ljm_a0/modules/RTC/DataChannels.js

// cache datachannels to avoid garbage collection
// https://code.google.com/p/chromium/issues/detail?id=405545

var logger = require("jitsi-meet-logger").getLogger(__filename);
var RTCEvents = require("../../service/RTC/RTCEvents");
var GlobalOnErrorHandler = require("../util/GlobalOnErrorHandler");

/**
 * Binds "ondatachannel" event listener to given PeerConnection instance.
 * @param peerConnection WebRTC peer connection instance.
 */
function DataChannels(peerConnection, emitter) {
    peerConnection.ondatachannel = this.onDataChannel.bind(this);
    this.eventEmitter = emitter;

    this._dataChannels = [];

    // Sample code for opening new data channel from Jitsi Meet to the bridge.
    // Although it's not a requirement to open separate channels from both bridge
    // and peer as single channel can be used for sending and receiving data.
    // So either channel opened by the bridge or the one opened here is enough
    // for communication with the bridge.
    /*var dataChannelOptions =
     {
     reliable: true
     };
     var dataChannel
     = peerConnection.createDataChannel("myChannel", dataChannelOptions);

     // Can be used only when is in open state
     dataChannel.onopen = function ()
     {
     dataChannel.send("My channel !!!");
     };
     dataChannel.onmessage = function (event)
     {
     var msgData = event.data;
     logger.info("Got My Data Channel Message:", msgData, dataChannel);
     };*/
}

/**
 * Callback triggered by PeerConnection when new data channel is opened
 * on the bridge.
 * @param event the event info object.
 */
DataChannels.prototype.onDataChannel = function (event) {
    var dataChannel = event.channel;
    var self = this;

    dataChannel.onopen = function () {
        logger.info("Data channel opened by the Videobridge!", dataChannel);

        // Code sample for sending string and/or binary data
        // Sends String message to the bridge
        //dataChannel.send("Hello bridge!");
        // Sends 12 bytes binary message to the bridge
        //dataChannel.send(new ArrayBuffer(12));

        self.eventEmitter.emit(RTCEvents.DATA_CHANNEL_OPEN);
    };

    dataChannel.onerror = function (error) {
        // FIXME: this one seems to be generated a bit too often right now
        // so we are temporarily commenting it before we have more clarity
        // on which of the errors we absolutely need to report
        //GlobalOnErrorHandler.callErrorHandler(
        //        new Error("Data Channel Error:" + error));
        logger.error("Data Channel Error:", error, dataChannel);
    };

    dataChannel.onmessage = function (event) {
        var data = event.data;
        // JSON
        var obj;

        try {
            obj = JSON.parse(data);
        }
        catch (e) {
            GlobalOnErrorHandler.callErrorHandler(e);
            logger.error(
                "Failed to parse data channel message as JSON: ",
                data,
                dataChannel,
                e);
        }
        if (('undefined' !== typeof(obj)) && (null !== obj)) {
            var colibriClass = obj.colibriClass;

            if ("DominantSpeakerEndpointChangeEvent" === colibriClass) {
                // Endpoint ID from the Videobridge.
                var dominantSpeakerEndpoint = obj.dominantSpeakerEndpoint;

                logger.info(
                    "Data channel new dominant speaker event: ",
                    dominantSpeakerEndpoint);
                self.eventEmitter.emit(RTCEvents.DOMINANTSPEAKER_CHANGED, dominantSpeakerEndpoint);
            }
            else if ("InLastNChangeEvent" === colibriClass) {
                var oldValue = obj.oldValue;
                var newValue = obj.newValue;

                // Make sure that oldValue and newValue are of type boolean.
                var type;

                if ((type = typeof oldValue) !== 'boolean') {
                    if (type === 'string') {
                        oldValue = (oldValue == "true");
                    } else {
                        oldValue = new Boolean(oldValue).valueOf();
                    }
                }
                if ((type = typeof newValue) !== 'boolean') {
                    if (type === 'string') {
                        newValue = (newValue == "true");
                    } else {
                        newValue = new Boolean(newValue).valueOf();
                    }
                }

                self.eventEmitter.emit(RTCEvents.LASTN_CHANGED, oldValue, newValue);
            }
            else if ("LastNEndpointsChangeEvent" === colibriClass) {
                // The new/latest list of last-n endpoint IDs.
                var lastNEndpoints = obj.lastNEndpoints;
                // The list of endpoint IDs which are entering the list of
                // last-n at this time i.e. were not in the old list of last-n
                // endpoint IDs.
                var endpointsEnteringLastN = obj.endpointsEnteringLastN;

                logger.info(
                    "Data channel new last-n event: ",
                    lastNEndpoints, endpointsEnteringLastN, obj);
                self.eventEmitter.emit(RTCEvents.LASTN_ENDPOINT_CHANGED,
                    lastNEndpoints, endpointsEnteringLastN, obj);
            } else if("EndpointMessage" === colibriClass) {
                self.eventEmitter.emit(
                    RTCEvents.ENDPOINT_MESSAGE_RECEIVED, obj.from,
                    obj.msgPayload);
            }
            else if ("EndpointConnectivityStatusChangeEvent" === colibriClass) {
                var endpoint = obj.endpoint;
                var isActive = obj.active === "true";
                logger.info("Endpoint connection status changed: " + endpoint
                           + " active ? " + isActive);
                self.eventEmitter.emit(RTCEvents.ENDPOINT_CONN_STATUS_CHANGED,
                    endpoint, isActive);
            }
            else {
                logger.debug("Data channel JSON-formatted message: ", obj);
                // The received message appears to be appropriately formatted
                // (i.e. is a JSON object which assigns a value to the mandatory
                // property colibriClass) so don't just swallow it, expose it to
                // public consumption.
                self.eventEmitter.emit("rtc.datachannel." + colibriClass, obj);
            }
        }
    };

    dataChannel.onclose = function () {
        logger.info("The Data Channel closed", dataChannel);
        var idx = self._dataChannels.indexOf(dataChannel);
        if (idx > -1)
            self._dataChannels = self._dataChannels.splice(idx, 1);
    };
    this._dataChannels.push(dataChannel);
};

/**
 * Closes all currently opened data channels.
 */
DataChannels.prototype.closeAllChannels = function () {
    this._dataChannels.forEach(function (dc){
        // the DC will be removed from the array on 'onclose' event
        dc.close();
    });
};

/**
 * Sends a "selected endpoint changed" message via the data channel.
 * @param endpointId {string} the id of the selected endpoint
 * @throws NetworkError or InvalidStateError from RTCDataChannel#send (@see
 * {@link https://developer.mozilla.org/en-US/docs/Web/API/RTCDataChannel/send})
 * or Error with "No opened data channels found!" message.
 */
DataChannels.prototype.sendSelectedEndpointMessage = function (endpointId) {
    this._onXXXEndpointChanged("selected", endpointId);
};

/**
 * Sends a "pinned endpoint changed" message via the data channel.
 * @param endpointId {string} the id of the pinned endpoint
 * @throws NetworkError or InvalidStateError from RTCDataChannel#send (@see
 * {@link https://developer.mozilla.org/en-US/docs/Web/API/RTCDataChannel/send})
 * or Error with "No opened data channels found!" message.
 */
DataChannels.prototype.sendPinnedEndpointMessage = function (endpointId) {
    this._onXXXEndpointChanged("pinned", endpointId);
};

/**
 * Notifies Videobridge about a change in the value of a specific
 * endpoint-related property such as selected endpoint and pinned endpoint.
 *
 * @param xxx the name of the endpoint-related property whose value changed
 * @param userResource the new value of the endpoint-related property after the
 * change
 * @throws NetworkError or InvalidStateError from RTCDataChannel#send (@see
 * {@link https://developer.mozilla.org/en-US/docs/Web/API/RTCDataChannel/send})
 * or Error with "No opened data channels found!" message.
 */
DataChannels.prototype._onXXXEndpointChanged = function (xxx, userResource) {
    // Derive the correct words from xxx such as selected and Selected, pinned
    // and Pinned.
    var head = xxx.charAt(0);
    var tail = xxx.substring(1);
    var lower = head.toLowerCase() + tail;
    var upper = head.toUpperCase() + tail;
    logger.log(
            'sending ' + lower
                + ' endpoint changed notification to the bridge: ',
            userResource);

    var jsonObject = {};

    jsonObject.colibriClass = (upper + 'EndpointChangedEvent');
    jsonObject[lower + "Endpoint"]
        = (userResource ? userResource : null);

    this.send(jsonObject);

    // Notify Videobridge about the specified endpoint change.
    logger.log(lower + ' endpoint changed: ', userResource);
};

DataChannels.prototype._some = function (callback, thisArg) {
    var dataChannels = this._dataChannels;

    if (dataChannels && dataChannels.length !== 0) {
        if (thisArg)
            return dataChannels.some(callback, thisArg);
        else
            return dataChannels.some(callback);
    } else {
        return false;
    }
};

/**
 * Sends passed object via the first found open datachannel
 * @param jsonObject {object} the object that will be sent
 * @throws NetworkError or InvalidStateError from RTCDataChannel#send (@see
 * {@link https://developer.mozilla.org/en-US/docs/Web/API/RTCDataChannel/send})
 * or Error with "No opened data channels found!" message.
 */
DataChannels.prototype.send = function (jsonObject) {
    if(!this._some(function (dataChannel) {
        if (dataChannel.readyState == 'open') {
                dataChannel.send(JSON.stringify(jsonObject));
            return true;
        }
    })) {
        throw new Error("No opened data channels found!");
    }
};

/**
 * Sends message via the datachannels.
 * @param to {string} the id of the endpoint that should receive the message.
 * If "" the message will be sent to all participants.
 * @param payload {object} the payload of the message.
 * @throws NetworkError or InvalidStateError from RTCDataChannel#send (@see
 * {@link https://developer.mozilla.org/en-US/docs/Web/API/RTCDataChannel/send})
 * or Error with "No opened data channels found!" message.
 */
DataChannels.prototype.sendDataChannelMessage = function (to, payload) {
    this.send({
        colibriClass: "EndpointMessage",
        to: to,
        msgPayload: payload
    });
};

module.exports = DataChannels;