[Telemetry] Begin adding telemetry handler

Begin adding a general purpose handler for telemetry which
extends on the behavior associated with the telemetrySubscriber
by supporting access to historical data as well. WTD-806.

platform/telemetry/src/TelemetryHandle.js

@@ -0,0 +1,81 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        function TelemetryHandle($q, subscription) {
+            var seriesMap = {},
+                self = Object.create(subscription);
+
+            function requestSeries(telemetryObject, request, callback) {
+                var id = telemetryObject.getId(),
+                    telemetry = telemetryObject.getCapability('telemetry');
+
+                function receiveSeries(series) {
+                    // Store it for subsequent lookup
+                    seriesMap[id] = series;
+                    // Notify callback of new series data, if there is one
+                    if (callback) {
+                        callback(telemetryObject, series);
+                    }
+                    // Pass it along for promise-chaining
+                    return series;
+                }
+
+                // Issue the request via the object's telemetry capability
+                return telemetry.requestData(request).then(receiveSeries);
+            }
+
+
+            /**
+             * Get the most recently obtained telemetry data series associated
+             * with this domain object.
+             * @param {DomainObject} the domain object which has telemetry
+             *        data associated with it
+             * @return {TelemetrySeries} the most recent telemetry series
+             *         (or undefined if there is not one)
+             */
+            self.getSeries = function (domainObject) {
+                var id = domainObject.getId();
+                return seriesMap[id];
+            };
+
+
+            /**
+             * Change the request duration.
+             * @param {object|number} request the duration of historical
+             *        data to look at; or, the request to issue
+             * @param {Function} [callback] a callback that will be
+             *        invoked as new data becomes available, with the
+             *        domain object for which new data is available.
+             */
+            self.request = function (request, callback) {
+                // Issue (and handle) the new request from this object
+                function issueRequest(telemetryObject) {
+                    return requestSeries(telemetryObject, request, callback);
+                }
+
+                // Map the request to all telemetry objects
+                function issueRequests(telemetryObjects) {
+                    return $q.all(telemetryObjects.map(issueRequest));
+                }
+
+                // If the request is a simple number, treat it as a duration
+                request = (typeof request === 'number') ?
+                        { duration: request } : request;
+
+                // Look up telemetry-providing objects from the subscription,
+                // then issue new requests.
+                return subscription.promiseTelemetryObjects()
+                    .then(issueRequests);
+            };
+
+            return self;
+        }
+
+        return TelemetryHandle;
+
+    }
+);