# Code coverage report for lib/services/server/informationReporting.js

## Statements: 91.84% (45 / 49) Branches: 100% (0 / 0) Functions: 84.62% (11 / 13) Lines: 91.84% (45 / 49)

All files » lib/services/server/ » informationReporting.js

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     /*
     * Copyright 2014 Telefonica Investigación y Desarrollo, S.A.U
     *
     * This file is part of iotagent-lwm2m-lib
     *
     * iotagent-lwm2m-lib is free software: you can redistribute it and/or
     * modify it under the terms of the GNU Affero General Public License as
     * published by the Free Software Foundation, either version 3 of the License,
     * or (at your option) any later version.
     *
     * iotagent-lwm2m-lib is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     * See the GNU Affero General Public License for more details.
     *
     * You should have received a copy of the GNU Affero General Public
     * License along with iotagent-lwm2m-lib.
     * If not, seehttp://www.gnu.org/licenses/.
     *
     * For those usages not covered by the GNU Affero General Public License
     * please contact with::[contacto@tid.es]
     */

    'use strict';

    var async = require('async'),
        apply = async.apply,
        coapUtils = require('./coapUtils'),
        registry,
        logger = require('logops'),
        context = {
            op: 'LWM2MLib.InformationReporting'
        },
        subscriptions = {},
        _ = require('underscore');

    /**
     * Generates an observer ID from its parts. The ID has the following pattern:
     *
     *   <deviceId>:/<objectType>/<objectId>/<resourceId>
     *
     * @param {Number} deviceId         ID of the device, provided by the LWM2M server.
     * @param {Number} objectType       ID of the object type.
     * @param {Number} objectId         ID of the object instance.
     * @param {Number} resourceId       Observed resource of the object.
     * @returns {string}                The generated ID.
     */
    function buildId(deviceId, objectType, objectId, resourceId) {
        return deviceId + ':/' + objectType + '/' + objectId + '/' + resourceId;
    }

    /**
     * Parse an observer ID, returning its parts encapsulated in an object.
     *
     * @param {String} idString         Observer ID.
     * @returns {{deviceId: string, objectType: string, objectId: string, resourceId: string}}
     */
    function parseId(idString) {
        var fieldList = idString.substring(idString.indexOf(':') + 2).split('/');

        return {
            deviceId: idString.substring(0, idString.indexOf(':')),
            objectType: fieldList[0],
            objectId: fieldList[1],
            resourceId: fieldList[2]
        };
    }

    /**
     * Constructs an object representing the subscription for the changes in the value of a particular resource of a
     * device.
     *
     * @param {Number} deviceId             Internal ID of the device of the subscription (not the endpoint ID).
     * @param {Number} objectType           Number identifying the object type.
     * @param {Number} objectId             Number identifying the object instance.
     * @param {Number} resourceId           Resource of the object to be subscribed to.
     * @param {Object} observeStream        Stream object for writing into.
     * @param {Function} handler            Handler to be called each time a new piece of data arrives.
     * @returns {{id: string, resource: string, deviceId: *, stream: *, dataHandler: Function, finishHandler: Function}}
     * @constructor
     */
    function ResourceListener(deviceId, objectType, objectId, resourceId, observeStream, handler) {
        return {
            id: buildId(deviceId, objectType, objectId, resourceId),
            resource: '/' + objectType + '/' + objectId + '/' + resourceId,
            deviceId: deviceId,
            stream: observeStream,

            dataHandler: function (chunk) {
                logger.debug(context, 'New data on resource /%s/%s/%s in device [%d]',
                    objectType, objectId, resourceId, deviceId);

                handler(chunk.toString('utf8'));
            },

            finishHandler: function(chunk) {
                logger.debug(context, 'Finished observing value of resource /%s/%s/%s in device [%d]',
                    objectType, objectId, resourceId, deviceId);

                delete subscriptions[this.id];
            }
        };
    }

    /**
     * Creates the subscription object and establish the handlers for the incoming data. The first piece of data has a
     * special treatment, as it has to be returned with the callback.
     *
     * @param {Number} deviceId             Internal ID of the device of the subscription (not the endpoint ID).
     * @param {Number} objectType           Number identifying the object type.
     * @param {Number} objectId             Number identifying the object instance.
     * @param {Number} resourceId           Resource of the object to be subscribed to.
     * @param {Function} handler            Handler to be called each time a new piece of data arrives.
     * @param {Object} observeStream        Stream object for writing into.
     */
    function processStream(deviceId, objectType, objectId, resourceId, handler, observeStream, callback) {
        var subscriptionId = buildId(deviceId, objectType, objectId, resourceId);

        observeStream.pause();

        subscriptions[subscriptionId] =
            new ResourceListener(deviceId, objectType, objectId, resourceId, observeStream, handler);

        observeStream.on('data', function (chunk) {
            logger.debug(context, 'Got first piece of data on resource /%s/%s/%s in device [%d]',
                objectType, objectId, resourceId, deviceId);

            observeStream.removeAllListeners('data');
            observeStream.on('data', subscriptions[subscriptionId].dataHandler);
            callback(null, chunk.toString('utf8'));
        });

        observeStream.on('finish', subscriptions[subscriptionId].finishHandler);
        observeStream.resume();
    }

    /**
     * Creates a subscription to a resource in a device, executing the given handler each time new data arrives to the
     * server. As part of the the subscription process, the first piece of data will be automatically resolved in the
     * same way as a Read action (returning the current resource data in the callback). Subsquent data will be processed
     * by the handler.
     *
     * @param {Number} deviceId             Internal ID of the device of the subscription (not the endpoint ID).
     * @param {Number} objectType           Number identifying the object type.
     * @param {Number} objectId             Number identifying the object instance.
     * @param {Number} resourceId           Resource of the object to be subscribed to.
     * @param {Function} handler            Handler to be called each time a new piece of data arrives.
     */
    function observe(deviceId, objectType, objectId, resourceId, handler, callback) {
        function createObserveRequest(obj, callback) {
            var request = {
                host: obj.address,
                port: 5683,
                method: 'GET',
                pathname: '/' + objectType + '/' + objectId + '/' + resourceId,
                observe: true
            };

            callback(null, request);
        }

        logger.debug(context, 'Observing value from resource /%s/%s/%s in device [%d]',
            objectType, objectId, resourceId, deviceId);

        async.waterfall([
            apply(registry.get, deviceId),
            createObserveRequest,
            coapUtils.sendRequest,
            apply(processStream, deviceId, objectType, objectId, resourceId, handler)
        ], callback);
    }

    /**
     * Gets a list of all the subscriptions to client resources actually in use.
     *
     */
    function list(callback) {
        callback(null, _.values(subscriptions));
    }

    /**
     * Remove all the observations the server is currently performing.
     *
     * TODO: completely close the streams instead of simply removing them.
     */
    function clean(callback) {
        subscriptions = {};
        callback();
    }

    /**
     * Cancel an observation for the specified resource in a particular device.
     *
     * @param {Number} deviceId
     * @param {Number} objectType
     * @param {Number} objectId
     * @param {Number} resourceId
     */
    function cancel(deviceId, objectType, objectId, resourceId, callback) {
        var subscriptionId = buildId(deviceId, objectType, objectId, resourceId);

        subscriptions[subscriptionId].stream.close();
        delete subscriptions[subscriptionId];

        callback();
    }

    /**
     * Initializes the Information Reporting interface, specifiying the current device registry to use.
     *
     * @param {Object} deviceRegistry       Device registry in use by the application.
     */
    function init(deviceRegistry) {
        registry = deviceRegistry;
    }

    exports.buildId = buildId;
    exports.parseId = parseId;
    exports.observe = observe;
    exports.list = list;
    exports.clean = clean;
    exports.cancel = cancel;
    exports.init = init;