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   1 /**
   2  * Copyright (c) 2010-2020 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13
  14 package org.openhab.binding.ipcamera.internal;
  15
  16 import static org.openhab.binding.ipcamera.internal.IpCameraBindingConstants.*;
  17
  18 import java.nio.charset.StandardCharsets;
  19 import java.util.ArrayList;
  20
  21 import org.eclipse.jdt.annotation.NonNullByDefault;
  22 import org.eclipse.jdt.annotation.Nullable;
  23 import org.openhab.binding.ipcamera.internal.handler.IpCameraHandler;
  24 import org.openhab.core.library.types.OnOffType;
  25 import org.openhab.core.library.types.StringType;
  26 import org.openhab.core.thing.ChannelUID;
  27 import org.openhab.core.thing.binding.ThingHandler;
  28 import org.openhab.core.types.Command;
  29 import org.openhab.core.types.RefreshType;
  30 import org.slf4j.Logger;
  31 import org.slf4j.LoggerFactory;
  32
  33 import io.netty.buffer.ByteBuf;
  34 import io.netty.buffer.Unpooled;
  35 import io.netty.channel.ChannelDuplexHandler;
  36 import io.netty.channel.ChannelHandlerContext;
  37 import io.netty.handler.codec.http.DefaultFullHttpRequest;
  38 import io.netty.handler.codec.http.FullHttpRequest;
  39 import io.netty.handler.codec.http.HttpHeaderNames;
  40 import io.netty.handler.codec.http.HttpHeaderValues;
  41 import io.netty.handler.codec.http.HttpMethod;
  42 import io.netty.handler.codec.http.HttpVersion;
  43 import io.netty.util.ReferenceCountUtil;
  44
  45 /**
  46  * The {@link HikvisionHandler} is responsible for handling commands, which are
  47  * sent to one of the channels.
  48  *
  49  * @author Matthew Skinner - Initial contribution
  50  */
  51
  52 @NonNullByDefault
  53 public class HikvisionHandler extends ChannelDuplexHandler {
  54     private final Logger logger = LoggerFactory.getLogger(getClass());
  55     private IpCameraHandler ipCameraHandler;
  56     private int nvrChannel;
  57     private int lineCount, vmdCount, leftCount, takenCount, faceCount, pirCount, fieldCount;
  58
  59     public HikvisionHandler(ThingHandler handler, int nvrChannel) {
  60         ipCameraHandler = (IpCameraHandler) handler;
  61         this.nvrChannel = nvrChannel;
  62     }
  63
  64     // This handles the incoming http replies back from the camera.
  65     @Override
  66     public void channelRead(@Nullable ChannelHandlerContext ctx, @Nullable Object msg) throws Exception {
  67         if (msg == null || ctx == null) {
  68             return;
  69         }
  70         try {
  71             int debounce = 3;
  72             String content = msg.toString();
  73             logger.trace("HTTP Result back from camera is \t:{}:", content);
  74             if (content.contains("--boundary")) {// Alarm checking goes in here//
  75                 if (content.contains("<EventNotificationAlert version=\"")) {
  76                     if (content.contains("hannelID>" + nvrChannel + "</")) {// some camera use c or <dynChannelID>
  77                         if (content.contains("<eventType>linedetection</eventType>")) {
  78                             ipCameraHandler.motionDetected(CHANNEL_LINE_CROSSING_ALARM);
  79                             lineCount = debounce;
  80                         }
  81                         if (content.contains("<eventType>fielddetection</eventType>")) {
  82                             ipCameraHandler.motionDetected(CHANNEL_FIELD_DETECTION_ALARM);
  83                             fieldCount = debounce;
  84                         }
  85                         if (content.contains("<eventType>VMD</eventType>")) {
  86                             ipCameraHandler.motionDetected(CHANNEL_MOTION_ALARM);
  87                             vmdCount = debounce;
  88                         }
  89                         if (content.contains("<eventType>facedetection</eventType>")) {
  90                             ipCameraHandler.setChannelState(CHANNEL_FACE_DETECTED, OnOffType.ON);
  91                             faceCount = debounce;
  92                         }
  93                         if (content.contains("<eventType>unattendedBaggage</eventType>")) {
  94                             ipCameraHandler.setChannelState(CHANNEL_ITEM_LEFT, OnOffType.ON);
  95                             leftCount = debounce;
  96                         }
  97                         if (content.contains("<eventType>attendedBaggage</eventType>")) {
  98                             ipCameraHandler.setChannelState(CHANNEL_ITEM_TAKEN, OnOffType.ON);
  99                             takenCount = debounce;
 100                         }
 101                         if (content.contains("<eventType>PIR</eventType>")) {
 102                             ipCameraHandler.motionDetected(CHANNEL_PIR_ALARM);
 103                             pirCount = debounce;
 104                         }
 105                         if (content.contains("<eventType>videoloss</eventType>\r\n<eventState>inactive</eventState>")) {
 106                             if (vmdCount > 1) {
 107                                 vmdCount = 1;
 108                             }
 109                             countDown();
 110                             countDown();
 111                         }
 112                     } else if (content.contains("<channelID>0</channelID>")) {// NVR uses channel 0 to say all
 113                                                                               // channels
 114                         if (content.contains("<eventType>videoloss</eventType>\r\n<eventState>inactive</eventState>")) {
 115                             if (vmdCount > 1) {
 116                                 vmdCount = 1;
 117                             }
 118                             countDown();
 119                             countDown();
 120                         }
 121                     }
 122                     countDown();
 123                 }
 124             } else {
 125                 String replyElement = Helper.fetchXML(content, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>", "<");
 126                 switch (replyElement) {
 127                     case "MotionDetection version=":
 128                         ipCameraHandler.storeHttpReply(
 129                                 "/ISAPI/System/Video/inputs/channels/" + nvrChannel + "01/motionDetection", content);
 130                         if (content.contains("<enabled>true</enabled>")) {
 131                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_MOTION_ALARM, OnOffType.ON);
 132                         } else if (content.contains("<enabled>false</enabled>")) {
 133                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_MOTION_ALARM, OnOffType.OFF);
 134                         }
 135                         break;
 136                     case "IOInputPort version=":
 137                         ipCameraHandler.storeHttpReply("/ISAPI/System/IO/inputs/" + nvrChannel, content);
 138                         if (content.contains("<enabled>true</enabled>")) {
 139                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_EXTERNAL_ALARM_INPUT, OnOffType.ON);
 140                         } else if (content.contains("<enabled>false</enabled>")) {
 141                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_EXTERNAL_ALARM_INPUT, OnOffType.OFF);
 142                         }
 143                         if (content.contains("<triggering>low</triggering>")) {
 144                             ipCameraHandler.setChannelState(CHANNEL_TRIGGER_EXTERNAL_ALARM_INPUT, OnOffType.OFF);
 145                         } else if (content.contains("<triggering>high</triggering>")) {
 146                             ipCameraHandler.setChannelState(CHANNEL_TRIGGER_EXTERNAL_ALARM_INPUT, OnOffType.ON);
 147                         }
 148                         break;
 149                     case "LineDetection":
 150                         ipCameraHandler.storeHttpReply("/ISAPI/Smart/LineDetection/" + nvrChannel + "01", content);
 151                         if (content.contains("<enabled>true</enabled>")) {
 152                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_LINE_CROSSING_ALARM, OnOffType.ON);
 153                         } else if (content.contains("<enabled>false</enabled>")) {
 154                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_LINE_CROSSING_ALARM, OnOffType.OFF);
 155                         }
 156                         break;
 157                     case "TextOverlay version=":
 158                         ipCameraHandler.storeHttpReply(
 159                                 "/ISAPI/System/Video/inputs/channels/" + nvrChannel + "/overlays/text/1", content);
 160                         String text = Helper.fetchXML(content, "<enabled>true</enabled>", "<displayText>");
 161                         ipCameraHandler.setChannelState(CHANNEL_TEXT_OVERLAY, StringType.valueOf(text));
 162                         break;
 163                     case "AudioDetection version=":
 164                         ipCameraHandler.storeHttpReply("/ISAPI/Smart/AudioDetection/channels/" + nvrChannel + "01",
 165                                 content);
 166                         if (content.contains("<enabled>true</enabled>")) {
 167                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_AUDIO_ALARM, OnOffType.ON);
 168                         } else if (content.contains("<enabled>false</enabled>")) {
 169                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_AUDIO_ALARM, OnOffType.OFF);
 170                         }
 171                         break;
 172                     case "IOPortStatus version=":
 173                         if (content.contains("<ioState>active</ioState>")) {
 174                             ipCameraHandler.setChannelState(CHANNEL_EXTERNAL_ALARM_INPUT, OnOffType.ON);
 175                         } else if (content.contains("<ioState>inactive</ioState>")) {
 176                             ipCameraHandler.setChannelState(CHANNEL_EXTERNAL_ALARM_INPUT, OnOffType.OFF);
 177                         }
 178                         break;
 179                     case "FieldDetection version=":
 180                         ipCameraHandler.storeHttpReply("/ISAPI/Smart/FieldDetection/" + nvrChannel + "01", content);
 181                         if (content.contains("<enabled>true</enabled>")) {
 182                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_FIELD_DETECTION_ALARM, OnOffType.ON);
 183                         } else if (content.contains("<enabled>false</enabled>")) {
 184                             ipCameraHandler.setChannelState(CHANNEL_ENABLE_FIELD_DETECTION_ALARM, OnOffType.OFF);
 185                         }
 186                         break;
 187                     case "ResponseStatus version=":
 188                         ////////////////// External Alarm Input ///////////////
 189                         if (content.contains(
 190                                 "<requestURL>/ISAPI/System/IO/inputs/" + nvrChannel + "/status</requestURL>")) {
 191                             // Stops checking the external alarm if camera does not have feature.
 192                             if (content.contains("<statusString>Invalid Operation</statusString>")) {
 193                                 ipCameraHandler.lowPriorityRequests.remove(0);
 194                                 ipCameraHandler.logger.debug(
 195                                         "Stopping checks for alarm inputs as camera appears to be missing this feature.");
 196                             }
 197                         }
 198                         break;
 199                     default:
 200                         if (content.contains("<EventNotificationAlert")) {
 201                             if (content.contains("hannelID>" + nvrChannel + "</")
 202                                     || content.contains("<channelID>0</channelID>")) {// some camera use c or
 203                                                                                       // <dynChannelID>
 204                                 if (content.contains(
 205                                         "<eventType>videoloss</eventType>\r\n<eventState>inactive</eventState>")) {
 206                                     if (vmdCount > 1) {
 207                                         vmdCount = 1;
 208                                     }
 209                                     countDown();
 210                                     countDown();
 211                                 }
 212                                 countDown();
 213                             }
 214                         } else {
 215                             logger.debug("Unhandled reply-{}.", content);
 216                         }
 217                         break;
 218                 }
 219             }
 220         } finally {
 221             ReferenceCountUtil.release(msg);
 222         }
 223     }
 224
 225     // This does debouncing of the alarms
 226     void countDown() {
 227         if (lineCount > 1) {
 228             lineCount--;
 229         } else if (lineCount == 1) {
 230             ipCameraHandler.setChannelState(CHANNEL_LINE_CROSSING_ALARM, OnOffType.OFF);
 231             lineCount--;
 232         }
 233         if (vmdCount > 1) {
 234             vmdCount--;
 235         } else if (vmdCount == 1) {
 236             ipCameraHandler.setChannelState(CHANNEL_MOTION_ALARM, OnOffType.OFF);
 237             vmdCount--;
 238         }
 239         if (leftCount > 1) {
 240             leftCount--;
 241         } else if (leftCount == 1) {
 242             ipCameraHandler.setChannelState(CHANNEL_ITEM_LEFT, OnOffType.OFF);
 243             leftCount--;
 244         }
 245         if (takenCount > 1) {
 246             takenCount--;
 247         } else if (takenCount == 1) {
 248             ipCameraHandler.setChannelState(CHANNEL_ITEM_TAKEN, OnOffType.OFF);
 249             takenCount--;
 250         }
 251         if (faceCount > 1) {
 252             faceCount--;
 253         } else if (faceCount == 1) {
 254             ipCameraHandler.setChannelState(CHANNEL_FACE_DETECTED, OnOffType.OFF);
 255             faceCount--;
 256         }
 257         if (pirCount > 1) {
 258             pirCount--;
 259         } else if (pirCount == 1) {
 260             ipCameraHandler.setChannelState(CHANNEL_PIR_ALARM, OnOffType.OFF);
 261             pirCount--;
 262         }
 263         if (fieldCount > 1) {
 264             fieldCount--;
 265         } else if (fieldCount == 1) {
 266             ipCameraHandler.setChannelState(CHANNEL_FIELD_DETECTION_ALARM, OnOffType.OFF);
 267             fieldCount--;
 268         }
 269         if (fieldCount == 0 && pirCount == 0 && faceCount == 0 && takenCount == 0 && leftCount == 0 && vmdCount == 0
 270                 && lineCount == 0) {
 271             ipCameraHandler.noMotionDetected(CHANNEL_MOTION_ALARM);
 272         }
 273     }
 274
 275     public void hikSendXml(String httpPutURL, String xml) {
 276         logger.trace("Body for PUT:{} is going to be:{}", httpPutURL, xml);
 277         FullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, new HttpMethod("PUT"), httpPutURL);
 278         request.headers().set(HttpHeaderNames.HOST, ipCameraHandler.cameraConfig.getIp());
 279         request.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.CLOSE);
 280         request.headers().add(HttpHeaderNames.CONTENT_TYPE, "application/xml; charset=\"UTF-8\"");
 281         ByteBuf bbuf = Unpooled.copiedBuffer(xml, StandardCharsets.UTF_8);
 282         request.headers().set(HttpHeaderNames.CONTENT_LENGTH, bbuf.readableBytes());
 283         request.content().clear().writeBytes(bbuf);
 284         ipCameraHandler.sendHttpPUT(httpPutURL, request);
 285     }
 286
 287     public void hikChangeSetting(String httpGetPutURL, String removeElement, String replaceRemovedElementWith) {
 288         ChannelTracking localTracker = ipCameraHandler.channelTrackingMap.get(httpGetPutURL);
 289         if (localTracker == null) {
 290             ipCameraHandler.sendHttpGET(httpGetPutURL);
 291             logger.debug(
 292                     "Did not have a reply stored before hikChangeSetting was run, try again shortly as a reply has just been requested.");
 293             return;
 294         }
 295         String body = localTracker.getReply();
 296         if (body.isEmpty()) {
 297             logger.debug(
 298                     "Did not have a reply stored before hikChangeSetting was run, try again shortly as a reply has just been requested.");
 299             ipCameraHandler.sendHttpGET(httpGetPutURL);
 300         } else {
 301             logger.trace("An OLD reply from the camera was:{}", body);
 302             if (body.contains("<?xml version=\"1.0\" encoding=\"UTF-8\"?>")) {
 303                 body = body.substring("<?xml version=\"1.0\" encoding=\"UTF-8\"?>".length());
 304             }
 305             int elementIndexStart = body.indexOf("<" + removeElement + ">");
 306             int elementIndexEnd = body.indexOf("</" + removeElement + ">");
 307             body = body.substring(0, elementIndexStart) + replaceRemovedElementWith
 308                     + body.substring(elementIndexEnd + removeElement.length() + 3, body.length());
 309             logger.trace("Body for this PUT is going to be:{}", body);
 310             localTracker.setReply(body);
 311             FullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, new HttpMethod("PUT"),
 312                     httpGetPutURL);
 313             request.headers().set(HttpHeaderNames.HOST, ipCameraHandler.cameraConfig.getIp());
 314             request.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.CLOSE);
 315             request.headers().add(HttpHeaderNames.CONTENT_TYPE, "application/xml; charset=\"UTF-8\"");
 316             ByteBuf bbuf = Unpooled.copiedBuffer(body, StandardCharsets.UTF_8);
 317             request.headers().set(HttpHeaderNames.CONTENT_LENGTH, bbuf.readableBytes());
 318             request.content().clear().writeBytes(bbuf);
 319             ipCameraHandler.sendHttpPUT(httpGetPutURL, request);
 320         }
 321     }
 322
 323     // This handles the commands that come from the Openhab event bus.
 324     public void handleCommand(ChannelUID channelUID, Command command) {
 325         if (command instanceof RefreshType) {
 326             switch (channelUID.getId()) {
 327                 case CHANNEL_ENABLE_AUDIO_ALARM:
 328                     ipCameraHandler.sendHttpGET("/ISAPI/Smart/AudioDetection/channels/" + nvrChannel + "01");
 329                     return;
 330                 case CHANNEL_ENABLE_LINE_CROSSING_ALARM:
 331                     ipCameraHandler.sendHttpGET("/ISAPI/Smart/LineDetection/" + nvrChannel + "01");
 332                     return;
 333                 case CHANNEL_ENABLE_FIELD_DETECTION_ALARM:
 334                     ipCameraHandler.logger.debug("FieldDetection command");
 335                     ipCameraHandler.sendHttpGET("/ISAPI/Smart/FieldDetection/" + nvrChannel + "01");
 336                     return;
 337                 case CHANNEL_ENABLE_MOTION_ALARM:
 338                     ipCameraHandler
 339                             .sendHttpGET("/ISAPI/System/Video/inputs/channels/" + nvrChannel + "01/motionDetection");
 340                     return;
 341                 case CHANNEL_TEXT_OVERLAY:
 342                     ipCameraHandler
 343                             .sendHttpGET("/ISAPI/System/Video/inputs/channels/" + nvrChannel + "/overlays/text/1");
 344                     return;
 345                 case CHANNEL_ENABLE_EXTERNAL_ALARM_INPUT:
 346                     ipCameraHandler.sendHttpGET("/ISAPI/System/IO/inputs/" + nvrChannel);
 347                     return;
 348                 case CHANNEL_TRIGGER_EXTERNAL_ALARM_INPUT:
 349                     ipCameraHandler.sendHttpGET("/ISAPI/System/IO/inputs/" + nvrChannel);
 350                     return;
 351             }
 352             return; // Return as we have handled the refresh command above and don't need to
 353                     // continue further.
 354         } // end of "REFRESH"
 355         switch (channelUID.getId()) {
 356             case CHANNEL_TEXT_OVERLAY:
 357                 logger.debug("Changing text overlay to {}", command.toString());
 358                 if (command.toString().isEmpty()) {
 359                     hikChangeSetting("/ISAPI/System/Video/inputs/channels/" + nvrChannel + "/overlays/text/1",
 360                             "enabled", "<enabled>false</enabled>");
 361                 } else {
 362                     hikChangeSetting("/ISAPI/System/Video/inputs/channels/" + nvrChannel + "/overlays/text/1",
 363                             "displayText", "<displayText>" + command.toString() + "</displayText>");
 364                     hikChangeSetting("/ISAPI/System/Video/inputs/channels/" + nvrChannel + "/overlays/text/1",
 365                             "enabled", "<enabled>true</enabled>");
 366                 }
 367                 return;
 368             case CHANNEL_ENABLE_EXTERNAL_ALARM_INPUT:
 369                 logger.debug("Changing enabled state of the external input 1 to {}", command.toString());
 370                 if (OnOffType.ON.equals(command)) {
 371                     hikChangeSetting("/ISAPI/System/IO/inputs/" + nvrChannel, "enabled", "<enabled>true</enabled>");
 372                 } else {
 373                     hikChangeSetting("/ISAPI/System/IO/inputs/" + nvrChannel, "enabled", "<enabled>false</enabled>");
 374                 }
 375                 return;
 376             case CHANNEL_TRIGGER_EXTERNAL_ALARM_INPUT:
 377                 logger.debug("Changing triggering state of the external input 1 to {}", command.toString());
 378                 if (OnOffType.OFF.equals(command)) {
 379                     hikChangeSetting("/ISAPI/System/IO/inputs/" + nvrChannel, "triggering",
 380                             "<triggering>low</triggering>");
 381                 } else {
 382                     hikChangeSetting("/ISAPI/System/IO/inputs/" + nvrChannel, "triggering",
 383                             "<triggering>high</triggering>");
 384                 }
 385                 return;
 386             case CHANNEL_ENABLE_PIR_ALARM:
 387                 if (OnOffType.ON.equals(command)) {
 388                     hikChangeSetting("/ISAPI/WLAlarm/PIR", "enabled", "<enabled>true</enabled>");
 389                 } else {
 390                     hikChangeSetting("/ISAPI/WLAlarm/PIR", "enabled", "<enabled>false</enabled>");
 391                 }
 392                 return;
 393             case CHANNEL_ENABLE_AUDIO_ALARM:
 394                 if (OnOffType.ON.equals(command)) {
 395                     hikChangeSetting("/ISAPI/Smart/AudioDetection/channels/" + nvrChannel + "01", "enabled",
 396                             "<enabled>true</enabled>");
 397                 } else {
 398                     hikChangeSetting("/ISAPI/Smart/AudioDetection/channels/" + nvrChannel + "01", "enabled",
 399                             "<enabled>false</enabled>");
 400                 }
 401                 return;
 402             case CHANNEL_ENABLE_LINE_CROSSING_ALARM:
 403                 if (OnOffType.ON.equals(command)) {
 404                     hikChangeSetting("/ISAPI/Smart/LineDetection/" + nvrChannel + "01", "enabled",
 405                             "<enabled>true</enabled>");
 406                 } else {
 407                     hikChangeSetting("/ISAPI/Smart/LineDetection/" + nvrChannel + "01", "enabled",
 408                             "<enabled>false</enabled>");
 409                 }
 410                 return;
 411             case CHANNEL_ENABLE_MOTION_ALARM:
 412                 if (OnOffType.ON.equals(command)) {
 413                     hikChangeSetting("/ISAPI/System/Video/inputs/channels/" + nvrChannel + "01/motionDetection",
 414                             "enabled", "<enabled>true</enabled>");
 415                 } else {
 416                     hikChangeSetting("/ISAPI/System/Video/inputs/channels/" + nvrChannel + "01/motionDetection",
 417                             "enabled", "<enabled>false</enabled>");
 418                 }
 419                 return;
 420             case CHANNEL_ENABLE_FIELD_DETECTION_ALARM:
 421                 if (OnOffType.ON.equals(command)) {
 422                     hikChangeSetting("/ISAPI/Smart/FieldDetection/" + nvrChannel + "01", "enabled",
 423                             "<enabled>true</enabled>");
 424                 } else {
 425                     hikChangeSetting("/ISAPI/Smart/FieldDetection/" + nvrChannel + "01", "enabled",
 426                             "<enabled>false</enabled>");
 427                 }
 428                 return;
 429             case CHANNEL_ACTIVATE_ALARM_OUTPUT:
 430                 if (OnOffType.ON.equals(command)) {
 431                     hikSendXml("/ISAPI/System/IO/outputs/" + nvrChannel + "/trigger",
 432                             "<IOPortData version=\"1.0\" xmlns=\"http://www.hikvision.com/ver10/XMLSchema\">\r\n    <outputState>high</outputState>\r\n</IOPortData>\r\n");
 433                 } else {
 434                     hikSendXml("/ISAPI/System/IO/outputs/" + nvrChannel + "/trigger",
 435                             "<IOPortData version=\"1.0\" xmlns=\"http://www.hikvision.com/ver10/XMLSchema\">\r\n    <outputState>low</outputState>\r\n</IOPortData>\r\n");
 436                 }
 437                 return;
 438         }
 439     }
 440
 441     // If a camera does not need to poll a request as often as snapshots, it can be
 442     // added here. Binding steps through the list.
 443     public ArrayList<String> getLowPriorityRequests() {
 444         ArrayList<String> lowPriorityRequests = new ArrayList<String>(1);
 445         lowPriorityRequests.add("/ISAPI/System/IO/inputs/" + nvrChannel + "/status"); // must stay in element 0.
 446         return lowPriorityRequests;
 447     }
 448 }