 if (isCapabilityChanged(notification)) {
 178                     LOG.info("{}: Schemas change detected, reconnecting", id);
 179                     // Only disconnect is enough, the reconnecting nature of the connector will take care of reconnecting
 180                     listener.disconnect();
 181                     return Optional.absent();
 182                 }
 183                 return Optional.of(notification);
 184             }
 185
 186             private boolean isCapabilityChanged(final DOMNotification notification) {
 187                 return notification.getBody().getNodeType().equals(NetconfCapabilityChange.QNAME);
 188             }
 189         };
 190
 191         Futures.addCallback(rpcResultListenableFuture, new FutureCallback<DOMRpcResult>() {
 192             @Override
 193             public void onSuccess(final DOMRpcResult domRpcResult) {
 194                 notificationHandler.addNotificationFilter(filter);
 195             }
 196
 197             @Override
 198             public void onFailure(final Throwable t) {
 199                 LOG.warn("Unable to subscribe to base notification stream. Schemas will not be reloaded on the fly", t);
 200             }
 201         });
 202     }
 203
 204     private boolean shouldListenOnSchemaChange(final NetconfSessionPreferences remoteSessionCapabilities) {
 205         return remoteSessionCapabilities.isNotificationsSupported() && reconnectOnSchemasChange;
 206     }
 207
 208     void handleSalInitializationSuccess(final SchemaContext result, final NetconfSessionPreferences remoteSessionCapabilities, final DOMRpcService deviceRpc) {
 209         final BaseSchema baseSchema =
 210                 remoteSessionCapabilities.isNotificationsSupported() ?
 211                 BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS :
 212                 BaseSchema.BASE_NETCONF_CTX;
 213         messageTransformer = new NetconfMessageTransformer(result, true, baseSchema);
 214
 215         updateTransformer(messageTransformer);
 216         // salFacade.onDeviceConnected has to be called before the notification handler is initialized
 217         salFacade.onDeviceConnected(result, remoteSessionCapabilities, deviceRpc);
 218         notificationHandler.onRemoteSchemaUp(messageTransformer);
 219
 220         LOG.info("{}: Netconf connector initialized successfully", id);
 221     }
 222
 223     void handleSalInitializationFailure(final Throwable t, final RemoteDeviceCommunicator<NetconfMessage> listener) {
 224         LOG.error("{}: Initialization in sal failed, disconnecting from device", id, t);
 225         listener.close();
 226         onRemoteSessionDown();
 227         resetMessageTransformer();
 228     }
 229
 230     /**
 231      * Set the transformer to null as is in initial state
 232      */
 233     private void resetMessageTransformer() {
 234         updateTransformer(null);
 235     }
 236
 237     private void updateTransformer(final MessageTransformer<NetconfMessage> transformer) {
 238         messageTransformer = transformer;
 239     }
 240
 241     private void addProvidedSourcesToSchemaRegistry(final DeviceSources deviceSources) {
 242         final SchemaSourceProvider<YangTextSchemaSource> yangProvider = deviceSources.getSourceProvider();
 243         for (final SourceIdentifier sourceId : deviceSources.getProvidedSources()) {
 244             sourceRegistrations.add(schemaRegistry.registerSchemaSource(yangProvider,
 245                     PotentialSchemaSource.create(sourceId, YangTextSchemaSource.class, PotentialSchemaSource.Costs.REMOTE_IO.getValue())));
 246         }
 247     }
 248
 249     @Override
 250     public void onRemoteSessionDown() {
 251         notificationHandler.onRemoteSchemaDown();
 252
 253         salFacade.onDeviceDisconnected();
 254         for (final SchemaSourceRegistration<? extends SchemaSourceRepresentation> sourceRegistration : sourceRegistrations) {
 255             sourceRegistration.close();
 256         }
 257         resetMessageTransformer();
 258     }
 259
 260     @Override
 261     public void onRemoteSessionFailed(final Throwable throwable) {
 262         salFacade.onDeviceFailed(throwable);
 263     }
 264
 265     @Override
 266     public void onNotification(final NetconfMessage notification) {
 267         notificationHandler.handleNotification(notification);
 268     }
 269
 270     /**
 271      * Just a transfer object containing schema related dependencies. Injected in constructor.
 272      */
 273     public static class SchemaResourcesDTO {
 274         private final SchemaSourceRegistry schemaRegistry;
 275         private final SchemaRepository schemaRepository;
 276         private final SchemaContextFactory schemaContextFactory;
 277         private final NetconfDeviceSchemasResolver stateSchemasResolver;
 278
 279         public SchemaResourcesDTO(final SchemaSourceRegistry schemaRegistry,
 280                                   final SchemaRepository schemaRepository,
 281                                   final SchemaContextFactory schemaContextFactory,
 282                                   final NetconfDeviceSchemasResolver deviceSchemasResolver) {
 283             this.schemaRegistry = Preconditions.checkNotNull(schemaRegistry);
 284             this.schemaRepository = Preconditions.checkNotNull(schemaRepository);
 285             this.schemaContextFactory = Preconditions.checkNotNull(schemaContextFactory);
 286             this.stateSchemasResolver = Preconditions.checkNotNull(deviceSchemasResolver);
 287         }
 288
 289         public SchemaSourceRegistry getSchemaRegistry() {
 290             return schemaRegistry;
 291         }
 292
 293         public SchemaRepository getSchemaRepository() {
 294             return schemaRepository;
 295         }
 296
 297         public SchemaContextFactory getSchemaContextFactory() {
 298             return schemaContextFactory;
 299         }
 300
 301         public NetconfDeviceSchemasResolver getStateSchemasResolver() {
 302             return stateSchemasResolver;
 303         }
 304     }
 305
 306     /**
 307      * Schema building callable.
 308      */
 309     private static class DeviceSourcesResolver implements Callable<DeviceSources> {
 310
 311         private final NetconfDeviceRpc deviceRpc;
 312         private final NetconfSessionPreferences remoteSessionCapabilities;
 313         private final RemoteDeviceId id;
 314         private final NetconfDeviceSchemasResolver stateSchemasResolver;
 315
 316         DeviceSourcesResolver(final NetconfDeviceRpc deviceRpc, final NetconfSessionPreferences remoteSessionCapabilities,
 317                                      final RemoteDeviceId id, final NetconfDeviceSchemasResolver stateSchemasResolver) {
 318             this.deviceRpc = deviceRpc;
 319             this.remoteSessionCapabilities = remoteSessionCapabilities;
 320             this.id = id;
 321             this.stateSchemasResolver = stateSchemasResolver;
 322         }
 323
 324         public DeviceSourcesResolver(final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceId id, final NetconfDeviceSchemasResolver stateSchemasResolver, final NetconfDeviceRpc rpcForMonitoring) {
 325             this(rpcForMonitoring, remoteSessionCapabilities, id, stateSchemasResolver);
 326         }
 327
 328         @Override
 329         public DeviceSources call() throws Exception {
 330             final NetconfDeviceSchemas availableSchemas = stateSchemasResolver.resolve(deviceRpc, remoteSessionCapabilities, id);
 331             LOG.debug("{}: Schemas exposed by ietf-netconf-monitoring: {}", id, availableSchemas.getAvailableYangSchemasQNames());
 332
 333             final Set<QName> requiredSources = Sets.newHashSet(remoteSessionCapabilities.getModuleBasedCaps());
 334             final Set<QName> providedSources = availableSchemas.getAvailableYangSchemasQNames();
 335
 336             final Set<QName> requiredSourcesNotProvided = Sets.difference(requiredSources, providedSources);
 337             if (!requiredSourcesNotProvided.isEmpty()) {
 338                 LOG.warn("{}: Netconf device does not provide all yang models reported in hello message capabilities, required but not provided: {}",
 339                         id, requiredSourcesNotProvided);
 340                 LOG.warn("{}: Attempting to build schema context from required sources", id);
 341             }
 342
 343             // Here all the sources reported in netconf monitoring are merged with those reported in hello.
 344             // It is necessary to perform this since submodules are not mentioned in hello but still required.
 345             // This clashes with the option of a user to specify supported yang models manually in configuration for netconf-connector
 346             // and as a result one is not able to fully override yang models of a device. It is only possible to add additional models.
 347             final Set<QName> providedSourcesNotRequired = Sets.difference(providedSources, requiredSources);
 348             if (!providedSourcesNotRequired.isEmpty()) {
 349                 LOG.warn("{}: Netconf device provides additional yang models not reported in hello message capabilities: {}",
 350                         id, providedSourcesNotRequired);
 351                 LOG.warn("{}: Adding provided but not required sources as required to prevent failures", id);
 352                 LOG.debug("{}: Netconf device reported in hello: {}", id, requiredSources);
 353                 requiredSources.addAll(providedSourcesNotRequired);
 354             }
 355
 356             final SchemaSourceProvider<YangTextSchemaSource> sourceProvider;
 357             if(availableSchemas instanceof LibraryModulesSchemas) {
 358                 sourceProvider = new YangLibrarySchemaYangSourceProvider(id,
 359                         ((LibraryModulesSchemas) availableSchemas).getAvailableModels());
 360             } else {
 361                 sourceProvider = new NetconfRemoteSchemaYangSourceProvider(id, deviceRpc);
 362             }
 363
 364             return new DeviceSources(requiredSources, providedSources, sourceProvider);
 365         }
 366     }
 367
 368     /**
 369      * Contains RequiredSources - sources from capabilities.
 370      */
 371     private static final class DeviceSources {
 372         private final Set<QName> requiredSources;
 373         private final Set<QName> providedSources;
 374         private final SchemaSourceProvider<YangTextSchemaSource> sourceProvider;
 375
 376         public DeviceSources(final Set<QName> requiredSources, final Set<QName> providedSources,
 377                              final SchemaSourceProvider<YangTextSchemaSource> sourceProvider) {
 378             this.requiredSources = requiredSources;
 379             this.providedSources = providedSources;
 380             this.sourceProvider = sourceProvider;
 381         }
 382
 383         public Set<QName> getRequiredSourcesQName() {
 384             return requiredSources;
 385         }
 386
 387         public Set<QName> getProvidedSourcesQName() {
 388             return providedSources;
 389         }
 390
 391         public Collection<SourceIdentifier> getRequiredSources() {
 392             return Collections2.transform(requiredSources, QNAME_TO_SOURCE_ID_FUNCTION);
 393         }
 394
 395         public Collection<SourceIdentifier> getProvidedSources() {
 396             return Collections2.transform(providedSources, QNAME_TO_SOURCE_ID_FUNCTION);
 397         }
 398
 399         public SchemaSourceProvider<YangTextSchemaSource> getSourceProvider() {
 400             return sourceProvider;
 401         }
 402     }
 403
 404     /**
 405      * Schema builder that tries to build schema context from provided sources or biggest subset of it.
 406      */
 407     private final class SchemaSetup implements Runnable {
 408         private final DeviceSources deviceSources;
 409         private final NetconfSessionPreferences remoteSessionCapabilities;
 410         private final RemoteDeviceCommunicator<NetconfMessage> listener;
 411         private final NetconfDeviceCapabilities capabilities;
 412
 413         public SchemaSetup(final DeviceSources deviceSources, final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceCommunicator<NetconfMessage> listener) {
 414             this.deviceSources = deviceSources;
 415             this.remoteSessionCapabilities = remoteSessionCapabilities;
 416             this.listener = listener;
 417             this.capabilities = remoteSessionCapabilities.getNetconfDeviceCapabilities();
 418         }
 419
 420         @Override
 421         public void run() {
 422
 423             final Collection<SourceIdentifier> requiredSources = deviceSources.getRequiredSources();
 424             final Collection<SourceIdentifier> missingSources = filterMissingSources(requiredSources);
 425
 426             capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(missingSources),
 427                     UnavailableCapability.FailureReason.MissingSource);
 428
 429             requiredSources.removeAll(missingSources);
 430             setUpSchema(requiredSources);
 431         }
 432
 433         private Collection<SourceIdentifier> filterMissingSources(final Collection<SourceIdentifier> requiredSources) {
 434
 435             return requiredSources.parallelStream().filter(sourceIdentifier -> {
 436                     boolean remove = false;
 437                     try {
 438                         schemaRepository.getSchemaSource(sourceIdentifier, ASTSchemaSource.class).checkedGet();
 439                     } catch (SchemaSourceException e) {
 440                         remove = true;
 441                     }
 442                     return remove;
 443                 }).collect(Collectors.toList());
 444         }
 445
 446         /**
 447          * Build schema context, in case of success or final failure notify device
 448          */
 449         private void setUpSchema(Collection<SourceIdentifier> requiredSources) {
 450             while (!requiredSources.isEmpty()) {
 451                 LOG.trace("{}: Trying to build schema context from {}", id, requiredSources);
 452                 try {
 453                     final CheckedFuture<SchemaContext, SchemaResolutionException> schemaBuilderFuture = schemaContextFactory.createSchemaContext(requiredSources);
 454                     final SchemaContext result = schemaBuilderFuture.checkedGet();
 455                     LOG.debug("{}: Schema context built successfully from {}", id, requiredSources);
 456                     final Collection<QName> filteredQNames = Sets.difference(deviceSources.getRequiredSourcesQName(), capabilities.getUnresolvedCapabilites().keySet());
 457                     capabilities.addCapabilities(filteredQNames.stream().map(entry -> new AvailableCapabilityBuilder()
 458                             .setCapability(entry.toString()).setCapabilityOrigin(remoteSessionCapabilities.getModuleBasedCapsOrigin().get(entry)).build())
 459                             .collect(Collectors.toList()));
 460
 461                     capabilities.addNonModuleBasedCapabilities(remoteSessionCapabilities.getNonModuleCaps().stream().map(entry -> new AvailableCapabilityBuilder()
 462                             .setCapability(entry).setCapabilityOrigin(AvailableCapability.CapabilityOrigin.DeviceAdvertised).build())
 463                             .collect(Collectors.toList()));
 464
 465                     handleSalInitializationSuccess(result, remoteSessionCapabilities, getDeviceSpecificRpc(result));
 466                     return;
 467                 } catch (final Throwable t) {
 468                     if (t instanceof MissingSchemaSourceException){
 469                         requiredSources = handleMissingSchemaSourceException(requiredSources, (MissingSchemaSourceException) t);
 470                     } else if (t instanceof SchemaResolutionException) {
 471                         // schemaBuilderFuture.checkedGet() throws only SchemaResolutionException
 472                         // that might be wrapping a MissingSchemaSourceException so we need to look
 473                         // at the cause of the exception to make sure we don't misinterpret it.
 474                         if (t.getCause() instanceof MissingSchemaSourceException) {
 475                             requiredSources = handleMissingSchemaSourceException(requiredSources, (MissingSchemaSourceException) t.getCause());
 476                             continue;
 477                         }
 478                         requiredSources = handleSchemaResolutionException(requiredSources, (SchemaResolutionException) t);
 479                     } else {
 480                         // unknown error, fail
 481                         handleSalInitializationFailure(t, listener);
 482                         return;
 483                     }
 484                 }
 485             }
 486             // No more sources, fail
 487             final IllegalStateException cause = new IllegalStateException(id + ": No more sources for schema context");
 488             handleSalInitializationFailure(cause, listener);
 489             salFacade.onDeviceFailed(cause);
 490         }
 491
 492         private Collection<SourceIdentifier> handleMissingSchemaSourceException(final Collection<SourceIdentifier> requiredSources, final MissingSchemaSourceException t) {
 493             // In case source missing, try without it
 494             final SourceIdentifier missingSource = t.getSourceId();
 495             LOG.warn("{}: Unable to build schema context, missing source {}, will reattempt without it", id, missingSource);
 496             LOG.debug("{}: Unable to build schema context, missing source {}, will reattempt without it", t);
 497             final Collection<QName> qNameOfMissingSource = getQNameFromSourceIdentifiers(Sets.newHashSet(missingSource));
 498             if (!qNameOfMissingSource.isEmpty()) {
 499                 capabilities.addUnresolvedCapabilities(qNameOfMissingSource, UnavailableCapability.FailureReason.MissingSource);
 500             }
 501             return stripUnavailableSource(requiredSources, missingSource);
 502         }
 503
 504         private Collection<SourceIdentifier> handleSchemaResolutionException(final Collection<SourceIdentifier> requiredSources, final SchemaResolutionException resolutionException) {
 505             // In case resolution error, try only with resolved sources
 506             // There are two options why schema resolution exception occurred : unsatisfied imports or flawed model
 507             // FIXME Do we really have assurance that these two cases cannot happen at once?
 508             if (resolutionException.getFailedSource() != null) {
 509                 // flawed model - exclude it
 510                 final SourceIdentifier failedSourceId = resolutionException.getFailedSource();
 511                 LOG.warn("{}: Unable to build schema context, failed to resolve source {}, will reattempt without it", id, failedSourceId);
 512                 LOG.warn("{}: Unable to build schema context, failed to resolve source {}, will reattempt without it", id, resolutionException);
 513                 capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(Collections.singleton(failedSourceId)),
 514                         UnavailableCapability.FailureReason.UnableToResolve);
 515                 return stripUnavailableSource(requiredSources, resolutionException.getFailedSource());
 516             }
 517             // unsatisfied imports
 518             final Set<SourceIdentifier> unresolvedSources = resolutionException.getUnsatisfiedImports().keySet();
 519             capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(unresolvedSources), UnavailableCapability.FailureReason.UnableToResolve);
 520             LOG.warn("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only", id, resolutionException.getUnsatisfiedImports());
 521             LOG.debug("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only", resolutionException);
 522             return resolutionException.getResolvedSources();
 523         }
 524
 525         protected NetconfDeviceRpc getDeviceSpecificRpc(final SchemaContext result) {
 526             return new NetconfDeviceRpc(result, listener, new NetconfMessageTransformer(result, true));
 527         }
 528
 529         private Collection<SourceIdentifier> stripUnavailableSource(final Collection<SourceIdentifier> requiredSources, final SourceIdentifier sIdToRemove) {
 530             final LinkedList<SourceIdentifier> sourceIdentifiers = Lists.newLinkedList(requiredSources);
 531             final boolean removed = sourceIdentifiers.remove(sIdToRemove);
 532             Preconditions.checkState(removed, "{}: Trying to remove {} from {} failed", id, sIdToRemove, requiredSources);
 533             return sourceIdentifiers;
 534         }
 535
 536         private Collection<QName> getQNameFromSourceIdentifiers(final Collection<SourceIdentifier> identifiers) {
 537             final Collection<QName> qNames = Collections2.transform(identifiers, new Function<SourceIdentifier, QName>() {
 538                 @Override
 539                 public QName apply(final SourceIdentifier sourceIdentifier) {
 540                     return getQNameFromSourceIdentifier(sourceIdentifier);
 541                 }
 542             });
 543
 544             if (qNames.isEmpty()) {
 545                 LOG.debug("{}: Unable to map any source identifiers to a capability reported by device : {}", id, identifiers);
 546             }
 547             return Collections2.filter(qNames, Predicates.notNull());
 548         }
 549
 550         private QName getQNameFromSourceIdentifier(final SourceIdentifier identifier) {
 551             // Required sources are all required and provided merged in DeviceSourcesResolver
 552             for (final QName qname : deviceSources.getRequiredSourcesQName()) {
 553                 if(qname.getLocalName().equals(identifier.getName()) == false) {
 554                     continue;
 555                 }
 556
 557                 if(identifier.getRevision().equals(SourceIdentifier.NOT_PRESENT_FORMATTED_REVISION) &&
 558                         qname.getRevision() == null) {
 559                     return qname;
 560                 }
 561
 562                 if (qname.getFormattedRevision().equals(identifier.getRevision())) {
 563                     return qname;
 564                 }
 565             }
 566             LOG.warn("Unable to map identifier to a devices reported capability: {} Available: {}",identifier, deviceSources.getRequiredSourcesQName());
 567             // return null since we cannot find the QName, this capability will be removed from required sources and not reported as unresolved-capability
 568             return null;
 569         }
 570     }
 571 }