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