restconf/sal-rest-connector/src/main/java/org/opendaylight/netconf/sal/streams/listeners/ListenerAdapter.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.streams.listeners;
   9
  10 import com.google.common.base.Preconditions;
  11 import com.google.common.eventbus.AsyncEventBus;
  12 import com.google.common.eventbus.EventBus;
  13 import com.google.common.eventbus.Subscribe;
  14 import io.netty.channel.Channel;
  15 import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
  16 import io.netty.util.internal.ConcurrentSet;
  17 import java.io.ByteArrayOutputStream;
  18 import java.io.IOException;
  19 import java.io.OutputStreamWriter;
  20 import java.io.UnsupportedEncodingException;
  21 import java.nio.charset.StandardCharsets;
  22 import java.text.SimpleDateFormat;
  23 import java.util.Collection;
  24 import java.util.Date;
  25 import java.util.HashMap;
  26 import java.util.Map;
  27 import java.util.Map.Entry;
  28 import java.util.Random;
  29 import java.util.Set;
  30 import java.util.concurrent.Executors;
  31 import java.util.regex.Pattern;
  32 import javax.xml.parsers.DocumentBuilder;
  33 import javax.xml.parsers.DocumentBuilderFactory;
  34 import javax.xml.parsers.ParserConfigurationException;
  35 import javax.xml.stream.XMLOutputFactory;
  36 import javax.xml.stream.XMLStreamException;
  37 import javax.xml.stream.XMLStreamWriter;
  38 import javax.xml.transform.OutputKeys;
  39 import javax.xml.transform.Transformer;
  40 import javax.xml.transform.TransformerException;
  41 import javax.xml.transform.TransformerFactory;
  42 import javax.xml.transform.dom.DOMResult;
  43 import javax.xml.transform.dom.DOMSource;
  44 import javax.xml.transform.stream.StreamResult;
  45 import org.json.JSONObject;
  46 import org.json.XML;
  47 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeEvent;
  48 import org.opendaylight.controller.md.sal.dom.api.DOMDataChangeListener;
  49 import org.opendaylight.netconf.sal.restconf.impl.ControllerContext;
  50 import org.opendaylight.netconf.sal.restconf.impl.RestconfDocumentedException;
  51 import org.opendaylight.yang.gen.v1.urn.sal.restconf.event.subscription.rev140708.NotificationOutputTypeGrouping.NotificationOutputType;
  52 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  53 import org.opendaylight.yangtools.yang.common.QName;
  54 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  55 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifierWithPredicates;
  56 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeWithValue;
  57 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
  58 import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
  59 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  60 import org.opendaylight.yangtools.yang.data.api.schema.UnkeyedListEntryNode;
  61 import org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeStreamWriter;
  62 import org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter;
  63 import org.opendaylight.yangtools.yang.data.impl.codec.xml.XMLStreamNormalizedNodeStreamWriter;
  64 import org.opendaylight.yangtools.yang.data.impl.codec.xml.XmlDocumentUtils;
  65 import org.opendaylight.yangtools.yang.data.util.DataSchemaContextTree;
  66 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  67 import org.opendaylight.yangtools.yang.model.api.SchemaPath;
  68 import org.slf4j.Logger;
  69 import org.slf4j.LoggerFactory;
  70 import org.w3c.dom.Document;
  71 import org.w3c.dom.Element;
  72 import org.w3c.dom.Node;
  73
  74 /**
  75  * {@link ListenerAdapter} is responsible to track events, which occurred by changing data in data source.
  76  */
  77 public class ListenerAdapter implements DOMDataChangeListener {
  78
  79     private static final Logger LOG = LoggerFactory.getLogger(ListenerAdapter.class);
  80     private static final DocumentBuilderFactory DBF = DocumentBuilderFactory.newInstance();
  81     private static final TransformerFactory FACTORY = TransformerFactory.newInstance();
  82     private static final Pattern RFC3339_PATTERN = Pattern.compile("(\\d\\d)(\\d\\d)$");
  83
  84     private static final SimpleDateFormat RFC3339 = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ssZ");
  85
  86     private final YangInstanceIdentifier path;
  87     private ListenerRegistration<DOMDataChangeListener> registration;
  88     private final String streamName;
  89     private Set<Channel> subscribers = new ConcurrentSet<>();
  90     private final EventBus eventBus;
  91     private final EventBusChangeRecorder eventBusChangeRecorder;
  92     private final NotificationOutputType outputType;
  93     private Date start = null;
  94     private Date stop = null;
  95
  96     /**
  97      * Creates new {@link ListenerAdapter} listener specified by path and stream
  98      * name.
  99      *
 100      * @param path
 101      *            Path to data in data store.
 102      * @param streamName
 103      *            The name of the stream.
 104      * @param outputType
 105      *            - type of output on notification (JSON, XML)
 106      */
 107     ListenerAdapter(final YangInstanceIdentifier path, final String streamName,
 108             final NotificationOutputType outputType) {
 109         this.outputType = outputType;
 110         Preconditions.checkNotNull(path);
 111         Preconditions.checkArgument((streamName != null) && !streamName.isEmpty());
 112         this.path = path;
 113         this.streamName = streamName;
 114         this.eventBus = new AsyncEventBus(Executors.newSingleThreadExecutor());
 115         this.eventBusChangeRecorder = new EventBusChangeRecorder();
 116         this.eventBus.register(this.eventBusChangeRecorder);
 117     }
 118
 119     @Override
 120     public void onDataChanged(final AsyncDataChangeEvent<YangInstanceIdentifier, NormalizedNode<?, ?>> change) {
 121         final Date now = new Date();
 122         if (this.stop != null) {
 123             if ((this.start.compareTo(now) < 0) && (this.stop.compareTo(now) > 0)) {
 124                 prepareAndPostData(change);
 125             }
 126             if (this.stop.compareTo(now) < 0) {
 127                 try {
 128                     this.close();
 129                 } catch (final Exception e) {
 130                     throw new RestconfDocumentedException("Problem with unregister listener." + e);
 131                 }
 132             }
 133         } else if (this.start != null) {
 134             if (this.start.compareTo(now) < 0) {
 135                 this.start = null;
 136                 prepareAndPostData(change);
 137             }
 138         } else {
 139             prepareAndPostData(change);
 140         }
 141     }
 142
 143     private void prepareAndPostData(final AsyncDataChangeEvent<YangInstanceIdentifier, NormalizedNode<?, ?>> change) {
 144         if (!change.getCreatedData().isEmpty() || !change.getUpdatedData().isEmpty()
 145                 || !change.getRemovedPaths().isEmpty()) {
 146             final String xml = prepareXmlFrom(change);
 147             final Event event = new Event(EventType.NOTIFY);
 148             if (this.outputType.equals(NotificationOutputType.JSON)) {
 149                 final JSONObject jsonObject = XML.toJSONObject(xml);
 150                 event.setData(jsonObject.toString());
 151             } else {
 152                 event.setData(xml);
 153             }
 154             this.eventBus.post(event);
 155         }
 156     }
 157
 158     /**
 159      * Tracks events of data change by customer.
 160      */
 161     private final class EventBusChangeRecorder {
 162         @Subscribe
 163         public void recordCustomerChange(final Event event) {
 164             if (event.getType() == EventType.REGISTER) {
 165                 final Channel subscriber = event.getSubscriber();
 166                 if (!ListenerAdapter.this.subscribers.contains(subscriber)) {
 167                     ListenerAdapter.this.subscribers.add(subscriber);
 168                 }
 169             } else if (event.getType() == EventType.DEREGISTER) {
 170                 ListenerAdapter.this.subscribers.remove(event.getSubscriber());
 171                 Notificator.removeListenerIfNoSubscriberExists(ListenerAdapter.this);
 172             } else if (event.getType() == EventType.NOTIFY) {
 173                 for (final Channel subscriber : ListenerAdapter.this.subscribers) {
 174                     if (subscriber.isActive()) {
 175                         LOG.debug("Data are sent to subscriber {}:", subscriber.remoteAddress());
 176                         subscriber.writeAndFlush(new TextWebSocketFrame(event.getData()));
 177                     } else {
 178                         LOG.debug("Subscriber {} is removed - channel is not active yet.", subscriber.remoteAddress());
 179                         ListenerAdapter.this.subscribers.remove(subscriber);
 180                     }
 181                 }
 182             }
 183         }
 184     }
 185
 186     /**
 187      * Represents event of specific {@link EventType} type, holds data and {@link Channel} subscriber.
 188      */
 189     private final class Event {
 190         private final EventType type;
 191         private Channel subscriber;
 192         private String data;
 193
 194         /**
 195          * Creates new event specified by {@link EventType} type.
 196          *
 197          * @param type
 198          *            EventType
 199          */
 200         public Event(final EventType type) {
 201             this.type = type;
 202         }
 203
 204         /**
 205          * Gets the {@link Channel} subscriber.
 206          *
 207          * @return Channel
 208          */
 209         public Channel getSubscriber() {
 210             return this.subscriber;
 211         }
 212
 213         /**
 214          * Sets subscriber for event.
 215          *
 216          * @param subscriber
 217          *            Channel
 218          */
 219         public void setSubscriber(final Channel subscriber) {
 220             this.subscriber = subscriber;
 221         }
 222
 223         /**
 224          * Gets event String.
 225          *
 226          * @return String representation of event data.
 227          */
 228         public String getData() {
 229             return this.data;
 230         }
 231
 232         /**
 233          * Sets event data.
 234          *
 235          * @param data String.
 236          */
 237         public void setData(final String data) {
 238             this.data = data;
 239         }
 240
 241         /**
 242          * Gets event type.
 243          *
 244          * @return The type of the event.
 245          */
 246         public EventType getType() {
 247             return this.type;
 248         }
 249     }
 250
 251     /**
 252      * Type of the event.
 253      */
 254     private enum EventType {
 255         REGISTER,
 256         DEREGISTER,
 257         NOTIFY;
 258     }
 259
 260     /**
 261      * Prepare data in printable form and transform it to String.
 262      *
 263      * @param change
 264      *            DataChangeEvent
 265      * @return Data in printable form.
 266      */
 267     private String prepareXmlFrom(final AsyncDataChangeEvent<YangInstanceIdentifier, NormalizedNode<?, ?>> change) {
 268         final SchemaContext schemaContext = ControllerContext.getInstance().getGlobalSchema();
 269         final DataSchemaContextTree dataContextTree =  DataSchemaContextTree.from(schemaContext);
 270         final Document doc = createDocument();
 271         final Element notificationElement = doc.createElementNS("urn:ietf:params:xml:ns:netconf:notification:1.0",
 272                 "notification");
 273
 274         doc.appendChild(notificationElement);
 275
 276         final Element eventTimeElement = doc.createElement("eventTime");
 277         eventTimeElement.setTextContent(toRFC3339(new Date()));
 278         notificationElement.appendChild(eventTimeElement);
 279
 280         final Element dataChangedNotificationEventElement = doc.createElementNS(
 281                 "urn:opendaylight:params:xml:ns:yang:controller:md:sal:remote", "data-changed-notification");
 282
 283         addValuesToDataChangedNotificationEventElement(doc, dataChangedNotificationEventElement, change,
 284                 schemaContext, dataContextTree);
 285         notificationElement.appendChild(dataChangedNotificationEventElement);
 286
 287         try {
 288             final ByteArrayOutputStream out = new ByteArrayOutputStream();
 289             final Transformer transformer = FACTORY.newTransformer();
 290             transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
 291             transformer.setOutputProperty(OutputKeys.METHOD, "xml");
 292             transformer.setOutputProperty(OutputKeys.INDENT, "yes");
 293             transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
 294             transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
 295             transformer.transform(new DOMSource(doc),
 296                     new StreamResult(new OutputStreamWriter(out, StandardCharsets.UTF_8)));
 297             final byte[] charData = out.toByteArray();
 298             return new String(charData, "UTF-8");
 299         } catch (TransformerException | UnsupportedEncodingException e) {
 300             final String msg = "Error during transformation of Document into String";
 301             LOG.error(msg, e);
 302             return msg;
 303         }
 304     }
 305
 306     /**
 307      * Formats data specified by RFC3339.
 308      *
 309      * @param d
 310      *            Date
 311      * @return Data specified by RFC3339.
 312      */
 313     public static String toRFC3339(final Date d) {
 314         return RFC3339_PATTERN.matcher(RFC3339.format(d)).replaceAll("$1:$2");
 315     }
 316
 317     /**
 318      * Creates {@link Document} document.
 319      * @return {@link Document} document.
 320      */
 321     public static Document createDocument() {
 322         final DocumentBuilder bob;
 323         try {
 324             bob = DBF.newDocumentBuilder();
 325         } catch (final ParserConfigurationException e) {
 326             return null;
 327         }
 328         return bob.newDocument();
 329     }
 330
 331     /**
 332      * Adds values to data changed notification event element.
 333      *
 334      * @param doc
 335      *            {@link Document}
 336      * @param dataChangedNotificationEventElement
 337      *            {@link Element}
 338      * @param change
 339      *            {@link AsyncDataChangeEvent}
 340      */
 341     private void addValuesToDataChangedNotificationEventElement(final Document doc,
 342             final Element dataChangedNotificationEventElement,
 343             final AsyncDataChangeEvent<YangInstanceIdentifier, NormalizedNode<?, ?>> change,
 344             final SchemaContext  schemaContext, final DataSchemaContextTree dataSchemaContextTree) {
 345
 346         addCreatedChangedValuesFromDataToElement(doc, change.getCreatedData().entrySet(),
 347                 dataChangedNotificationEventElement,
 348                 Operation.CREATED, schemaContext, dataSchemaContextTree);
 349
 350         addCreatedChangedValuesFromDataToElement(doc, change.getUpdatedData().entrySet(),
 351                     dataChangedNotificationEventElement,
 352                     Operation.UPDATED, schemaContext, dataSchemaContextTree);
 353
 354         addValuesFromDataToElement(doc, change.getRemovedPaths(), dataChangedNotificationEventElement,
 355                 Operation.DELETED);
 356     }
 357
 358     /**
 359      * Adds values from data to element.
 360      *
 361      * @param doc
 362      *            {@link Document}
 363      * @param data
 364      *            Set of {@link YangInstanceIdentifier}.
 365      * @param element
 366      *            {@link Element}
 367      * @param operation
 368      *            {@link Operation}
 369      */
 370     private void addValuesFromDataToElement(final Document doc, final Set<YangInstanceIdentifier> data,
 371             final Element element, final Operation operation) {
 372         if ((data == null) || data.isEmpty()) {
 373             return;
 374         }
 375         for (final YangInstanceIdentifier path : data) {
 376             if (!ControllerContext.getInstance().isNodeMixin(path)) {
 377                 final Node node = createDataChangeEventElement(doc, path, operation);
 378                 element.appendChild(node);
 379             }
 380         }
 381     }
 382
 383     private void addCreatedChangedValuesFromDataToElement(final Document doc, final Set<Entry<YangInstanceIdentifier,
 384                 NormalizedNode<?,?>>> data, final Element element, final Operation operation, final SchemaContext
 385             schemaContext, final DataSchemaContextTree dataSchemaContextTree) {
 386         if ((data == null) || data.isEmpty()) {
 387             return;
 388         }
 389         for (final Entry<YangInstanceIdentifier, NormalizedNode<?, ?>> entry : data) {
 390             if (!ControllerContext.getInstance().isNodeMixin(entry.getKey())) {
 391                 final Node node = createCreatedChangedDataChangeEventElement(doc, entry, operation, schemaContext,
 392                         dataSchemaContextTree);
 393                 element.appendChild(node);
 394             }
 395         }
 396     }
 397
 398     /**
 399      * Creates changed event element from data.
 400      *
 401      * @param doc
 402      *            {@link Document}
 403      * @param path
 404      *            Path to data in data store.
 405      * @param operation
 406      *            {@link Operation}
 407      * @return {@link Node} node represented by changed event element.
 408      */
 409     private Node createDataChangeEventElement(final Document doc, final YangInstanceIdentifier path,
 410             final Operation operation) {
 411         final Element dataChangeEventElement = doc.createElement("data-change-event");
 412         final Element pathElement = doc.createElement("path");
 413         addPathAsValueToElement(path, pathElement);
 414         dataChangeEventElement.appendChild(pathElement);
 415
 416         final Element operationElement = doc.createElement("operation");
 417         operationElement.setTextContent(operation.value);
 418         dataChangeEventElement.appendChild(operationElement);
 419
 420         return dataChangeEventElement;
 421     }
 422
 423     private Node createCreatedChangedDataChangeEventElement(final Document doc, final Entry<YangInstanceIdentifier,
 424             NormalizedNode<?, ?>> entry, final Operation operation, final SchemaContext
 425             schemaContext, final DataSchemaContextTree dataSchemaContextTree) {
 426         final Element dataChangeEventElement = doc.createElement("data-change-event");
 427         final Element pathElement = doc.createElement("path");
 428         final YangInstanceIdentifier path = entry.getKey();
 429         addPathAsValueToElement(path, pathElement);
 430         dataChangeEventElement.appendChild(pathElement);
 431
 432         final Element operationElement = doc.createElement("operation");
 433         operationElement.setTextContent(operation.value);
 434         dataChangeEventElement.appendChild(operationElement);
 435
 436         try {
 437             final DOMResult domResult = writeNormalizedNode(entry.getValue(), path,
 438                     schemaContext, dataSchemaContextTree);
 439             final Node result = doc.importNode(domResult.getNode().getFirstChild(), true);
 440             final Element dataElement = doc.createElement("data");
 441             dataElement.appendChild(result);
 442             dataChangeEventElement.appendChild(dataElement);
 443         } catch (final IOException e) {
 444             LOG.error("Error in writer ", e);
 445         } catch (final XMLStreamException e) {
 446             LOG.error("Error processing stream", e);
 447         }
 448
 449         return dataChangeEventElement;
 450     }
 451
 452     private static DOMResult writeNormalizedNode(final NormalizedNode<?, ?> normalized,
 453                                                  final YangInstanceIdentifier path, final SchemaContext context,
 454                                                  final DataSchemaContextTree dataSchemaContextTree)
 455             throws IOException, XMLStreamException {
 456         final XMLOutputFactory XML_FACTORY = XMLOutputFactory.newFactory();
 457         final Document doc = XmlDocumentUtils.getDocument();
 458         final DOMResult result = new DOMResult(doc);
 459         NormalizedNodeWriter normalizedNodeWriter = null;
 460         NormalizedNodeStreamWriter normalizedNodeStreamWriter = null;
 461         XMLStreamWriter writer = null;
 462         final SchemaPath nodePath;
 463
 464         if ((normalized instanceof MapEntryNode) || (normalized instanceof UnkeyedListEntryNode)) {
 465             nodePath = dataSchemaContextTree.getChild(path).getDataSchemaNode().getPath();
 466         } else {
 467             nodePath = dataSchemaContextTree.getChild(path).getDataSchemaNode().getPath().getParent();
 468         }
 469
 470         try {
 471             writer = XML_FACTORY.createXMLStreamWriter(result);
 472             normalizedNodeStreamWriter = XMLStreamNormalizedNodeStreamWriter.create(writer, context, nodePath);
 473             normalizedNodeWriter = NormalizedNodeWriter.forStreamWriter(normalizedNodeStreamWriter);
 474
 475             normalizedNodeWriter.write(normalized);
 476
 477             normalizedNodeWriter.flush();
 478         } finally {
 479             if (normalizedNodeWriter != null) {
 480                 normalizedNodeWriter.close();
 481             }
 482             if (normalizedNodeStreamWriter != null) {
 483                 normalizedNodeStreamWriter.close();
 484             }
 485             if (writer != null) {
 486                 writer.close();
 487             }
 488         }
 489
 490         return result;
 491     }
 492
 493     /**
 494      * Adds path as value to element.
 495      *
 496      * @param path
 497      *            Path to data in data store.
 498      * @param element
 499      *            {@link Element}
 500      */
 501     private void addPathAsValueToElement(final YangInstanceIdentifier path, final Element element) {
 502         // Map< key = namespace, value = prefix>
 503         final Map<String, String> prefixes = new HashMap<>();
 504         final YangInstanceIdentifier normalizedPath = ControllerContext.getInstance().toXpathRepresentation(path);
 505         final StringBuilder textContent = new StringBuilder();
 506
 507         // FIXME: BUG-1281: this is duplicated code from yangtools (BUG-1275)
 508         for (final PathArgument pathArgument : normalizedPath.getPathArguments()) {
 509             if (pathArgument instanceof YangInstanceIdentifier.AugmentationIdentifier) {
 510                 continue;
 511             }
 512             textContent.append("/");
 513             writeIdentifierWithNamespacePrefix(element, textContent, pathArgument.getNodeType(), prefixes);
 514             if (pathArgument instanceof NodeIdentifierWithPredicates) {
 515                 final Map<QName, Object> predicates = ((NodeIdentifierWithPredicates) pathArgument).getKeyValues();
 516                 for (final QName keyValue : predicates.keySet()) {
 517                     final String predicateValue = String.valueOf(predicates.get(keyValue));
 518                     textContent.append("[");
 519                     writeIdentifierWithNamespacePrefix(element, textContent, keyValue, prefixes);
 520                     textContent.append("='");
 521                     textContent.append(predicateValue);
 522                     textContent.append("'");
 523                     textContent.append("]");
 524                 }
 525             } else if (pathArgument instanceof NodeWithValue) {
 526                 textContent.append("[.='");
 527                 textContent.append(((NodeWithValue) pathArgument).getValue());
 528                 textContent.append("'");
 529                 textContent.append("]");
 530             }
 531         }
 532         element.setTextContent(textContent.toString());
 533     }
 534
 535     /**
 536      * Writes identifier that consists of prefix and QName.
 537      *
 538      * @param element
 539      *            {@link Element}
 540      * @param textContent
 541      *            StringBuilder
 542      * @param qName
 543      *            QName
 544      * @param prefixes
 545      *            Map of namespaces and prefixes.
 546      */
 547     private static void writeIdentifierWithNamespacePrefix(final Element element, final StringBuilder textContent,
 548             final QName qName, final Map<String, String> prefixes) {
 549         final String namespace = qName.getNamespace().toString();
 550         String prefix = prefixes.get(namespace);
 551         if (prefix == null) {
 552             prefix = generateNewPrefix(prefixes.values());
 553         }
 554
 555         element.setAttribute("xmlns:" + prefix, namespace);
 556         textContent.append(prefix);
 557         prefixes.put(namespace, prefix);
 558
 559         textContent.append(":");
 560         textContent.append(qName.getLocalName());
 561     }
 562
 563     /**
 564      * Generates new prefix which consists of four random characters <a-z>.
 565      *
 566      * @param prefixes
 567      *            Collection of prefixes.
 568      * @return New prefix which consists of four random characters <a-z>.
 569      */
 570     private static String generateNewPrefix(final Collection<String> prefixes) {
 571         StringBuilder result = null;
 572         final Random random = new Random();
 573         do {
 574             result = new StringBuilder();
 575             for (int i = 0; i < 4; i++) {
 576                 final int randomNumber = 0x61 + (Math.abs(random.nextInt()) % 26);
 577                 result.append(Character.toChars(randomNumber));
 578             }
 579         } while (prefixes.contains(result.toString()));
 580
 581         return result.toString();
 582     }
 583
 584     /**
 585      * Gets path pointed to data in data store.
 586      *
 587      * @return Path pointed to data in data store.
 588      */
 589     public YangInstanceIdentifier getPath() {
 590         return this.path;
 591     }
 592
 593     /**
 594      * Sets {@link ListenerRegistration} registration.
 595      *
 596      * @param registration DOMDataChangeListener registration
 597      */
 598     public void setRegistration(final ListenerRegistration<DOMDataChangeListener> registration) {
 599         this.registration = registration;
 600     }
 601
 602     /**
 603      * Gets the name of the stream.
 604      *
 605      * @return The name of the stream.
 606      */
 607     public String getStreamName() {
 608         return this.streamName;
 609     }
 610
 611     /**
 612      * Removes all subscribers and unregisters event bus change recorder form event bus.
 613      */
 614     public void close() throws Exception {
 615         this.subscribers = new ConcurrentSet<>();
 616         this.registration.close();
 617         this.registration = null;
 618         this.eventBus.unregister(this.eventBusChangeRecorder);
 619     }
 620
 621     /**
 622      * Checks if {@link ListenerRegistration} registration exist.
 623      *
 624      * @return True if exist, false otherwise.
 625      */
 626     public boolean isListening() {
 627         return this.registration == null ? false : true;
 628     }
 629
 630     /**
 631      * Creates event of type {@link EventType#REGISTER}, set {@link Channel} subscriber to the event and post event into
 632      * event bus.
 633      *
 634      * @param subscriber
 635      *            Channel
 636      */
 637     public void addSubscriber(final Channel subscriber) {
 638         if (!subscriber.isActive()) {
 639             LOG.debug("Channel is not active between websocket server and subscriber {}" + subscriber.remoteAddress());
 640         }
 641         final Event event = new Event(EventType.REGISTER);
 642         event.setSubscriber(subscriber);
 643         this.eventBus.post(event);
 644     }
 645
 646     /**
 647      * Creates event of type {@link EventType#DEREGISTER}, sets {@link Channel} subscriber to the event and posts event
 648      * into event bus.
 649      *
 650      * @param subscriber
 651      */
 652     public void removeSubscriber(final Channel subscriber) {
 653         LOG.debug("Subscriber {} is removed.", subscriber.remoteAddress());
 654         final Event event = new Event(EventType.DEREGISTER);
 655         event.setSubscriber(subscriber);
 656         this.eventBus.post(event);
 657     }
 658
 659     /**
 660      * Checks if exists at least one {@link Channel} subscriber.
 661      *
 662      * @return True if exist at least one {@link Channel} subscriber, false otherwise.
 663      */
 664     public boolean hasSubscribers() {
 665         return !this.subscribers.isEmpty();
 666     }
 667
 668     /**
 669      * Consists of two types {@link Store#CONFIG} and {@link Store#OPERATION}.
 670      */
 671     private static enum Store {
 672         CONFIG("config"),
 673         OPERATION("operation");
 674
 675         private final String value;
 676
 677         private Store(final String value) {
 678             this.value = value;
 679         }
 680     }
 681
 682     /**
 683      * Consists of three types {@link Operation#CREATED}, {@link Operation#UPDATED} and {@link Operation#DELETED}.
 684      */
 685     private static enum Operation {
 686         CREATED("created"),
 687         UPDATED("updated"),
 688         DELETED("deleted");
 689
 690         private final String value;
 691
 692         private Operation(final String value) {
 693             this.value = value;
 694         }
 695     }
 696
 697     /**
 698      * Set query parameters for listener
 699      *
 700      * @param start
 701      *            - start-time of getting notification
 702      * @param stop
 703      *            - stop-time of getting notification
 704      */
 705     public void setTimer(final Date start, final Date stop) {
 706         this.start = start;
 707         this.stop = stop;
 708     }
 709
 710 }