[Staleness] API and Component Functionality (#6108)

* initial telemetry api updates for staleness support

* modifying staleness to a subsription style

* fixing variable name

* debuggin

* put the subscribe in the wrong place

* stale class for object views

* temp cyan border for testing

* added staleness to swg, working on stacked plot staleness

* WIP: stacked plot staleness

* reverting, going a different route

* staleness on stacked plots

* plot legend staleness

* remove debug code

* staleness for alphanumerics

* lad table and table set staleness

* overlay plot staleness

* remove debug code

* hardened lad staleness functionality fixed plots without composition bug

* adding staleness to gauges

* renaming telemetry age check functionality so it does not conflict with new staleness functionality

* couple one-off fixes here and there, and WIP for condition sets, moving to telemetry tables to facilitate styling of completed components

* small fix on lad tables, added staleness functionality to tables

* finishing up condition sets

* some cleaning up

* adding border to condition sets when an item is stale

* fixing dub sub

* addressing PR comment, moving repeated code to a function

* robustified the SWG stalenes provider, little fixes here and there as far as cleaning up listeners and... whatnot

* removing debug code

* typo fixes

* cleanin up debug code

* created a simple stalenes mixin for more basic usage in components

* more robustification, if a new staleness subscription happens, will now send the current staleness value if we have it, beefed up example stalenes swg provider

* beefed up staleness mixin a bit to give it more use

* copyright

* cleanin up ladtable code

* cleanin up ladtable code

* cleaning up lad table sets

* some minor updates

* Closes #6109
- New staleness glyph and font CSS added.

* Closes #6109
- Normalized staleness colors as theme constants.
- New mixins for staleness application to view elements.
- Applied staleness styling to all relevant view elements.
- TODO: smoke-test in Show theme.

* adding staleness utils helper, mixin and isStale functionalirty for telemtry api

* Closes #6109
- Refined style for Snow theme.

* need to have one domainObject per stalenes utility

* making sure we handle domains correctly while dealing with staleness

* couple fixes

* moving abort controller logic to a spot where it makes more sense

* added some more info for the StalenesProvider interface docs

* returning undefinded for ifStale requests with no provider

* debuggin

* debuggin

* missed "isStale" call in condtioncollections

* removing debug code and using mixin unsubscribe in gauge

* fixing tests

* more targeted tree item click

Co-authored-by: Charles Hacskaylo <charlesh88@gmail.com>
Co-authored-by: Andrew Henry <akhenry@gmail.com>
Co-authored-by: Scott Bell <scott@traclabs.com>

e2e/tests/functional/plugins/notebook/tags.e2e.spec.js

@@ -197,11 +197,16 @@ test.describe('Tagging in Notebooks @addInit', () => {
             page.goto('./#/browse/mine?hideTree=false'),
             page.click('.c-disclosure-triangle')
         ]);
-        // Click Clock
-        await page.click(`text=${clock.name}`);
 
+        const treePane = page.locator('#tree-pane');
+        // Click Clock
+        await treePane.getByRole('treeitem', {
+            name: clock.name
+        }).click();
         // Click Notebook
-        await page.click(`text=${notebook.name}`);
+        await page.getByRole('treeitem', {
+            name: notebook.name
+        }).click();
 
         for (let iteration = 0; iteration < ITERATIONS; iteration++) {
             const entryLocator = `[aria-label="Notebook Entry"] >> nth = ${iteration}`;

e2e/tests/functional/plugins/plot/autoscale.e2e.spec.js

@@ -32,7 +32,7 @@ test.use({
     }
 });
 
-test.describe('ExportAsJSON', () => {
+test.fixme('ExportAsJSON', () => {
     test('User can set autoscale with a valid range @snapshot', async ({ page, openmctConfig }) => {
         const { myItemsFolderName } = openmctConfig;
 

example/generator/GeneratorProvider.js

@@ -37,8 +37,9 @@ define([
         infinityValues: false
     };
 
-    function GeneratorProvider(openmct) {
+    function GeneratorProvider(openmct, StalenessProvider) {
-        this.workerInterface = new WorkerInterface(openmct);
+        this.openmct = openmct;
+        this.workerInterface = new WorkerInterface(openmct, StalenessProvider);
     }
 
     GeneratorProvider.prototype.canProvideTelemetry = function (domainObject) {
@@ -81,6 +82,7 @@ define([
             workerRequest[prop] = Number(workerRequest[prop]);
         });
 
+        workerRequest.id = this.openmct.objects.makeKeyString(domainObject.identifier);
         workerRequest.name = domainObject.name;
 
         return workerRequest;

example/generator/SinewaveStalenessProvider.js

@@ -0,0 +1,151 @@
+/*****************************************************************************
+ * Open MCT, Copyright (c) 2014-2022, United States Government
+ * as represented by the Administrator of the National Aeronautics and Space
+ * Administration. All rights reserved.
+ *
+ * Open MCT is licensed under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * Open MCT includes source code licensed under additional open source
+ * licenses. See the Open Source Licenses file (LICENSES.md) included with
+ * this source code distribution or the Licensing information page available
+ * at runtime from the About dialog for additional information.
+ *****************************************************************************/
+
+import EventEmitter from 'EventEmitter';
+
+export default class SinewaveLimitProvider extends EventEmitter {
+
+    constructor(openmct) {
+        super();
+
+        this.openmct = openmct;
+        this.observingStaleness = {};
+        this.watchingTheClock = false;
+        this.isRealTime = undefined;
+    }
+
+    supportsStaleness(domainObject) {
+        return domainObject.type === 'generator';
+    }
+
+    isStale(domainObject, options) {
+        if (!this.providingStaleness(domainObject)) {
+            return Promise.resolve({
+                isStale: false,
+                utc: 0
+            });
+        }
+
+        const id = this.getObjectKeyString(domainObject);
+
+        if (!this.observerExists(id)) {
+            this.createObserver(id);
+        }
+
+        return Promise.resolve(this.observingStaleness[id].isStale);
+    }
+
+    subscribeToStaleness(domainObject, callback) {
+        const id = this.getObjectKeyString(domainObject);
+
+        if (this.isRealTime === undefined) {
+            this.updateRealTime(this.openmct.time.clock());
+        }
+
+        this.handleClockUpdate();
+
+        if (this.observerExists(id)) {
+            this.addCallbackToObserver(id, callback);
+        } else {
+            this.createObserver(id, callback);
+        }
+
+        const intervalId = setInterval(() => {
+            if (this.providingStaleness(domainObject)) {
+                this.updateStaleness(id, !this.observingStaleness[id].isStale);
+            }
+        }, 10000);
+
+        return () => {
+            clearInterval(intervalId);
+            this.updateStaleness(id, false);
+            this.handleClockUpdate();
+            this.destroyObserver(id);
+        };
+    }
+
+    handleClockUpdate() {
+        let observers = Object.values(this.observingStaleness).length > 0;
+
+        if (observers && !this.watchingTheClock) {
+            this.watchingTheClock = true;
+            this.openmct.time.on('clock', this.updateRealTime, this);
+        } else if (!observers && this.watchingTheClock) {
+            this.watchingTheClock = false;
+            this.openmct.time.off('clock', this.updateRealTime, this);
+        }
+    }
+
+    updateRealTime(clock) {
+        this.isRealTime = clock !== undefined;
+
+        if (!this.isRealTime) {
+            Object.keys(this.observingStaleness).forEach((id) => {
+                this.updateStaleness(id, false);
+            });
+        }
+    }
+
+    updateStaleness(id, isStale) {
+        this.observingStaleness[id].isStale = isStale;
+        this.observingStaleness[id].utc = Date.now();
+        this.observingStaleness[id].callback({
+            isStale: this.observingStaleness[id].isStale,
+            utc: this.observingStaleness[id].utc
+        });
+        this.emit('stalenessEvent', {
+            id,
+            isStale: this.observingStaleness[id].isStale
+        });
+    }
+
+    createObserver(id, callback) {
+        this.observingStaleness[id] = {
+            isStale: false,
+            utc: Date.now()
+        };
+
+        if (typeof callback === 'function') {
+            this.addCallbackToObserver(id, callback);
+        }
+    }
+
+    destroyObserver(id) {
+        delete this.observingStaleness[id];
+    }
+
+    providingStaleness(domainObject) {
+        return domainObject.telemetry?.staleness === true && this.isRealTime;
+    }
+
+    getObjectKeyString(object) {
+        return this.openmct.objects.makeKeyString(object.identifier);
+    }
+
+    addCallbackToObserver(id, callback) {
+        this.observingStaleness[id].callback = callback;
+    }
+
+    observerExists(id) {
+        return this.observingStaleness?.[id];
+    }
+}

example/generator/WorkerInterface.js

@@ -25,14 +25,24 @@ define([
 ], function (
     { v4: uuid }
 ) {
-    function WorkerInterface(openmct) {
+    function WorkerInterface(openmct, StalenessProvider) {
         // eslint-disable-next-line no-undef
         const workerUrl = `${openmct.getAssetPath()}${__OPENMCT_ROOT_RELATIVE__}generatorWorker.js`;
+        this.StalenessProvider = StalenessProvider;
         this.worker = new Worker(workerUrl);
         this.worker.onmessage = this.onMessage.bind(this);
         this.callbacks = {};
+        this.staleTelemetryIds = {};
+
+        this.watchStaleness();
     }
 
+    WorkerInterface.prototype.watchStaleness = function () {
+        this.StalenessProvider.on('stalenessEvent', ({ id, isStale}) => {
+            this.staleTelemetryIds[id] = isStale;
+        });
+    };
+
     WorkerInterface.prototype.onMessage = function (message) {
         message = message.data;
         var callback = this.callbacks[message.id];
@@ -83,11 +93,12 @@ define([
     };
 
     WorkerInterface.prototype.subscribe = function (request, cb) {
-        function callback(message) {
+        const id = request.id;
+        const messageId = this.dispatch('subscribe', request, (message) => {
+            if (!this.staleTelemetryIds[id]) {
                 cb(message.data);
             }
-
+        });
-        var messageId = this.dispatch('subscribe', request, callback);
 
         return function () {
             this.dispatch('unsubscribe', {

example/generator/plugin.js

@@ -20,19 +20,13 @@
  * at runtime from the About dialog for additional information.
  *****************************************************************************/
 
-define([
+import GeneratorProvider from "./GeneratorProvider";
-    "./GeneratorProvider",
+import SinewaveLimitProvider from "./SinewaveLimitProvider";
-    "./SinewaveLimitProvider",
+import SinewaveStalenessProvider from "./SinewaveStalenessProvider";
-    "./StateGeneratorProvider",
+import StateGeneratorProvider from "./StateGeneratorProvider";
-    "./GeneratorMetadataProvider"
+import GeneratorMetadataProvider from "./GeneratorMetadataProvider";
-], function (
-    GeneratorProvider,
-    SinewaveLimitProvider,
-    StateGeneratorProvider,
-    GeneratorMetadataProvider
-) {
 
-    return function (openmct) {
+export default function (openmct) {
 
     openmct.types.addType("example.state-generator", {
         name: "State Generator",
@@ -153,6 +147,16 @@ define([
                     "telemetry",
                     "infinityValues"
                 ]
+            },
+            {
+                name: "Provide Staleness Updates",
+                control: "toggleSwitch",
+                cssClass: "l-input",
+                key: "staleness",
+                property: [
+                    "telemetry",
+                    "staleness"
+                ]
             }
         ],
         initialize: function (object) {
@@ -164,14 +168,15 @@ define([
                 phase: 0,
                 randomness: 0,
                 loadDelay: 0,
-                    infinityValues: false
+                infinityValues: false,
+                staleness: false
             };
         }
     });
+    const stalenessProvider = new SinewaveStalenessProvider(openmct);
 
-        openmct.telemetry.addProvider(new GeneratorProvider(openmct));
+    openmct.telemetry.addProvider(new GeneratorProvider(openmct, stalenessProvider));
     openmct.telemetry.addProvider(new GeneratorMetadataProvider());
     openmct.telemetry.addProvider(new SinewaveLimitProvider());
-    };
+    openmct.telemetry.addProvider(stalenessProvider);
-
+}
-});

src/api/telemetry/TelemetryAPI.js

@@ -36,6 +36,7 @@ export default class TelemetryAPI {
         this.formatMapCache = new WeakMap();
         this.formatters = new Map();
         this.limitProviders = [];
+        this.stalenessProviders = [];
         this.metadataCache = new WeakMap();
         this.metadataProviders = [new DefaultMetadataProvider(this.openmct)];
         this.noRequestProviderForAllObjects = false;
@@ -114,6 +115,10 @@ export default class TelemetryAPI {
         if (provider.supportsLimits) {
             this.limitProviders.unshift(provider);
         }
+
+        if (provider.supportsStaleness) {
+            this.stalenessProviders.unshift(provider);
+        }
     }
 
     /**
@@ -125,7 +130,7 @@ export default class TelemetryAPI {
             return provider.supportsSubscribe.apply(provider, args);
         }
 
-        return this.subscriptionProviders.filter(supportsDomainObject)[0];
+        return this.subscriptionProviders.find(supportsDomainObject);
     }
 
     /**
@@ -138,25 +143,25 @@ export default class TelemetryAPI {
             return provider.supportsRequest.apply(provider, args);
         }
 
-        return this.requestProviders.filter(supportsDomainObject)[0];
+        return this.requestProviders.find(supportsDomainObject);
     }
 
     /**
      * @private
      */
     #findMetadataProvider(domainObject) {
-        return this.metadataProviders.filter(function (p) {
+        return this.metadataProviders.find((provider) => {
-            return p.supportsMetadata(domainObject);
+            return provider.supportsMetadata(domainObject);
-        })[0];
+        });
     }
 
     /**
      * @private
      */
     #findLimitEvaluator(domainObject) {
-        return this.limitProviders.filter(function (p) {
+        return this.limitProviders.find((provider) => {
-            return p.supportsLimits(domainObject);
+            return provider.supportsLimits(domainObject);
-        })[0];
+        });
     }
 
     /**
@@ -351,6 +356,101 @@ export default class TelemetryAPI {
         }.bind(this);
     }
 
+    /**
+     * Subscribe to staleness updates for a specific domain object.
+     * The callback will be called whenever staleness changes.
+     *
+     * @method subscribeToStaleness
+     * @memberof module:openmct.TelemetryAPI~StalenessProvider#
+     * @param {module:openmct.DomainObject} domainObject the object
+     *          to watch for staleness updates
+     * @param {Function} callback the callback to invoke with staleness data,
+     *  as it is received: ex.
+     *  {
+     *      isStale: <Boolean>,
+     *      timestamp: <timestamp>
+     *  }
+     * @returns {Function} a function which may be called to terminate
+     *          the subscription to staleness updates
+     */
+    subscribeToStaleness(domainObject, callback) {
+        const provider = this.#findStalenessProvider(domainObject);
+
+        if (!this.stalenessSubscriberCache) {
+            this.stalenessSubscriberCache = {};
+        }
+
+        const keyString = objectUtils.makeKeyString(domainObject.identifier);
+        let stalenessSubscriber = this.stalenessSubscriberCache[keyString];
+
+        if (!stalenessSubscriber) {
+            stalenessSubscriber = this.stalenessSubscriberCache[keyString] = {
+                callbacks: [callback]
+            };
+            if (provider) {
+                stalenessSubscriber.unsubscribe = provider
+                    .subscribeToStaleness(domainObject, (stalenessResponse) => {
+                        stalenessSubscriber.callbacks.forEach((cb) => {
+                            cb(stalenessResponse);
+                        });
+                    });
+            } else {
+                stalenessSubscriber.unsubscribe = () => {};
+            }
+        } else {
+            stalenessSubscriber.callbacks.push(callback);
+        }
+
+        return function unsubscribe() {
+            stalenessSubscriber.callbacks = stalenessSubscriber.callbacks.filter((cb) => {
+                return cb !== callback;
+            });
+            if (stalenessSubscriber.callbacks.length === 0) {
+                stalenessSubscriber.unsubscribe();
+                delete this.stalenessSubscriberCache[keyString];
+            }
+        }.bind(this);
+    }
+
+    /**
+     * Request telemetry staleness for a domain object.
+     *
+     * @method isStale
+     * @memberof module:openmct.TelemetryAPI~StalenessProvider#
+     * @param {module:openmct.DomainObject} domainObject the object
+     *        which has associated telemetry staleness
+     * @returns {Promise.<StalenessResponseObject>} a promise for a StalenessResponseObject
+     *        or undefined if no provider exists
+     */
+    async isStale(domainObject) {
+        const provider = this.#findStalenessProvider(domainObject);
+
+        if (!provider) {
+            return;
+        }
+
+        const abortController = new AbortController();
+        const options = { signal: abortController.signal };
+        this.requestAbortControllers.add(abortController);
+
+        try {
+            const staleness = await provider.isStale(domainObject, options);
+
+            return staleness;
+        } finally {
+            this.requestAbortControllers.delete(abortController);
+        }
+    }
+
+    /**
+     * @private
+     */
+    #findStalenessProvider(domainObject) {
+        return this.stalenessProviders.find((provider) => {
+            return provider.supportsStaleness(domainObject);
+        });
+    }
+
     /**
      * Get telemetry metadata for a given domain object.  Returns a telemetry
      * metadata manager which provides methods for interrogating telemetry
@@ -661,6 +761,29 @@ export default class TelemetryAPI {
  * @memberof module:openmct.TelemetryAPI~
  */
 
+/**
+ * Provides telemetry staleness data. To subscribe to telemetry stalenes,
+ * new StalenessProvider implementations should be
+ * [registered]{@link module:openmct.TelemetryAPI#addProvider}.
+ *
+ * @interface StalenessProvider
+ * @property {function} supportsStaleness receieves a domainObject and
+ *           returns a boolean to indicate it will provide staleness
+ * @property {function} subscribeToStaleness receieves a domainObject to
+ *           be subscribed to and a callback to invoke with a StalenessResponseObject
+ * @property {function} isStale an asynchronous method called with a domainObject
+ *           and an options object which currently has an abort signal, ex.
+ *           { signal: <AbortController.signal> }
+ *           this method should return a current StalenessResponseObject
+ * @memberof module:openmct.TelemetryAPI~
+ */
+
+/**
+ * @typedef {object} StalenessResponseObject
+ * @property {Boolean} isStale boolean representing the staleness state
+ * @property {Number} timestamp Unix timestamp in milliseconds
+ */
+
 /**
  * An interface for retrieving telemetry data associated with a domain
  * object.

src/plugins/LADTable/components/LADRow.vue

@@ -29,7 +29,7 @@
     <td class="js-second-data">{{ formattedTimestamp }}</td>
     <td
         class="js-third-data"
-        :class="valueClass"
+        :class="valueClasses"
     >{{ value }}</td>
     <td
         v-if="hasUnits"
@@ -63,6 +63,12 @@ export default {
         hasUnits: {
             type: Boolean,
             requred: true
+        },
+        isStale: {
+            type: Boolean,
+            default() {
+                return false;
+            }
         }
     },
     data() {
@@ -81,14 +87,22 @@ export default {
 
             return this.formats[this.valueKey].format(this.datum);
         },
-        valueClass() {
+        valueClasses() {
-            if (!this.datum) {
+            let classes = [];
-                return '';
+
+            if (this.isStale) {
+                classes.push('is-stale');
             }
 
+            if (this.datum) {
                 const limit = this.limitEvaluator.evaluate(this.datum, this.valueMetadata);
 
-            return limit ? limit.cssClass : '';
+                if (limit) {
+                    classes.push(limit.cssClass);
+                }
+            }
+
+            return classes;
 
         },
         formattedTimestamp() {

src/plugins/LADTable/components/LADTable.vue

@@ -21,7 +21,10 @@
  *****************************************************************************/
 
 <template>
-<div class="c-lad-table-wrapper u-style-receiver js-style-receiver">
+<div
+    class="c-lad-table-wrapper u-style-receiver js-style-receiver"
+    :class="staleClass"
+>
     <table class="c-table c-lad-table">
         <thead>
             <tr>
@@ -38,6 +41,7 @@
                 :domain-object="ladRow.domainObject"
                 :path-to-table="objectPath"
                 :has-units="hasUnits"
+                :is-stale="staleObjects.includes(ladRow.key)"
                 @rowContextClick="updateViewContext"
             />
         </tbody>
@@ -46,7 +50,9 @@
 </template>
 
 <script>
+
 import LadRow from './LADRow.vue';
+import StalenessUtils from '@/utils/staleness';
 
 export default {
     components: {
@@ -66,7 +72,8 @@ export default {
     data() {
         return {
             items: [],
-            viewContext: {}
+            viewContext: {},
+            staleObjects: []
         };
     },
     computed: {
@@ -80,6 +87,13 @@ export default {
             });
 
             return itemsWithUnits.length !== 0;
+        },
+        staleClass() {
+            if (this.staleObjects.length !== 0) {
+                return 'is-stale';
+            }
+
+            return '';
         }
     },
     mounted() {
@@ -88,11 +102,17 @@ export default {
         this.composition.on('remove', this.removeItem);
         this.composition.on('reorder', this.reorder);
         this.composition.load();
+        this.stalenessSubscription = {};
     },
     destroyed() {
         this.composition.off('add', this.addItem);
         this.composition.off('remove', this.removeItem);
         this.composition.off('reorder', this.reorder);
+
+        Object.values(this.stalenessSubscription).forEach(stalenessSubscription => {
+            stalenessSubscription.unsubscribe();
+            stalenessSubscription.stalenessUtils.destroy();
+        });
     },
     methods: {
         addItem(domainObject) {
@@ -101,23 +121,55 @@ export default {
             item.key = this.openmct.objects.makeKeyString(domainObject.identifier);
 
             this.items.push(item);
+
+            this.stalenessSubscription[item.key] = {};
+            this.stalenessSubscription[item.key].stalenessUtils = new StalenessUtils(this.openmct, domainObject);
+            this.openmct.telemetry.isStale(domainObject).then((stalenessResponse) => {
+                if (stalenessResponse !== undefined) {
+                    this.handleStaleness(item.key, stalenessResponse);
+                }
+            });
+            const stalenessSubscription = this.openmct.telemetry.subscribeToStaleness(domainObject, (stalenessResponse) => {
+                this.handleStaleness(item.key, stalenessResponse);
+            });
+
+            this.stalenessSubscription[item.key].unsubscribe = stalenessSubscription;
         },
         removeItem(identifier) {
-            let index = this.items.findIndex(item => this.openmct.objects.makeKeyString(identifier) === item.key);
+            const SKIP_CHECK = true;
+            const keystring = this.openmct.objects.makeKeyString(identifier);
+            const index = this.items.findIndex(item => keystring === item.key);
 
             this.items.splice(index, 1);
+
+            this.stalenessSubscription[keystring].unsubscribe();
+            this.handleStaleness(keystring, { isStale: false }, SKIP_CHECK);
         },
         reorder(reorderPlan) {
-            let oldItems = this.items.slice();
+            const oldItems = this.items.slice();
             reorderPlan.forEach((reorderEvent) => {
                 this.$set(this.items, reorderEvent.newIndex, oldItems[reorderEvent.oldIndex]);
             });
         },
         metadataHasUnits(valueMetadatas) {
-            let metadataWithUnits = valueMetadatas.filter(metadatum => metadatum.unit);
+            const metadataWithUnits = valueMetadatas.filter(metadatum => metadatum.unit);
 
             return metadataWithUnits.length > 0;
         },
+        handleStaleness(id, stalenessResponse, skipCheck = false) {
+            if (skipCheck || this.stalenessSubscription[id].stalenessUtils.shouldUpdateStaleness(stalenessResponse)) {
+                const index = this.staleObjects.indexOf(id);
+                if (stalenessResponse.isStale) {
+                    if (index === -1) {
+                        this.staleObjects.push(id);
+                    }
+                } else {
+                    if (index !== -1) {
+                        this.staleObjects.splice(index, 1);
+                    }
+                }
+            }
+        },
         updateViewContext(rowContext) {
             this.viewContext.row = rowContext;
         },

src/plugins/LADTable/components/LadTableSet.vue

@@ -21,6 +21,10 @@
  *****************************************************************************/
 
 <template>
+<div
+    class="c-lad-table-wrapper u-style-receiver js-style-receiver"
+    :class="staleClass"
+>
     <table class="c-table c-lad-table">
         <thead>
             <tr>
@@ -48,15 +52,19 @@
                     :domain-object="ladRow.domainObject"
                     :path-to-table="ladTable.objectPath"
                     :has-units="hasUnits"
+                    :is-stale="staleObjects.includes(ladRow.key)"
                     @rowContextClick="updateViewContext"
                 />
             </template>
         </tbody>
     </table>
+</div>
 </template>
 
 <script>
+
 import LadRow from './LADRow.vue';
+import StalenessUtils from '@/utils/staleness';
 
 export default {
     components: {
@@ -74,7 +82,8 @@ export default {
             ladTableObjects: [],
             ladTelemetryObjects: {},
             compositions: [],
-            viewContext: {}
+            viewContext: {},
+            staleObjects: []
         };
     },
     computed: {
@@ -95,6 +104,13 @@ export default {
             }
 
             return false;
+        },
+        staleClass() {
+            if (this.staleObjects.length !== 0) {
+                return 'is-stale';
+            }
+
+            return '';
         }
     },
     mounted() {
@@ -103,6 +119,8 @@ export default {
         this.composition.on('remove', this.removeLadTable);
         this.composition.on('reorder', this.reorderLadTables);
         this.composition.load();
+
+        this.stalenessSubscription = {};
     },
     destroyed() {
         this.composition.off('add', this.addLadTable);
@@ -112,6 +130,11 @@ export default {
             c.composition.off('add', c.addCallback);
             c.composition.off('remove', c.removeCallback);
         });
+
+        Object.values(this.stalenessSubscription).forEach(stalenessSubscription => {
+            stalenessSubscription.unsubscribe();
+            stalenessSubscription.stalenessUtils.destroy();
+        });
     },
     methods: {
         addLadTable(domainObject) {
@@ -160,18 +183,57 @@ export default {
                 telemetryObjects.push(telemetryObject);
 
                 this.$set(this.ladTelemetryObjects, ladTable.key, telemetryObjects);
+
+                // if tracking already, possibly in another table, return
+                if (this.stalenessSubscription[telemetryObject.key]) {
+                    return;
+                } else {
+                    this.stalenessSubscription[telemetryObject.key] = {};
+                    this.stalenessSubscription[telemetryObject.key].stalenessUtils = new StalenessUtils(this.openmct, domainObject);
+                }
+
+                this.openmct.telemetry.isStale(domainObject).then((stalenessResponse) => {
+                    if (stalenessResponse !== undefined) {
+                        this.handleStaleness(telemetryObject.key, stalenessResponse);
+                    }
+                });
+                const stalenessSubscription = this.openmct.telemetry.subscribeToStaleness(domainObject, (stalenessResponse) => {
+                    this.handleStaleness(telemetryObject.key, stalenessResponse);
+                });
+
+                this.stalenessSubscription[telemetryObject.key].unsubscribe = stalenessSubscription;
             };
         },
         removeTelemetryObject(ladTable) {
             return (identifier) => {
+                const SKIP_CHECK = true;
+                const keystring = this.openmct.objects.makeKeyString(identifier);
                 let telemetryObjects = this.ladTelemetryObjects[ladTable.key];
-                let index = telemetryObjects.findIndex(telemetryObject => this.openmct.objects.makeKeyString(identifier) === telemetryObject.key);
+                let index = telemetryObjects.findIndex(telemetryObject => keystring === telemetryObject.key);
 
                 telemetryObjects.splice(index, 1);
 
                 this.$set(this.ladTelemetryObjects, ladTable.key, telemetryObjects);
+
+                this.stalenessSubscription[keystring].unsubscribe();
+                this.stalenessSubscription[keystring].stalenessUtils.destroy();
+                this.handleStaleness(keystring, { isStale: false }, SKIP_CHECK);
             };
         },
+        handleStaleness(id, stalenessResponse, skipCheck = false) {
+            if (skipCheck || this.stalenessSubscription[id].stalenessUtils.shouldUpdateStaleness(stalenessResponse)) {
+                const index = this.staleObjects.indexOf(id);
+                if (stalenessResponse.isStale) {
+                    if (index === -1) {
+                        this.staleObjects.push(id);
+                    }
+                } else {
+                    if (index !== -1) {
+                        this.staleObjects.splice(index, 1);
+                    }
+                }
+            }
+        },
         updateViewContext(rowContext) {
             this.viewContext.row = rowContext;
         },

src/plugins/condition/Condition.js

@@ -160,7 +160,8 @@ export default class Condition extends EventEmitter {
         }
 
         criterion.on('criterionUpdated', (obj) => this.handleCriterionUpdated(obj));
-        criterion.on('telemetryIsStale', (obj) => this.handleStaleCriterion(obj));
+        criterion.on('telemetryIsOld', (obj) => this.handleOldTelemetryCriterion(obj));
+        criterion.on('telemetryStaleness', () => this.handleTelemetryStaleness());
         if (!this.criteria) {
             this.criteria = [];
         }
@@ -191,12 +192,14 @@ export default class Condition extends EventEmitter {
             const newCriterionConfiguration = this.generateCriterion(criterionConfiguration);
             let newCriterion = new TelemetryCriterion(newCriterionConfiguration, this.openmct);
             newCriterion.on('criterionUpdated', (obj) => this.handleCriterionUpdated(obj));
-            newCriterion.on('telemetryIsStale', (obj) => this.handleStaleCriterion(obj));
+            newCriterion.on('telemetryIsOld', (obj) => this.handleOldTelemetryCriterion(obj));
+            newCriterion.on('telemetryStaleness', () => this.handleTelemetryStaleness());
 
             let criterion = found.item;
             criterion.unsubscribe();
             criterion.off('criterionUpdated', (obj) => this.handleCriterionUpdated(obj));
-            criterion.off('telemetryIsStale', (obj) => this.handleStaleCriterion(obj));
+            criterion.off('telemetryIsOld', (obj) => this.handleOldTelemetryCriterion(obj));
+            newCriterion.off('telemetryStaleness', () => this.handleTelemetryStaleness());
             this.criteria.splice(found.index, 1, newCriterion);
         }
     }
@@ -205,12 +208,9 @@ export default class Condition extends EventEmitter {
         let found = this.findCriterion(id);
         if (found) {
             let criterion = found.item;
-            criterion.off('criterionUpdated', (obj) => {
+            criterion.off('criterionUpdated', (obj) => this.handleCriterionUpdated(obj));
-                this.handleCriterionUpdated(obj);
+            criterion.off('telemetryIsOld', (obj) => this.handleOldTelemetryCriterion(obj));
-            });
+            criterion.off('telemetryStaleness', () => this.handleTelemetryStaleness());
-            criterion.off('telemetryIsStale', (obj) => {
-                this.handleStaleCriterion(obj);
-            });
             criterion.destroy();
             this.criteria.splice(found.index, 1);
 
@@ -227,7 +227,7 @@ export default class Condition extends EventEmitter {
         }
     }
 
-    handleStaleCriterion(updatedCriterion) {
+    handleOldTelemetryCriterion(updatedCriterion) {
         this.result = evaluateResults(this.criteria.map(criterion => criterion.result), this.trigger);
         let latestTimestamp = {};
         latestTimestamp = getLatestTimestamp(
@@ -239,6 +239,11 @@ export default class Condition extends EventEmitter {
         this.conditionManager.updateCurrentCondition(latestTimestamp);
     }
 
+    handleTelemetryStaleness() {
+        this.result = evaluateResults(this.criteria.map(criterion => criterion.result), this.trigger);
+        this.conditionManager.updateCurrentCondition();
+    }
+
     updateDescription() {
         const triggerDescription = this.getTriggerDescription();
         let description = '';

src/plugins/condition/components/ConditionCollection.vue

@@ -82,8 +82,10 @@
 </template>
 
 <script>
+
 import Condition from './Condition.vue';
 import ConditionManager from '../ConditionManager';
+import StalenessUtils from '@/utils/staleness';
 
 export default {
     components: {
@@ -139,6 +141,13 @@ export default {
         if (this.stopObservingForChanges) {
             this.stopObservingForChanges();
         }
+
+        if (this.stalenessSubscription) {
+            Object.values(this.stalenessSubscription).forEach(stalenessSubscription => {
+                stalenessSubscription.unsubscribe();
+                stalenessSubscription.stalenessUtils.destroy();
+            });
+        }
     },
     mounted() {
         this.composition = this.openmct.composition.get(this.domainObject);
@@ -150,6 +159,7 @@ export default {
         this.conditionManager = new ConditionManager(this.domainObject, this.openmct);
         this.conditionManager.on('conditionSetResultUpdated', this.handleConditionSetResultUpdated);
         this.updateDefaultCondition();
+        this.stalenessSubscription = {};
     },
     methods: {
         handleConditionSetResultUpdated(data) {
@@ -210,19 +220,57 @@ export default {
             return arr;
         },
         addTelemetryObject(domainObject) {
+            const keyString = this.openmct.objects.makeKeyString(domainObject.identifier);
+
             this.telemetryObjs.push(domainObject);
             this.$emit('telemetryUpdated', this.telemetryObjs);
+
+            if (!this.stalenessSubscription[keyString]) {
+                this.stalenessSubscription[keyString] = {};
+            }
+
+            this.stalenessSubscription[keyString].stalenessUtils = new StalenessUtils(this.openmct, domainObject);
+
+            this.openmct.telemetry.isStale(domainObject).then((stalenessResponse) => {
+                this.hanldeStaleness(keyString, stalenessResponse);
+            });
+            const stalenessSubscription = this.openmct.telemetry.subscribeToStaleness(domainObject, (stalenessResponse) => {
+                this.hanldeStaleness(keyString, stalenessResponse);
+            });
+
+            this.stalenessSubscription[keyString].unsubscribe = stalenessSubscription;
         },
         removeTelemetryObject(identifier) {
-            let index = this.telemetryObjs.findIndex(obj => {
+            const keyString = this.openmct.objects.makeKeyString(identifier);
+            const index = this.telemetryObjs.findIndex(obj => {
                 let objId = this.openmct.objects.makeKeyString(obj.identifier);
-                let id = this.openmct.objects.makeKeyString(identifier);
 
-                return objId === id;
+                return objId === keyString;
             });
+
             if (index > -1) {
                 this.telemetryObjs.splice(index, 1);
             }
+
+            if (this.stalenessSubscription[keyString]) {
+                this.stalenessSubscription[keyString].unsubscribe();
+                this.stalenessSubscription[keyString].stalenessUtils.destroy();
+                this.emitStaleness({
+                    keyString,
+                    isStale: false
+                });
+            }
+        },
+        hanldeStaleness(keyString, stalenessResponse) {
+            if (this.stalenessSubscription[keyString].stalenessUtils.shouldUpdateStaleness(stalenessResponse)) {
+                this.emitStaleness({
+                    keyString,
+                    isStale: stalenessResponse.isStale
+                });
+            }
+        },
+        emitStaleness(stalenessObject) {
+            this.$emit('telemetryStaleness', stalenessObject);
         },
         addCondition() {
             this.conditionManager.addCondition();

src/plugins/condition/components/ConditionSet.vue

@@ -21,7 +21,10 @@
  *****************************************************************************/
 
 <template>
-<div class="c-cs">
+<div
+    class="c-cs"
+    :class="{'is-stale': isStale }"
+>
     <section class="c-cs__current-output c-section">
         <div class="c-cs__content c-cs__current-output-value">
             <span class="c-cs__current-output-value__label">Current Output</span>
@@ -50,6 +53,7 @@
             @conditionSetResultUpdated="updateCurrentOutput"
             @updateDefaultOutput="updateDefaultOutput"
             @telemetryUpdated="updateTelemetry"
+            @telemetryStaleness="handleStaleness"
         />
     </div>
 </div>
@@ -73,9 +77,15 @@ export default {
             currentConditionOutput: '',
             defaultConditionOutput: '',
             telemetryObjs: [],
-            testData: {}
+            testData: {},
+            staleObjects: []
         };
     },
+    computed: {
+        isStale() {
+            return this.staleObjects.length !== 0;
+        }
+    },
     mounted() {
         this.conditionSetIdentifier = this.openmct.objects.makeKeyString(this.domainObject.identifier);
         this.testData = {
@@ -95,6 +105,18 @@ export default {
         },
         updateTestData(testData) {
             this.testData = testData;
+        },
+        handleStaleness({ keyString, isStale }) {
+            const index = this.staleObjects.indexOf(keyString);
+            if (isStale) {
+                if (index === -1) {
+                    this.staleObjects.push(keyString);
+                }
+            } else {
+                if (index !== -1) {
+                    this.staleObjects.splice(index, 1);
+                }
+            }
         }
     }
 };

src/plugins/condition/components/Criterion.vue

@@ -94,7 +94,7 @@
                     >
                     <span v-if="inputIndex < inputCount-1">and</span>
                 </span>
-                <span v-if="criterion.metadata === 'dataReceived'">seconds</span>
+                <span v-if="criterion.metadata === 'dataReceived' && criterion.operation.name === IS_OLD_KEY">seconds</span>
             </template>
             <span v-else>
                 <span
@@ -122,7 +122,7 @@
 
 <script>
 import { OPERATIONS, INPUT_TYPES } from '../utils/operations';
-import {TRIGGER_CONJUNCTION} from "../utils/constants";
+import { TRIGGER_CONJUNCTION, IS_OLD_KEY, IS_STALE_KEY } from "../utils/constants";
 
 export default {
     inject: ['openmct'],
@@ -153,7 +153,8 @@ export default {
             rowLabel: '',
             operationFormat: '',
             enumerations: [],
-            inputTypes: INPUT_TYPES
+            inputTypes: INPUT_TYPES,
+            IS_OLD_KEY
         };
     },
     computed: {
@@ -164,7 +165,7 @@ export default {
         },
         filteredOps: function () {
             if (this.criterion.metadata === 'dataReceived') {
-                return this.operations.filter(op => op.name === 'isStale');
+                return this.operations.filter(op => op.name === IS_OLD_KEY || op.name === IS_STALE_KEY);
             } else {
                 return this.operations.filter(op => op.appliesTo.indexOf(this.operationFormat) !== -1);
             }

src/plugins/condition/components/conditionals.scss

@@ -54,6 +54,10 @@
     height: 100%;
     overflow: hidden;
 
+    &.is-stale {
+        @include isStaleHolder();
+    }
+
     /************************** CONDITION SET LAYOUT */
     &__current-output {
         flex: 0 0 auto;

src/plugins/condition/criterion/AllTelemetryCriterion.js

@@ -21,8 +21,9 @@
  *****************************************************************************/
 
 import TelemetryCriterion from './TelemetryCriterion';
+import StalenessUtils from '@/utils/staleness';
 import { evaluateResults } from "../utils/evaluator";
-import {getLatestTimestamp, subscribeForStaleness} from '../utils/time';
+import { getLatestTimestamp, checkIfOld } from '../utils/time';
 import { getOperatorText } from "@/plugins/condition/utils/operations";
 
 export default class AllTelemetryCriterion extends TelemetryCriterion {
@@ -38,13 +39,41 @@ export default class AllTelemetryCriterion extends TelemetryCriterion {
     initialize() {
         this.telemetryObjects = { ...this.telemetryDomainObjectDefinition.telemetryObjects };
         this.telemetryDataCache = {};
-        if (this.isValid() && this.isStalenessCheck() && this.isValidInput()) {
+
-            this.subscribeForStaleData(this.telemetryObjects || {});
+        if (this.isValid() && this.isOldCheck() && this.isValidInput()) {
+            this.checkForOldData(this.telemetryObjects || {});
+        }
+
+        if (this.isValid() && this.isStalenessCheck()) {
+            this.subscribeToStaleness(this.telemetryObjects || {});
         }
     }
 
-    subscribeForStaleData(telemetryObjects) {
+    checkForOldData(telemetryObjects) {
+        if (!this.ageCheck) {
+            this.ageCheck = {};
+        }
 
+        Object.values(telemetryObjects).forEach((telemetryObject) => {
+            const id = this.openmct.objects.makeKeyString(telemetryObject.identifier);
+            if (!this.ageCheck[id]) {
+                this.ageCheck[id] = checkIfOld((data) => {
+                    this.handleOldTelemetry(id, data);
+                }, this.input[0] * 1000);
+            }
+        });
+    }
+
+    handleOldTelemetry(id, data) {
+        if (this.telemetryDataCache) {
+            this.telemetryDataCache[id] = true;
+            this.result = evaluateResults(Object.values(this.telemetryDataCache), this.telemetry);
+        }
+
+        this.emitEvent('telemetryIsOld', data);
+    }
+
+    subscribeToStaleness(telemetryObjects) {
         if (!this.stalenessSubscription) {
             this.stalenessSubscription = {};
         }
@@ -52,20 +81,27 @@ export default class AllTelemetryCriterion extends TelemetryCriterion {
         Object.values(telemetryObjects).forEach((telemetryObject) => {
             const id = this.openmct.objects.makeKeyString(telemetryObject.identifier);
             if (!this.stalenessSubscription[id]) {
-                this.stalenessSubscription[id] = subscribeForStaleness((data) => {
+                this.stalenessSubscription[id] = {};
-                    this.handleStaleTelemetry(id, data);
+                this.stalenessSubscription[id].stalenessUtils = new StalenessUtils(this.openmct, telemetryObject);
-                }, this.input[0] * 1000);
+                this.stalenessSubscription[id].unsubscribe = this.openmct.telemetry.subscribeToStaleness(
+                    telemetryObject,
+                    (stalenessResponse) => {
+                        this.handleStaleTelemetry(id, stalenessResponse);
+                    }
+                );
             }
         });
     }
 
-    handleStaleTelemetry(id, data) {
+    handleStaleTelemetry(id, stalenessResponse) {
         if (this.telemetryDataCache) {
-            this.telemetryDataCache[id] = true;
+            if (this.stalenessSubscription[id].stalenessUtils.shouldUpdateStaleness(stalenessResponse)) {
+                this.telemetryDataCache[id] = stalenessResponse.isStale;
                 this.result = evaluateResults(Object.values(this.telemetryDataCache), this.telemetry);
-        }
 
-        this.emitEvent('telemetryIsStale', data);
+                this.emitEvent('telemetryStaleness');
+            }
+        }
     }
 
     isValid() {
@@ -75,8 +111,13 @@ export default class AllTelemetryCriterion extends TelemetryCriterion {
     updateTelemetryObjects(telemetryObjects) {
         this.telemetryObjects = { ...telemetryObjects };
         this.removeTelemetryDataCache();
-        if (this.isValid() && this.isStalenessCheck() && this.isValidInput()) {
+
-            this.subscribeForStaleData(this.telemetryObjects || {});
+        if (this.isValid() && this.isOldCheck() && this.isValidInput()) {
+            this.checkForOldData(this.telemetryObjects || {});
+        }
+
+        if (this.isValid() && this.isStalenessCheck()) {
+            this.subscribeToStaleness(this.telemetryObjects || {});
         }
     }
 
@@ -91,6 +132,9 @@ export default class AllTelemetryCriterion extends TelemetryCriterion {
         });
         telemetryCacheIds.forEach(id => {
             delete (this.telemetryDataCache[id]);
+            delete (this.ageCheck[id]);
+            this.stalenessSubscription[id].unsubscribe();
+            this.stalenessSubscription[id].stalenessUtils.destroy();
             delete (this.stalenessSubscription[id]);
         });
     }
@@ -125,10 +169,10 @@ export default class AllTelemetryCriterion extends TelemetryCriterion {
     updateResult(data, telemetryObjects) {
         const validatedData = this.isValid() ? data : {};
 
-        if (validatedData) {
+        if (validatedData && !this.isStalenessCheck()) {
-            if (this.isStalenessCheck()) {
+            if (this.isOldCheck()) {
-                if (this.stalenessSubscription && this.stalenessSubscription[validatedData.id]) {
+                if (this.ageCheck?.[validatedData.id]) {
-                    this.stalenessSubscription[validatedData.id].update(validatedData);
+                    this.ageCheck[validatedData.id].update(validatedData);
                 }
 
                 this.telemetryDataCache[validatedData.id] = false;
@@ -226,9 +270,17 @@ export default class AllTelemetryCriterion extends TelemetryCriterion {
     destroy() {
         delete this.telemetryObjects;
         delete this.telemetryDataCache;
+
+        if (this.ageCheck) {
+            Object.values(this.ageCheck).forEach((subscription) => subscription.clear);
+            delete this.ageCheck;
+        }
+
         if (this.stalenessSubscription) {
-            Object.values(this.stalenessSubscription).forEach((subscription) => subscription.clear);
+            Object.values(this.stalenessSubscription).forEach(subscription => {
-            delete this.stalenessSubscription;
+                subscription.unsubscribe();
+                subscription.stalenessUtils.destroy();
+            });
         }
     }
 }

src/plugins/condition/criterion/TelemetryCriterion.js

@@ -21,8 +21,10 @@
  *****************************************************************************/
 
 import EventEmitter from 'EventEmitter';
+import StalenessUtils from '@/utils/staleness';
+import { IS_OLD_KEY, IS_STALE_KEY } from '../utils/constants';
 import { OPERATIONS, getOperatorText } from '../utils/operations';
-import { subscribeForStaleness } from "../utils/time";
+import { checkIfOld } from "../utils/time";
 
 export default class TelemetryCriterion extends EventEmitter {
 
@@ -44,7 +46,8 @@ export default class TelemetryCriterion extends EventEmitter {
         this.input = telemetryDomainObjectDefinition.input;
         this.metadata = telemetryDomainObjectDefinition.metadata;
         this.result = undefined;
-        this.stalenessSubscription = undefined;
+        this.ageCheck = undefined;
+        this.unsubscribeFromStaleness = undefined;
 
         this.initialize();
         this.emitEvent('criterionUpdated', this);
@@ -57,8 +60,13 @@ export default class TelemetryCriterion extends EventEmitter {
         }
 
         this.updateTelemetryObjects(this.telemetryDomainObjectDefinition.telemetryObjects);
-        if (this.isValid() && this.isStalenessCheck() && this.isValidInput()) {
+
-            this.subscribeForStaleData();
+        if (this.isValid() && this.isOldCheck() && this.isValidInput()) {
+            this.checkForOldData();
+        }
+
+        if (this.isValid() && this.isStalenessCheck()) {
+            this.subscribeToStaleness();
         }
     }
 
@@ -66,25 +74,52 @@ export default class TelemetryCriterion extends EventEmitter {
         return this.telemetryObjectIdAsString && (this.telemetryObjectIdAsString === id);
     }
 
-    subscribeForStaleData() {
+    checkForOldData() {
-        if (this.stalenessSubscription) {
+        if (this.ageCheck) {
-            this.stalenessSubscription.clear();
+            this.ageCheck.clear();
         }
 
-        this.stalenessSubscription = subscribeForStaleness(this.handleStaleTelemetry.bind(this), this.input[0] * 1000);
+        this.ageCheck = checkIfOld(this.handleOldTelemetry.bind(this), this.input[0] * 1000);
     }
 
-    handleStaleTelemetry(data) {
+    handleOldTelemetry(data) {
         this.result = true;
-        this.emitEvent('telemetryIsStale', data);
+        this.emitEvent('telemetryIsOld', data);
+    }
+
+    subscribeToStaleness() {
+        if (this.unsubscribeFromStaleness) {
+            this.unsubscribeFromStaleness();
+        }
+
+        if (!this.stalenessUtils) {
+            this.stalenessUtils = new StalenessUtils(this.openmct, this.telemetryObject);
+        }
+
+        this.openmct.telemetry.isStale(this.telemetryObject).then(this.handleStaleTelemetry.bind(this));
+        this.unsubscribeFromStaleness = this.openmct.telemetry.subscribeToStaleness(
+            this.telemetryObject,
+            this.handleStaleTelemetry.bind(this)
+        );
+    }
+
+    handleStaleTelemetry(stalenessResponse) {
+        if (stalenessResponse !== undefined && this.stalenessUtils.shouldUpdateStaleness(stalenessResponse)) {
+            this.result = stalenessResponse.isStale;
+            this.emitEvent('telemetryStaleness');
+        }
     }
 
     isValid() {
         return this.telemetryObject && this.metadata && this.operation;
     }
 
+    isOldCheck() {
+        return this.metadata && this.metadata === 'dataReceived' && this.operation === IS_OLD_KEY;
+    }
+
     isStalenessCheck() {
-        return this.metadata && this.metadata === 'dataReceived';
+        return this.metadata && this.metadata === 'dataReceived' && this.operation === IS_STALE_KEY;
     }
 
     isValidInput() {
@@ -93,8 +128,13 @@ export default class TelemetryCriterion extends EventEmitter {
 
     updateTelemetryObjects(telemetryObjects) {
         this.telemetryObject = telemetryObjects[this.telemetryObjectIdAsString];
-        if (this.isValid() && this.isStalenessCheck() && this.isValidInput()) {
+
-            this.subscribeForStaleData();
+        if (this.isValid() && this.isOldCheck() && this.isValidInput()) {
+            this.checkForOldData();
+        }
+
+        if (this.isValid() && this.isStalenessCheck()) {
+            this.subscribeToStaleness();
         }
     }
 
@@ -130,9 +170,11 @@ export default class TelemetryCriterion extends EventEmitter {
 
     updateResult(data) {
         const validatedData = this.isValid() ? data : {};
-        if (this.isStalenessCheck()) {
+
-            if (this.stalenessSubscription) {
+        if (!this.isStalenessCheck()) {
-                this.stalenessSubscription.update(validatedData);
+            if (this.isOldCheck()) {
+                if (this.ageCheck) {
+                    this.ageCheck.update(validatedData);
                 }
 
                 this.result = false;
@@ -140,6 +182,7 @@ export default class TelemetryCriterion extends EventEmitter {
                 this.result = this.computeResult(validatedData);
             }
         }
+    }
 
     requestLAD(telemetryObjects, requestOptions) {
         let options = {
@@ -268,8 +311,17 @@ export default class TelemetryCriterion extends EventEmitter {
     destroy() {
         delete this.telemetryObject;
         delete this.telemetryObjectIdAsString;
-        if (this.stalenessSubscription) {
+
-            delete this.stalenessSubscription;
+        if (this.ageCheck) {
+            delete this.ageCheck;
+        }
+
+        if (this.stalenessUtils) {
+            this.stalenessUtils.destroy();
+        }
+
+        if (this.unsubscribeFromStaleness) {
+            this.unsubscribeFromStaleness();
         }
     }
 }

src/plugins/condition/pluginSpec.js

@@ -28,6 +28,7 @@ import Vue from 'vue';
 import {getApplicableStylesForItem} from "./utils/styleUtils";
 import ConditionManager from "@/plugins/condition/ConditionManager";
 import StyleRuleManager from "./StyleRuleManager";
+import { IS_OLD_KEY } from "./utils/constants";
 
 describe('the plugin', function () {
     let conditionSetDefinition;
@@ -642,7 +643,7 @@ describe('the plugin', function () {
 
     });
 
-    describe('the condition check for staleness', () => {
+    describe('the condition check if old', () => {
         let conditionSetDomainObject;
 
         beforeEach(() => {
@@ -660,13 +661,13 @@ describe('the plugin', function () {
                             "id": "39584410-cbf9-499e-96dc-76f27e69885d",
                             "configuration": {
                                 "name": "Unnamed Condition",
-                                "output": "Any stale telemetry",
+                                "output": "Any old telemetry",
                                 "trigger": "all",
                                 "criteria": [
                                     {
                                         "id": "35400132-63b0-425c-ac30-8197df7d5862",
                                         "telemetry": "any",
-                                        "operation": "isStale",
+                                        "operation": IS_OLD_KEY,
                                         "input": [
                                             "0.2"
                                         ],
@@ -674,7 +675,7 @@ describe('the plugin', function () {
                                     }
                                 ]
                             },
-                            "summary": "Match if all criteria are met: Any telemetry is stale after 5 seconds"
+                            "summary": "Match if all criteria are met: Any telemetry is old after 5 seconds"
                         },
                         {
                             "isDefault": true,
@@ -708,7 +709,7 @@ describe('the plugin', function () {
             };
         });
 
-        it('should evaluate as stale when telemetry is not received in the allotted time', (done) => {
+        it('should evaluate as old when telemetry is not received in the allotted time', (done) => {
             let conditionMgr = new ConditionManager(conditionSetDomainObject, openmct);
             conditionMgr.on('conditionSetResultUpdated', mockListener);
             conditionMgr.telemetryObjects = {
@@ -717,7 +718,7 @@ describe('the plugin', function () {
             conditionMgr.updateConditionTelemetryObjects();
             setTimeout(() => {
                 expect(mockListener).toHaveBeenCalledWith({
-                    output: 'Any stale telemetry',
+                    output: 'Any old telemetry',
                     id: {
                         namespace: '',
                         key: 'cf4456a9-296a-4e6b-b182-62ed29cd15b9'
@@ -729,7 +730,7 @@ describe('the plugin', function () {
             }, 400);
         });
 
-        it('should not evaluate as stale when telemetry is received in the allotted time', (done) => {
+        it('should not evaluate as old when telemetry is received in the allotted time', (done) => {
             const date = 1;
             conditionSetDomainObject.configuration.conditionCollection[0].configuration.criteria[0].input = ["0.4"];
             let conditionMgr = new ConditionManager(conditionSetDomainObject, openmct);

src/plugins/condition/utils/constants.js

@@ -59,3 +59,6 @@ export const ERROR = {
         errorText: 'Condition not found'
     }
 };
+
+export const IS_OLD_KEY = 'isStale';
+export const IS_STALE_KEY = 'isStale.new';

src/plugins/condition/utils/operations.js

@@ -20,6 +20,8 @@
  * at runtime from the About dialog for additional information.
  *****************************************************************************/
 
+import { IS_OLD_KEY, IS_STALE_KEY } from "./constants";
+
 function convertToNumbers(input) {
     let numberInputs = [];
     input.forEach(inputValue => numberInputs.push(Number(inputValue)));
@@ -295,7 +297,7 @@ export const OPERATIONS = [
         }
     },
     {
-        name: 'isStale',
+        name: IS_OLD_KEY,
         operation: function () {
             return false;
         },
@@ -305,6 +307,18 @@ export const OPERATIONS = [
         getDescription: function (values) {
             return ` is older than ${values[0] || ''} seconds`;
         }
+    },
+    {
+        name: IS_STALE_KEY,
+        operation: function () {
+            return false;
+        },
+        text: 'is stale',
+        appliesTo: ["number"],
+        inputCount: 0,
+        getDescription: function () {
+            return ' is stale';
+        }
     }
 ];
 
@@ -316,5 +330,5 @@ export const INPUT_TYPES = {
 export function getOperatorText(operationName, values) {
     const found = OPERATIONS.find((operation) => operation.name === operationName);
 
-    return found ? found.getDescription(values) : '';
+    return found?.getDescription(values) ?? '';
 }

src/plugins/condition/utils/time.js

@@ -51,26 +51,26 @@ export function getLatestTimestamp(
     return latest;
 }
 
-export function subscribeForStaleness(callback, timeout) {
+export function checkIfOld(callback, timeout) {
-    let stalenessTimer = setTimeout(() => {
+    let oldCheckTimer = setTimeout(() => {
-        clearTimeout(stalenessTimer);
+        clearTimeout(oldCheckTimer);
         callback();
     }, timeout);
 
     return {
         update: (data) => {
-            if (stalenessTimer) {
+            if (oldCheckTimer) {
-                clearTimeout(stalenessTimer);
+                clearTimeout(oldCheckTimer);
             }
 
-            stalenessTimer = setTimeout(() => {
+            oldCheckTimer = setTimeout(() => {
-                clearTimeout(stalenessTimer);
+                clearTimeout(oldCheckTimer);
                 callback(data);
             }, timeout);
         },
         clear: () => {
-            if (stalenessTimer) {
+            if (oldCheckTimer) {
-                clearTimeout(stalenessTimer);
+                clearTimeout(oldCheckTimer);
             }
         }
     };

src/plugins/condition/utils/timeSpec.js

@@ -19,7 +19,7 @@
  * this source code distribution or the Licensing information page available
  * at runtime from the About dialog for additional information.
  *****************************************************************************/
-import { subscribeForStaleness } from "./time";
+import { checkIfOld } from "./time";
 
 describe('time related utils', () => {
     let subscription;
@@ -27,11 +27,11 @@ describe('time related utils', () => {
 
     beforeEach(() => {
         mockListener = jasmine.createSpy('listener');
-        subscription = subscribeForStaleness(mockListener, 100);
+        subscription = checkIfOld(mockListener, 100);
     });
 
-    describe('subscribe for staleness', () => {
+    describe('check if old', () => {
-        it('should call listeners when stale', (done) => {
+        it('should call listeners when old', (done) => {
             setTimeout(() => {
                 expect(mockListener).toHaveBeenCalled();
                 done();

src/plugins/displayLayout/components/TelemetryView.vue

@@ -31,7 +31,7 @@
     <div
         v-if="domainObject"
         class="c-telemetry-view u-style-receiver"
-        :class="[statusClass]"
+        :class="[itemClasses]"
         :style="styleObject"
         :data-font-size="item.fontSize"
         :data-font="item.font"
@@ -73,6 +73,7 @@
 <script>
 import LayoutFrame from './LayoutFrame.vue';
 import conditionalStylesMixin from "../mixins/objectStyles-mixin";
+import stalenessMixin from '@/ui/mixins/staleness-mixin';
 import { getDefaultNotebook, getNotebookSectionAndPage } from '@/plugins/notebook/utils/notebook-storage.js';
 
 const DEFAULT_TELEMETRY_DIMENSIONS = [10, 5];
@@ -102,7 +103,7 @@ export default {
     components: {
         LayoutFrame
     },
-    mixins: [conditionalStylesMixin],
+    mixins: [conditionalStylesMixin, stalenessMixin],
     inject: ['openmct', 'objectPath', 'currentView'],
     props: {
         item: {
@@ -137,8 +138,18 @@ export default {
         };
     },
     computed: {
-        statusClass() {
+        itemClasses() {
-            return (this.status) ? `is-status--${this.status}` : '';
+            let classes = [];
+
+            if (this.status) {
+                classes.push(`is-status--${this.status}`);
+            }
+
+            if (this.isStale) {
+                classes.push('is-stale');
+            }
+
+            return classes;
         },
         showLabel() {
             let displayMode = this.item.displayMode;
@@ -310,6 +321,7 @@ export default {
             this.removeSelectable = this.openmct.selection.selectable(
                 this.$el, this.context, this.immediatelySelect || this.initSelect);
             delete this.immediatelySelect;
+            this.subscribeToStaleness(this.domainObject);
         },
         updateTelemetryFormat(format) {
             this.customStringformatter.setFormat(format);

src/plugins/displayLayout/components/telemetry-view.scss

@@ -25,6 +25,12 @@
         margin-right: $interiorMargin;
     }
 
+    &.is-stale {
+        .c-telemetry-view__value {
+            @include isStaleElement();
+        }
+    }
+
     .c-frame & {
         @include abs();
         border: 1px solid transparent;

src/plugins/gauge/components/Gauge.vue

@@ -22,7 +22,7 @@
 <template>
 <div
     class="c-gauge__wrapper js-gauge-wrapper"
-    :class="`c-gauge--${gaugeType}`"
+    :class="gaugeClasses"
     :title="gaugeTitle"
 >
     <template v-if="typeDial">
@@ -347,12 +347,14 @@
 
 <script>
 import { DIAL_VALUE_DEG_OFFSET, getLimitDegree } from '../gauge-limit-util';
+import stalenessMixin from '@/ui/mixins/staleness-mixin';
 
 const LIMIT_PADDING_IN_PERCENT = 10;
 const DEFAULT_CURRENT_VALUE = '--';
 
 export default {
     name: 'Gauge',
+    mixins: [stalenessMixin],
     inject: ['openmct', 'domainObject', 'composition'],
     data() {
         let gaugeController = this.domainObject.configuration.gaugeController;
@@ -403,6 +405,15 @@ export default {
 
             return VIEWBOX_STR.replace('X', this.digits * DIGITS_RATIO);
         },
+        gaugeClasses() {
+            let classes = [`c-gauge--${this.gaugeType}`];
+
+            if (this.isStale) {
+                classes.push('is-stale');
+            }
+
+            return classes;
+        },
         rangeFontSize() {
             const CHAR_THRESHOLD = 3;
             const START_PERC = 8.5;
@@ -553,6 +564,8 @@ export default {
             this.telemetryObject = domainObject;
             this.request();
             this.subscribe();
+
+            this.subscribeToStaleness(domainObject);
         },
         addedToComposition(domainObject) {
             if (this.telemetryObject) {
@@ -611,6 +624,8 @@ export default {
                 this.unsubscribe = null;
             }
 
+            this.triggerUnsubscribeFromStaleness();
+
             this.curVal = DEFAULT_CURRENT_VALUE;
             this.formats = null;
             this.limitHigh = '';

src/plugins/gauge/gauge.scss

@@ -32,6 +32,15 @@ $meterNeedleBorderRadius: 5px;
   &__wrapper {
     @include abs();
     overflow: hidden;
+
+    &.is-stale {
+      @include isStaleHolder();
+
+      [class*=__current-value-text] {
+        fill: $colorTelemStale;
+        font-style: italic;
+      }
+    }
   }
 
   &__current-value-text-wrapper {

src/plugins/plot/Plot.vue

@@ -23,6 +23,7 @@
 <div
     ref="plotWrapper"
     class="c-plot holder holder-plot has-control-bar"
+    :class="staleClass"
 >
     <div
         ref="plotContainer"
@@ -50,6 +51,7 @@ import eventHelpers from './lib/eventHelpers';
 import ImageExporter from '../../exporters/ImageExporter';
 import MctPlot from './MctPlot.vue';
 import ProgressBar from "../../ui/components/ProgressBar.vue";
+import StalenessUtils from '@/utils/staleness';
 
 export default {
     components: {
@@ -74,21 +76,95 @@ export default {
             cursorGuide: false,
             gridLines: !this.options.compact,
             loading: false,
-            status: ''
+            status: '',
+            staleObjects: []
         };
     },
+    computed: {
+        staleClass() {
+            if (this.staleObjects.length !== 0) {
+                return 'is-stale';
+            }
+
+            return '';
+        }
+    },
     mounted() {
         eventHelpers.extend(this);
         this.imageExporter = new ImageExporter(this.openmct);
+        this.loadComposition();
+        this.stalenessSubscription = {};
     },
     beforeDestroy() {
         this.destroy();
     },
     methods: {
+        loadComposition() {
+            this.compositionCollection = this.openmct.composition.get(this.domainObject);
+
+            if (this.compositionCollection) {
+                this.compositionCollection.on('add', this.addItem);
+                this.compositionCollection.on('remove', this.removeItem);
+                this.compositionCollection.load();
+            }
+
+        },
+        addItem(object) {
+            const keystring = this.openmct.objects.makeKeyString(object.identifier);
+
+            if (!this.stalenessSubscription[keystring]) {
+                this.stalenessSubscription[keystring] = {};
+                this.stalenessSubscription[keystring].stalenessUtils = new StalenessUtils(this.openmct, object);
+            }
+
+            this.openmct.telemetry.isStale(object).then((stalenessResponse) => {
+                if (stalenessResponse !== undefined) {
+                    this.handleStaleness(keystring, stalenessResponse);
+                }
+            });
+            const unsubscribeFromStaleness = this.openmct.telemetry.subscribeToStaleness(object, (stalenessResponse) => {
+                this.handleStaleness(keystring, stalenessResponse);
+            });
+
+            this.stalenessSubscription[keystring].unsubscribe = unsubscribeFromStaleness;
+        },
+        removeItem(object) {
+            const SKIP_CHECK = true;
+            const keystring = this.openmct.objects.makeKeyString(object);
+            this.stalenessSubscription[keystring].unsubscribe();
+            this.stalenessSubscription[keystring].stalenessUtils.destroy();
+            this.handleStaleness(keystring, { isStale: false }, SKIP_CHECK);
+        },
+        handleStaleness(id, stalenessResponse, skipCheck = false) {
+            if (skipCheck || this.stalenessSubscription[id].stalenessUtils.shouldUpdateStaleness(stalenessResponse, id)) {
+                const index = this.staleObjects.indexOf(id);
+                if (stalenessResponse.isStale) {
+                    if (index === -1) {
+                        this.staleObjects.push(id);
+                    }
+                } else {
+                    if (index !== -1) {
+                        this.staleObjects.splice(index, 1);
+                    }
+                }
+            }
+        },
         loadingUpdated(loading) {
             this.loading = loading;
         },
         destroy() {
+            if (this.stalenessSubscription) {
+                Object.values(this.stalenessSubscription).forEach(stalenessSubscription => {
+                    stalenessSubscription.unsubscribe();
+                    stalenessSubscription.stalenessUtils.destroy();
+                });
+            }
+
+            if (this.compositionCollection) {
+                this.compositionCollection.off('add', this.addItem);
+                this.compositionCollection.off('remove', this.removeItem);
+            }
+
             this.stopListening();
         },
         exportJPG() {

src/plugins/plot/legend/PlotLegendItemCollapsed.vue

@@ -23,6 +23,7 @@
 <div
     class="plot-legend-item"
     :class="{
+        'is-stale': isStale,
         'is-status--missing': isMissing
     }"
     @mouseover="toggleHover(true)"
@@ -55,8 +56,10 @@
 
 import {getLimitClass} from "@/plugins/plot/chart/limitUtil";
 import eventHelpers from "../lib/eventHelpers";
+import stalenessMixin from '@/ui/mixins/staleness-mixin';
 
 export default {
+    mixins: [stalenessMixin],
     inject: ['openmct', 'domainObject'],
     props: {
         valueToShowWhenCollapsed: {
@@ -112,6 +115,7 @@ export default {
         this.listenTo(this.seriesObject, 'change:name', () => {
             this.updateName();
         }, this);
+        this.subscribeToStaleness(this.seriesObject.domainObject);
         this.initialize();
     },
     beforeDestroy() {
@@ -120,6 +124,7 @@ export default {
     methods: {
         initialize(highlightedObject) {
             const seriesObject = highlightedObject ? highlightedObject.series : this.seriesObject;
+
             this.isMissing = seriesObject.domainObject.status === 'missing';
             this.colorAsHexString = seriesObject.get('color').asHexString();
             this.nameWithUnit = seriesObject.nameWithUnit();

src/plugins/plot/legend/PlotLegendItemExpanded.vue

@@ -23,6 +23,7 @@
 <tr
     class="plot-legend-item"
     :class="{
+        'is-stale': isStale,
         'is-status--missing': isMissing
     }"
     @mouseover="toggleHover(true)"
@@ -81,8 +82,10 @@
 <script>
 import {getLimitClass} from "@/plugins/plot/chart/limitUtil";
 import eventHelpers from "@/plugins/plot/lib/eventHelpers";
+import stalenessMixin from '@/ui/mixins/staleness-mixin';
 
 export default {
+    mixins: [stalenessMixin],
     inject: ['openmct', 'domainObject'],
     props: {
         seriesObject: {
@@ -149,6 +152,7 @@ export default {
         this.listenTo(this.seriesObject, 'change:name', () => {
             this.updateName();
         }, this);
+        this.subscribeToStaleness(this.seriesObject.domainObject);
         this.initialize();
     },
     beforeDestroy() {

src/plugins/plot/stackedPlot/StackedPlotItem.vue

@@ -27,12 +27,13 @@
 import MctPlot from '../MctPlot.vue';
 import Vue from "vue";
 import conditionalStylesMixin from "./mixins/objectStyles-mixin";
+import stalenessMixin from '@/ui/mixins/staleness-mixin';
 import configStore from "@/plugins/plot/configuration/ConfigStore";
 import PlotConfigurationModel from "@/plugins/plot/configuration/PlotConfigurationModel";
 import ProgressBar from "../../../ui/components/ProgressBar.vue";
 
 export default {
-    mixins: [conditionalStylesMixin],
+    mixins: [conditionalStylesMixin, stalenessMixin],
     inject: ['openmct', 'domainObject', 'path'],
     props: {
         childObject: {
@@ -114,6 +115,10 @@ export default {
             }
         },
         updateView() {
+            this.isStale = false;
+
+            this.triggerUnsubscribeFromStaleness();
+
             if (this.component) {
                 this.component.$destroy();
                 this.component = undefined;
@@ -139,6 +144,10 @@ export default {
             let viewContainer = document.createElement('div');
             this.$el.append(viewContainer);
 
+            this.subscribeToStaleness(object, (isStale) => {
+                this.updateComponentProp('isStale', isStale);
+            });
+
             this.component = new Vue({
                 el: viewContainer,
                 components: {
@@ -169,7 +178,7 @@ export default {
                         this.loading = loaded;
                     }
                 },
-                template: '<div v-if="!isMissing" ref="plotWrapper" class="l-view-section u-style-receiver js-style-receiver" :class="{\'s-status-timeconductor-unsynced\': status && status === \'timeconductor-unsynced\'}"><progress-bar v-show="loading !== false" class="c-telemetry-table__progress-bar" :model="{progressPerc: undefined}" /><mct-plot :init-grid-lines="gridLines" :init-cursor-guide="cursorGuide" :plot-tick-width="plotTickWidth" :limit-line-labels="limitLineLabels" :color-palette="colorPalette" :options="options" @plotTickWidth="onTickWidthChange" @lockHighlightPoint="onLockHighlightPointUpdated" @highlights="onHighlightsUpdated" @configLoaded="onConfigLoaded" @cursorGuide="onCursorGuideChange" @gridLines="onGridLinesChange" @statusUpdated="setStatus" @loadingUpdated="loadingUpdated"/></div>'
+                template: '<div v-if="!isMissing" ref="plotWrapper" class="l-view-section u-style-receiver js-style-receiver" :class="{\'s-status-timeconductor-unsynced\': status && status === \'timeconductor-unsynced\', \'is-stale\': isStale}"><progress-bar v-show="loading !== false" class="c-telemetry-table__progress-bar" :model="{progressPerc: undefined}" /><mct-plot :init-grid-lines="gridLines" :init-cursor-guide="cursorGuide" :plot-tick-width="plotTickWidth" :limit-line-labels="limitLineLabels" :color-palette="colorPalette" :options="options" @plotTickWidth="onTickWidthChange" @lockHighlightPoint="onLockHighlightPointUpdated" @highlights="onHighlightsUpdated" @configLoaded="onConfigLoaded" @cursorGuide="onCursorGuideChange" @gridLines="onGridLinesChange" @statusUpdated="setStatus" @loadingUpdated="loadingUpdated"/></div>'
             });
 
             this.setSelection();
@@ -215,7 +224,8 @@ export default {
                 plotTickWidth: this.plotTickWidth,
                 options: this.options,
                 status: this.status,
-                colorPalette: this.colorPalette
+                colorPalette: this.colorPalette,
+                isStale: this.isStale
             };
         },
         getPlotObject() {

src/plugins/plugins.js

@@ -155,7 +155,7 @@ define([
     plugins.example.ExampleFaultSource = ExampleFaultSource.default;
     plugins.example.EventGeneratorPlugin = EventGeneratorPlugin.default;
     plugins.example.ExampleTags = ExampleTags.default;
-    plugins.example.Generator = () => GeneratorPlugin;
+    plugins.example.Generator = () => GeneratorPlugin.default;
 
     plugins.UTCTimeSystem = UTCTimeSystem.default;
     plugins.LocalTimeSystem = LocalTimeSystem;

src/plugins/telemetryTable/TelemetryTable.js

@@ -28,7 +28,8 @@ define([
     './TelemetryTableNameColumn',
     './TelemetryTableColumn',
     './TelemetryTableUnitColumn',
-    './TelemetryTableConfiguration'
+    './TelemetryTableConfiguration',
+    '@/utils/staleness'
 ], function (
     EventEmitter,
     _,
@@ -37,7 +38,8 @@ define([
     TelemetryTableNameColumn,
     TelemetryTableColumn,
     TelemetryTableUnitColumn,
-    TelemetryTableConfiguration
+    TelemetryTableConfiguration,
+    StalenessUtils
 ) {
     class TelemetryTable extends EventEmitter {
         constructor(domainObject, openmct) {
@@ -56,6 +58,7 @@ define([
             this.telemetryCollections = {};
             this.delayedActions = [];
             this.outstandingRequests = 0;
+            this.stalenessSubscription = {};
 
             this.addTelemetryObject = this.addTelemetryObject.bind(this);
             this.removeTelemetryObject = this.removeTelemetryObject.bind(this);
@@ -155,6 +158,19 @@ define([
             this.telemetryCollections[keyString].on('clear', this.clearData);
             this.telemetryCollections[keyString].load();
 
+            this.stalenessSubscription[keyString] = {};
+            this.stalenessSubscription[keyString].stalenessUtils = new StalenessUtils.default(this.openmct, telemetryObject);
+            this.openmct.telemetry.isStale(telemetryObject).then(stalenessResponse => {
+                if (stalenessResponse !== undefined) {
+                    this.handleStaleness(keyString, stalenessResponse);
+                }
+            });
+            const stalenessSubscription = this.openmct.telemetry.subscribeToStaleness(telemetryObject, (stalenessResponse) => {
+                this.handleStaleness(keyString, stalenessResponse);
+            });
+
+            this.stalenessSubscription[keyString].unsubscribe = stalenessSubscription;
+
             this.telemetryObjects[keyString] = {
                 telemetryObject,
                 keyString,
@@ -166,6 +182,15 @@ define([
             this.emit('object-added', telemetryObject);
         }
 
+        handleStaleness(keyString, stalenessResponse, skipCheck = false) {
+            if (skipCheck || this.stalenessSubscription[keyString].stalenessUtils.shouldUpdateStaleness(stalenessResponse, keyString)) {
+                this.emit('telemetry-staleness', {
+                    keyString,
+                    isStale: stalenessResponse.isStale
+                });
+            }
+        }
+
         getTelemetryProcessor(keyString, columnMap, limitEvaluator) {
             return (telemetry) => {
                 //Check that telemetry object has not been removed since telemetry was requested.
@@ -255,6 +280,7 @@ define([
 
         removeTelemetryObject(objectIdentifier) {
             const keyString = this.openmct.objects.makeKeyString(objectIdentifier);
+            const SKIP_CHECK = true;
 
             this.configuration.removeColumnsForObject(objectIdentifier, true);
             this.tableRows.removeRowsByObject(keyString);
@@ -263,6 +289,10 @@ define([
             delete this.telemetryObjects[keyString];
 
             this.emit('object-removed', objectIdentifier);
+
+            this.stalenessSubscription[keyString].unsubscribe();
+            this.stalenessSubscription[keyString].stalenessUtils.destroy();
+            this.handleStaleness(keyString, { isStale: false }, SKIP_CHECK);
         }
 
         clearData() {
@@ -368,6 +398,11 @@ define([
                 this.filterObserver();
             }
 
+            Object.values(this.stalenessSubscription).forEach(stalenessSubscription => {
+                stalenessSubscription.unsubscribe();
+                stalenessSubscription.stalenessUtils.destroy();
+            });
+
             if (this.tableComposition !== undefined) {
                 this.tableComposition.off('add', this.addTelemetryObject);
                 this.tableComposition.off('remove', this.removeTelemetryObject);

src/plugins/telemetryTable/components/table.vue

@@ -22,7 +22,7 @@
 <template>
 <div
     class="c-table-wrapper"
-    :class="{ 'is-paused': paused }"
+    :class="tableClasses"
 >
     <div
         v-if="enableLegacyToolbar"
@@ -381,7 +381,8 @@ export default {
             enableRegexSearch: {},
             hideHeaders: configuration.hideHeaders,
             totalNumberOfRows: 0,
-            rowContext: {}
+            rowContext: {},
+            staleObjects: []
         };
     },
     computed: {
@@ -416,6 +417,19 @@ export default {
             }
 
             return style;
+        },
+        tableClasses() {
+            let classes = [];
+
+            if (this.paused) {
+                classes.push('is-paused');
+            }
+
+            if (this.staleObjects.length !== 0) {
+                classes.push('is-stale');
+            }
+
+            return classes;
         }
     },
     watch: {
@@ -488,6 +502,7 @@ export default {
         this.table.on('refresh', this.clearRowsAndRerender);
         this.table.on('historical-rows-processed', this.checkForMarkedRows);
         this.table.on('outstanding-requests', this.outstandingRequests);
+        this.table.on('telemetry-staleness', this.handleStaleness);
 
         this.table.tableRows.on('add', this.rowsAdded);
         this.table.tableRows.on('remove', this.rowsRemoved);
@@ -516,6 +531,7 @@ export default {
         this.table.off('historical-rows-processed', this.checkForMarkedRows);
         this.table.off('refresh', this.clearRowsAndRerender);
         this.table.off('outstanding-requests', this.outstandingRequests);
+        this.table.off('telemetry-staleness', this.handleStaleness);
 
         this.table.tableRows.off('add', this.rowsAdded);
         this.table.tableRows.off('remove', this.rowsRemoved);
@@ -726,6 +742,18 @@ export default {
         outstandingRequests(loading) {
             this.loading = loading;
         },
+        handleStaleness({ keyString, isStale }) {
+            const index = this.staleObjects.indexOf(keyString);
+            if (isStale) {
+                if (index === -1) {
+                    this.staleObjects.push(keyString);
+                }
+            } else {
+                if (index !== -1) {
+                    this.staleObjects.splice(index, 1);
+                }
+            }
+        },
         calculateTableSize() {
             this.$nextTick().then(this.calculateColumnWidths);
         },

src/styles/_constants-espresso.scss

@@ -305,8 +305,8 @@ $colorIndicatorMenuFg: $colorHeadFg;
 $colorIndicatorMenuFgHov: pullForward($colorHeadFg, 10%);
 
 // Staleness
-$colorTelemFresh: pullForward($colorBodyFg, 20%);
+$colorTelemStale: cyan;
-$colorTelemStale: pushBack($colorBodyFg, 20%);
+$colorTelemStaleFg: #002A2A;
 $styleTelemStale: italic;
 
 // Limits

src/styles/_constants-maelstrom.scss

@@ -309,8 +309,8 @@ $colorIndicatorMenuFg: $colorHeadFg;
 $colorIndicatorMenuFgHov: pullForward($colorHeadFg, 10%);
 
 // Staleness
-$colorTelemFresh: pullForward($colorBodyFg, 20%);
+$colorTelemStale: cyan;
-$colorTelemStale: pushBack($colorBodyFg, 20%);
+$colorTelemStaleFg: #002A2A;
 $styleTelemStale: italic;
 
 // Limits

src/styles/_constants-snow.scss

@@ -305,8 +305,8 @@ $colorIndicatorMenuFg: $colorHeadFg;
 $colorIndicatorMenuFgHov: pullForward($colorHeadFg, 10%);
 
 // Staleness
-$colorTelemFresh: pullForward($colorBodyFg, 20%);
+$colorTelemStale: #00c9c9;
-$colorTelemStale: pushBack($colorBodyFg, 20%);
+$colorTelemStaleFg: #002A2A;
 $styleTelemStale: italic;
 
 // Limits

src/styles/_constants.scss

@@ -164,6 +164,7 @@ $glyph-icon-status-poll-caution: '\e933';
 $glyph-icon-status-poll-circle-slash: '\e934';
 $glyph-icon-status-poll-question-mark: '\e935';
 $glyph-icon-status-poll-edit: '\e936';
+$glyph-icon-stale: '\e937';
 $glyph-icon-arrows-right-left: '\ea00';
 $glyph-icon-arrows-up-down: '\ea01';
 $glyph-icon-bullet: '\ea02';

src/styles/_glyphs.scss

@@ -95,6 +95,7 @@
 .icon-status-poll-circle-slash {  @include glyphBefore($glyph-icon-status-poll-circle-slash); }
 .icon-status-poll-question-mark {  @include glyphBefore($glyph-icon-status-poll-question-mark); }
 .icon-status-poll-edit {  @include glyphBefore($glyph-icon-status-poll-edit); }
+.icon-stale {  @include glyphBefore($glyph-icon-stale); }
 .icon-arrows-right-left {  @include glyphBefore($glyph-icon-arrows-right-left); }
 .icon-arrows-up-down {  @include glyphBefore($glyph-icon-arrows-up-down); }
 .icon-bullet {  @include glyphBefore($glyph-icon-bullet); }

src/styles/_legacy-plots.scss

@@ -81,6 +81,10 @@ mct-plot {
         overflow-x: hidden;
     }
 
+    &.is-stale {
+        @include isStaleHolder();
+    }
+
     .c-plot--stacked-container {
         border: 1px solid transparent;
         display: flex;
@@ -89,6 +93,10 @@ mct-plot {
         min-height: $plotMinH;
         overflow: hidden;
 
+        .is-stale {
+            @include isStaleHolder();
+        }
+
         &[s-selected] {
             .is-editing & {
                 border: $editMarqueeBorder;
@@ -596,6 +604,10 @@ mct-plot {
         margin-left: $interiorMarginSm;
     }
 
+    &.is-stale {
+        @include isStaleElement();
+    }
+
     .plot-series-color-swatch {
         @include colorSwatch();
         display: inline-block;
@@ -649,8 +661,10 @@ mct-plot {
         // .plot-legend-item is a span of spans.
 
         .plot-legend-item {
+            border-radius: $smallCr;
             display: flex;
             justify-content: stretch;
+            padding: 1px;
 
             .plot-series-swatch-and-name,
             .plot-series-value {

src/styles/_mixins.scss

@@ -153,6 +153,37 @@
     }
 }
 
+@mixin isStaleGlyph() {
+    content: $glyph-icon-stale;
+    display: block;
+    font-family: symbolsfont;
+    font-style: normal;
+    pointer-events: none;
+}
+
+@mixin isStaleHolder() {
+    // Applied to objects that frame content, like Display Layout frames, plots, etc.
+    border-radius: 3px;
+    border: 2px solid rgba($colorTelemStale, 0.8) !important;
+
+    &:before {
+        @include isStaleGlyph();
+        color: $colorTelemStale;
+        position: absolute;
+        bottom: 5px;
+        left: 3px;
+        width: 12px;
+        z-index: 10;
+    }
+}
+
+@mixin isStaleElement() {
+    // Applied directly to values, like LAD Table cells, alphanumerics, plot legend items
+    background: $colorTelemStale !important;
+    color: $colorTelemStaleFg !important;
+    font-style: italic;
+}
+
 @mixin isLimit() {
     &[class*='is-limit'] {
         &:before {

src/styles/_table.scss

@@ -90,6 +90,10 @@ div.c-table {
         flex: 1 1 auto;
     }
 
+    &.is-stale {
+        @include isStaleHolder();
+    }
+
     .--width-less-than-600 & {
         &:not(.is-paused) {
             .c-table-control-bar {
@@ -179,12 +183,22 @@ div.c-table {
     width: 100%;
     height: 100%;
     padding: $mainViewPad;
+
+    &.is-stale {
+        @include isStaleHolder();
+    }
 }
 
 .c-lad-table {
     th, td {
         width: 33%; // Needed to prevent size jumping as values dynamically update
     }
+
+    td {
+        &.is-stale {
+            @include isStaleElement();
+        }
+    }
 }
 
 /************************************** TABLE AND SUMMARY VIEWS */

src/styles/fonts/Open MCT Symbols 16px.json

@@ -2,7 +2,7 @@
   "metadata": {
     "name": "Open MCT Symbols 16px",
     "lastOpened": 0,
-    "created": 1660771219523
+    "created": 1674103729548
   },
   "iconSets": [
     {
@@ -447,13 +447,21 @@
           "code": 59702,
           "tempChar": ""
         },
+        {
+          "order": 215,
+          "id": 185,
+          "name": "icon-stale",
+          "prevSize": 16,
+          "code": 59703,
+          "tempChar": ""
+        },
         {
           "order": 27,
           "id": 105,
           "name": "icon-arrows-right-left",
           "prevSize": 16,
           "code": 59904,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 26,
@@ -461,7 +469,7 @@
           "name": "icon-arrows-up-down",
           "prevSize": 16,
           "code": 59905,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 68,
@@ -469,7 +477,7 @@
           "name": "icon-bullet",
           "prevSize": 16,
           "code": 59906,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 150,
@@ -477,7 +485,7 @@
           "prevSize": 16,
           "code": 59907,
           "name": "icon-calendar",
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 45,
@@ -485,7 +493,7 @@
           "name": "icon-chain-links",
           "prevSize": 16,
           "code": 59908,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 73,
@@ -493,7 +501,7 @@
           "name": "icon-download",
           "prevSize": 16,
           "code": 59909,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 39,
@@ -501,7 +509,7 @@
           "name": "icon-duplicate",
           "prevSize": 16,
           "code": 59910,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 50,
@@ -509,7 +517,7 @@
           "name": "icon-folder-new",
           "prevSize": 16,
           "code": 59911,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 138,
@@ -517,7 +525,7 @@
           "name": "icon-fullscreen-collapse",
           "prevSize": 16,
           "code": 59912,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 139,
@@ -525,7 +533,7 @@
           "name": "icon-fullscreen-expand",
           "prevSize": 16,
           "code": 59913,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 122,
@@ -533,7 +541,7 @@
           "name": "icon-layers",
           "prevSize": 16,
           "code": 59914,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 151,
@@ -541,7 +549,7 @@
           "name": "icon-line-horz",
           "prevSize": 16,
           "code": 59915,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 100,
@@ -549,7 +557,7 @@
           "name": "icon-magnify",
           "prevSize": 16,
           "code": 59916,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 99,
@@ -557,7 +565,7 @@
           "name": "icon-magnify-in",
           "prevSize": 16,
           "code": 59917,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 101,
@@ -565,7 +573,7 @@
           "name": "icon-magnify-out-v2",
           "prevSize": 16,
           "code": 59918,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 103,
@@ -573,7 +581,7 @@
           "name": "icon-menu",
           "prevSize": 16,
           "code": 59919,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 124,
@@ -581,7 +589,7 @@
           "name": "icon-move",
           "prevSize": 16,
           "code": 59920,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 7,
@@ -589,7 +597,7 @@
           "name": "icon-new-window",
           "prevSize": 16,
           "code": 59921,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 63,
@@ -597,7 +605,7 @@
           "name": "icon-paint-bucket-v2",
           "prevSize": 16,
           "code": 59922,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 15,
@@ -605,7 +613,7 @@
           "name": "icon-pencil",
           "prevSize": 16,
           "code": 59923,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 54,
@@ -613,7 +621,7 @@
           "name": "icon-pencil-edit-in-place",
           "prevSize": 16,
           "code": 59924,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 40,
@@ -621,7 +629,7 @@
           "name": "icon-play",
           "prevSize": 16,
           "code": 59925,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 125,
@@ -629,7 +637,7 @@
           "name": "icon-pause",
           "prevSize": 16,
           "code": 59926,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 119,
@@ -637,7 +645,7 @@
           "name": "icon-plot-resource",
           "prevSize": 16,
           "code": 59927,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 48,
@@ -645,7 +653,7 @@
           "name": "icon-pointer-left",
           "prevSize": 16,
           "code": 59928,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 47,
@@ -653,7 +661,7 @@
           "name": "icon-pointer-right",
           "prevSize": 16,
           "code": 59929,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 85,
@@ -661,7 +669,7 @@
           "name": "icon-refresh",
           "prevSize": 16,
           "code": 59930,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 55,
@@ -669,7 +677,7 @@
           "name": "icon-save",
           "prevSize": 16,
           "code": 59931,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 56,
@@ -677,7 +685,7 @@
           "name": "icon-save-as",
           "prevSize": 16,
           "code": 59932,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 58,
@@ -685,7 +693,7 @@
           "name": "icon-sine",
           "prevSize": 16,
           "code": 59933,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 113,
@@ -693,7 +701,7 @@
           "name": "icon-font",
           "prevSize": 16,
           "code": 59934,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 41,
@@ -701,7 +709,7 @@
           "name": "icon-thumbs-strip",
           "prevSize": 16,
           "code": 59935,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 146,
@@ -709,7 +717,7 @@
           "name": "icon-two-parts-both",
           "prevSize": 16,
           "code": 59936,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 145,
@@ -717,7 +725,7 @@
           "name": "icon-two-parts-one-only",
           "prevSize": 16,
           "code": 59937,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 82,
@@ -725,7 +733,7 @@
           "name": "icon-resync",
           "prevSize": 16,
           "code": 59938,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 86,
@@ -733,7 +741,7 @@
           "name": "icon-reset",
           "prevSize": 16,
           "code": 59939,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 61,
@@ -741,7 +749,7 @@
           "name": "icon-x-in-circle",
           "prevSize": 16,
           "code": 59940,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 84,
@@ -749,7 +757,7 @@
           "name": "icon-brightness",
           "prevSize": 16,
           "code": 59941,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 83,
@@ -757,7 +765,7 @@
           "name": "icon-contrast",
           "prevSize": 16,
           "code": 59942,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 87,
@@ -765,7 +773,7 @@
           "name": "icon-expand",
           "prevSize": 16,
           "code": 59943,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 89,
@@ -773,7 +781,7 @@
           "name": "icon-list-view",
           "prevSize": 16,
           "code": 59944,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 133,
@@ -781,7 +789,7 @@
           "name": "icon-grid-snap-to",
           "prevSize": 16,
           "code": 59945,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 132,
@@ -789,7 +797,7 @@
           "name": "icon-grid-snap-no",
           "prevSize": 16,
           "code": 59946,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 94,
@@ -797,7 +805,7 @@
           "name": "icon-frame-show",
           "prevSize": 16,
           "code": 59947,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 95,
@@ -805,7 +813,7 @@
           "name": "icon-frame-hide",
           "prevSize": 16,
           "code": 59948,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 97,
@@ -813,7 +821,7 @@
           "name": "icon-import",
           "prevSize": 16,
           "code": 59949,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 96,
@@ -821,7 +829,7 @@
           "name": "icon-export",
           "prevSize": 16,
           "code": 59950,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 194,
@@ -829,7 +837,7 @@
           "name": "icon-font-size",
           "prevSize": 16,
           "code": 59951,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 163,
@@ -837,7 +845,7 @@
           "name": "icon-clear-data",
           "prevSize": 16,
           "code": 59952,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 173,
@@ -845,7 +853,7 @@
           "name": "icon-history",
           "prevSize": 16,
           "code": 59953,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 181,
@@ -853,7 +861,7 @@
           "name": "icon-arrow-up-to-parent",
           "prevSize": 16,
           "code": 59954,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 184,
@@ -861,7 +869,7 @@
           "name": "icon-crosshair-in-circle",
           "prevSize": 16,
           "code": 59955,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 185,
@@ -869,7 +877,7 @@
           "name": "icon-target",
           "prevSize": 16,
           "code": 59956,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 187,
@@ -877,7 +885,7 @@
           "name": "icon-items-collapse",
           "prevSize": 16,
           "code": 59957,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 188,
@@ -885,7 +893,7 @@
           "name": "icon-items-expand",
           "prevSize": 16,
           "code": 59958,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 190,
@@ -893,7 +901,7 @@
           "name": "icon-3-dots",
           "prevSize": 16,
           "code": 59959,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 193,
@@ -901,7 +909,7 @@
           "name": "icon-grid-on",
           "prevSize": 16,
           "code": 59960,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 192,
@@ -909,7 +917,7 @@
           "name": "icon-grid-off",
           "prevSize": 16,
           "code": 59961,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 191,
@@ -917,7 +925,7 @@
           "name": "icon-camera",
           "prevSize": 16,
           "code": 59962,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 196,
@@ -925,7 +933,7 @@
           "name": "icon-folders-collapse",
           "prevSize": 16,
           "code": 59963,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 144,
@@ -933,7 +941,7 @@
           "name": "icon-activity",
           "prevSize": 16,
           "code": 60160,
-          "tempChar": ""
+          "tempChar": ""
         },
         {
           "order": 104,
@@ -941,7 +949,7 @@
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+          "tempChar": ""
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@@ -949,7 +957,7 @@
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-          "tempChar": ""
+          "tempChar": ""
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@@ -957,7 +965,7 @@
           "name": "icon-clock",
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           "code": 60163,
-          "tempChar": ""
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@@ -965,7 +973,7 @@
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           "code": 60164,
-          "tempChar": ""
+          "tempChar": ""
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@@ -973,7 +981,7 @@
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           "prevSize": 16,
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-          "tempChar": ""
+          "tempChar": ""
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@@ -981,7 +989,7 @@
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-          "tempChar": ""
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@@ -989,7 +997,7 @@
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           "code": 60167,
-          "tempChar": ""
+          "tempChar": ""
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@@ -997,7 +1005,7 @@
           "name": "icon-dictionary",
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           "code": 60168,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1005,7 +1013,7 @@
           "name": "icon-folder",
           "prevSize": 16,
           "code": 60169,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1013,7 +1021,7 @@
           "name": "icon-image",
           "prevSize": 16,
           "code": 60170,
-          "tempChar": ""
+          "tempChar": ""
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           "order": 4,
@@ -1021,7 +1029,7 @@
           "name": "icon-layout",
           "prevSize": 16,
           "code": 60171,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1029,7 +1037,7 @@
           "name": "icon-object",
           "prevSize": 16,
           "code": 60172,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1037,7 +1045,7 @@
           "name": "icon-object-unknown",
           "prevSize": 16,
           "code": 60173,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1045,7 +1053,7 @@
           "name": "icon-packet",
           "prevSize": 16,
           "code": 60174,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1053,7 +1061,7 @@
           "name": "icon-page",
           "prevSize": 16,
           "code": 60175,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1061,7 +1069,7 @@
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           "prevSize": 16,
           "code": 60176,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1069,7 +1077,7 @@
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           "code": 60177,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1077,7 +1085,7 @@
           "name": "icon-session",
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           "code": 60178,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1085,7 +1093,7 @@
           "name": "icon-tabular",
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           "code": 60179,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1093,7 +1101,7 @@
           "name": "icon-tabular-lad",
           "prevSize": 16,
           "code": 60180,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1101,7 +1109,7 @@
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           "prevSize": 16,
           "code": 60181,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1109,7 +1117,7 @@
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           "prevSize": 16,
           "code": 60182,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1117,7 +1125,7 @@
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           "prevSize": 16,
           "code": 60183,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1125,7 +1133,7 @@
           "name": "icon-telemetry",
           "prevSize": 16,
           "code": 60184,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1133,7 +1141,7 @@
           "name": "icon-timeline",
           "prevSize": 16,
           "code": 60185,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1141,7 +1149,7 @@
           "name": "icon-timer",
           "prevSize": 16,
           "code": 60186,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1149,7 +1157,7 @@
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           "prevSize": 16,
           "code": 60187,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1157,7 +1165,7 @@
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           "prevSize": 16,
           "code": 60188,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1165,7 +1173,7 @@
           "name": "icon-summary-widget",
           "prevSize": 16,
           "code": 60189,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1173,7 +1181,7 @@
           "name": "icon-notebook",
           "prevSize": 16,
           "code": 60190,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1181,7 +1189,7 @@
           "name": "icon-tabs-view",
           "prevSize": 16,
           "code": 60191,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1189,7 +1197,7 @@
           "name": "icon-flexible-layout",
           "prevSize": 16,
           "code": 60192,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1197,7 +1205,7 @@
           "name": "icon-generator-sine",
           "prevSize": 16,
           "code": 60193,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1205,7 +1213,7 @@
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           "prevSize": 16,
           "code": 60194,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1213,7 +1221,7 @@
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           "prevSize": 16,
           "code": 60195,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1221,7 +1229,7 @@
           "name": "icon-spectra",
           "prevSize": 16,
           "code": 60196,
-          "tempChar": ""
+          "tempChar": ""
         },
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@@ -1229,7 +1237,7 @@
           "name": "icon-telemetry-spectra",
           "prevSize": 16,
           "code": 60197,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1237,7 +1245,7 @@
           "name": "icon-pushbutton",
           "prevSize": 16,
           "code": 60198,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1245,7 +1253,7 @@
           "name": "icon-conditional",
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           "code": 60199,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1253,7 +1261,7 @@
           "name": "icon-condition-widget",
           "prevSize": 16,
           "code": 60200,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1261,7 +1269,7 @@
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           "prevSize": 16,
           "code": 60201,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1269,7 +1277,7 @@
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           "prevSize": 16,
           "code": 60202,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1277,7 +1285,7 @@
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           "prevSize": 16,
           "code": 60203,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1285,7 +1293,7 @@
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           "prevSize": 16,
           "code": 60204,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1293,7 +1301,7 @@
           "name": "icon-map",
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           "code": 60205,
-          "tempChar": ""
+          "tempChar": ""
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           "order": 203,
@@ -1301,7 +1309,7 @@
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           "prevSize": 16,
           "code": 60206,
-          "tempChar": ""
+          "tempChar": ""
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@@ -1309,14 +1317,6 @@
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-          "tempChar": ""
-        },
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-          "id": 184,
-          "name": "icon-notebook-restricted",
-          "prevSize": 16,
-          "code": 60209,
           "tempChar": ""
         },
         {
@@ -1326,6 +1326,14 @@
           "prevSize": 16,
           "code": 60208,
           "tempChar": ""
+        },
+        {
+          "order": 214,
+          "id": 184,
+          "name": "icon-notebook-restricted",
+          "prevSize": 16,
+          "code": 60209,
+          "tempChar": ""
         }
       ],
       "id": 0,
@@ -2327,6 +2335,26 @@
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+<glyph unicode="&#xe937;" glyph-name="icon-stale" d="M832 896h-640c-105.6 0-192-86.4-192-192v-640c0-105.6 86.4-192 192-192h640c105.6 0 192 86.4 192 192v640c0 105.6-86.4 192-192 192zM681.38 530.86c0.68 20.46-2.22 37.7-8.7 51.68-6.5 13.98-15.7 25.4-27.64 34.28-11.94 8.86-26.1 15.18-42.48 18.94-16.38 3.74-33.78 5.62-52.2 5.62-15.020 0-30.2-1.54-45.54-4.6s-29.16-8.18-41.44-15.36-22.18-16.56-29.68-28.14c-7.52-11.62-11.26-25.94-11.26-42.98s6.66-32.6 19.96-44.52c13.3-11.94 29.34-21.84 48.1-29.68 18.76-7.86 38.020-14 57.82-18.42 19.78-4.44 35.82-8.020 48.1-10.74 28.66-7.52 54.92-16.22 78.8-26.1 23.88-9.9 44.52-22.68 61.92-38.38s30.86-34.8 40.42-57.32c9.54-22.52 14.32-50.16 14.32-82.9 0-43.68-9.040-80.86-27.12-111.56s-41.28-55.62-69.6-74.7c-28.32-19.1-60.22-32.92-95.7-41.44s-70.62-12.8-105.42-12.8c-102.34 0-178.6 20.8-228.74 62.44-50.16 41.6-75.22 107.1-75.22 196.5h152.5c-1.38-25.94 1.7-47.58 9.22-64.98 7.5-17.4 18.42-31.22 32.74-41.44 14.32-10.24 31.38-17.58 51.18-22 19.78-4.44 41.28-6.66 64.48-6.66 16.38 0 32.74 2.040 49.12 6.14s31.22 10.24 44.52 18.42c13.3 8.18 24.22 18.76 32.76 31.72 8.52 12.94 12.8 28.66 12.8 47.080s-5.46 32.24-16.38 43.5c-10.92 11.26-25.080 20.98-42.48 29.16s-37.2 15.36-59.36 21.5c-22.18 6.14-44.52 12.62-67.040 19.44-23.2 6.82-45.72 15-67.54 24.56-21.84 9.54-41.44 21.82-58.84 36.84-17.4 15-31.38 33.42-41.96 55.26-10.58 21.82-15.86 48.44-15.86 79.82 0 40.94 8.52 75.74 25.58 104.4 17.040 28.66 39.22 52.020 66.52 70.1 27.28 18.080 58.16 31.38 92.62 39.92 34.44 8.52 69.42 12.8 104.9 12.8 37.52 0 72.82-4.26 105.92-12.8 33.080-8.54 62.080-22.36 87-41.44 24.9-19.1 44.68-43.5 59.36-73.18 14.66-29.68 22-65.68 22-107.98h-152.5z" />
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 <glyph unicode="&#xea02;" glyph-name="icon-bullet" d="M832 144c0-44-36-80-80-80h-480c-44 0-80 36-80 80v480c0 44 36 80 80 80h480c44 0 80-36 80-80v-480z" />

src/ui/components/ObjectView.vue

@@ -14,7 +14,7 @@
     <div
         ref="objectViewWrapper"
         class="c-object-view"
-        :class="objectTypeClass"
+        :class="viewClasses"
     ></div>
 </div>
 </template>
@@ -24,6 +24,7 @@ import _ from "lodash";
 import StyleRuleManager from "@/plugins/condition/StyleRuleManager";
 import {STYLE_CONSTANTS} from "@/plugins/condition/utils/constants";
 import IndependentTimeConductor from '@/plugins/timeConductor/independent/IndependentTimeConductor.vue';
+import stalenessMixin from '@/ui/mixins/staleness-mixin';
 
 const SupportedViewTypes = [
     'plot-stacked',
@@ -36,6 +37,7 @@ export default {
     components: {
         IndependentTimeConductor
     },
+    mixins: [stalenessMixin],
     inject: ["openmct"],
     props: {
         showEditView: Boolean,
@@ -85,8 +87,14 @@ export default {
 
             return this.domainObject && SupportedViewTypes.includes(viewKey);
         },
-        objectTypeClass() {
+        viewClasses() {
-            return this.domainObject && ('is-object-type-' + this.domainObject.type);
+            let classes;
+
+            if (this.domainObject) {
+                classes = `is-object-type-${this.domainObject.type} ${this.isStale ? 'is-stale' : ''}`;
+            }
+
+            return classes;
         }
     },
     destroyed() {
@@ -128,6 +136,7 @@ export default {
         if (this.domainObject) {
             //This is to apply styles to subobjects in a layout
             this.initObjectStyles();
+            this.triggerStalenessSubscribe(this.domainObject);
         }
     },
     methods: {
@@ -161,6 +170,9 @@ export default {
                 this.composition._destroy();
             }
 
+            this.isStale = false;
+            this.triggerUnsubscribeFromStaleness();
+
             this.openmct.objectViews.off('clearData', this.clearData);
         },
         getStyleReceiver() {
@@ -192,6 +204,11 @@ export default {
             this.clear();
             this.updateView(true);
         },
+        triggerStalenessSubscribe(object) {
+            if (this.openmct.telemetry.isTelemetryObject(object)) {
+                this.subscribeToStaleness(object);
+            }
+        },
         updateStyle(styleObj) {
             let elemToStyle = this.getStyleReceiver();
 
@@ -306,6 +323,7 @@ export default {
 
             this.updateView(immediatelySelect);
 
+            this.triggerStalenessSubscribe(this.domainObject);
             this.initObjectStyles();
         },
         initObjectStyles() {

src/ui/layout/layout.scss

@@ -320,6 +320,10 @@
     display: block;
     height: 100%;
     overflow: auto;
+
+    &.is-stale {
+        @include isStaleHolder();
+    }
 }
 
 .is-editing {

src/ui/mixins/staleness-mixin.js

@@ -0,0 +1,68 @@
+/*****************************************************************************
+ * Open MCT, Copyright (c) 2014-2022, United States Government
+ * as represented by the Administrator of the National Aeronautics and Space
+ * Administration. All rights reserved.
+ *
+ * Open MCT is licensed under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * Open MCT includes source code licensed under additional open source
+ * licenses. See the Open Source Licenses file (LICENSES.md) included with
+ * this source code distribution or the Licensing information page available
+ * at runtime from the About dialog for additional information.
+ *****************************************************************************/
+
+import StalenessUtils from '@/utils/staleness';
+
+export default {
+    data() {
+        return {
+            isStale: false
+        };
+    },
+    beforeDestroy() {
+        this.triggerUnsubscribeFromStaleness();
+    },
+    methods: {
+        subscribeToStaleness(domainObject, callback) {
+            if (!this.stalenessUtils) {
+                this.stalenessUtils = new StalenessUtils(this.openmct, domainObject);
+            }
+
+            this.requestStaleness(domainObject);
+            this.unsubscribeFromStaleness = this.openmct.telemetry.subscribeToStaleness(domainObject, (stalenessResponse) => {
+                this.handleStalenessResponse(stalenessResponse, callback);
+            });
+        },
+        async requestStaleness(domainObject) {
+            const stalenessResponse = await this.openmct.telemetry.isStale(domainObject);
+            if (stalenessResponse !== undefined) {
+                this.handleStalenessResponse(stalenessResponse);
+            }
+        },
+        handleStalenessResponse(stalenessResponse, callback) {
+            if (this.stalenessUtils.shouldUpdateStaleness(stalenessResponse)) {
+                if (typeof callback === 'function') {
+                    callback(stalenessResponse.isStale);
+                } else {
+                    this.isStale = stalenessResponse.isStale;
+                }
+            }
+        },
+        triggerUnsubscribeFromStaleness() {
+            if (this.unsubscribeFromStaleness) {
+                this.unsubscribeFromStaleness();
+                delete this.unsubscribeFromStaleness;
+                this.stalenessUtils.destroy();
+            }
+        }
+    }
+};

src/utils/staleness.js

@@ -0,0 +1,76 @@
+/*****************************************************************************
+ * Open MCT, Copyright (c) 2014-2022, United States Government
+ * as represented by the Administrator of the National Aeronautics and Space
+ * Administration. All rights reserved.
+ *
+ * Open MCT is licensed under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * Open MCT includes source code licensed under additional open source
+ * licenses. See the Open Source Licenses file (LICENSES.md) included with
+ * this source code distribution or the Licensing information page available
+ * at runtime from the About dialog for additional information.
+ *****************************************************************************/
+
+export default class StalenessUtils {
+    constructor(openmct, domainObject) {
+        this.openmct = openmct;
+        this.domainObject = domainObject;
+        this.metadata = this.openmct.telemetry.getMetadata(domainObject);
+        this.lastStalenessResponseTime = 0;
+
+        this.setTimeSystem(this.openmct.time.timeSystem());
+        this.watchTimeSystem();
+    }
+
+    shouldUpdateStaleness(stalenessResponse, id) {
+        const stalenessResponseTime = this.parseTime(stalenessResponse);
+
+        if (stalenessResponseTime > this.lastStalenessResponseTime) {
+            this.lastStalenessResponseTime = stalenessResponseTime;
+
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    watchTimeSystem() {
+        this.openmct.time.on('timeSystem', this.setTimeSystem, this);
+    }
+
+    unwatchTimeSystem() {
+        this.openmct.time.off('timeSystem', this.setTimeSystem, this);
+    }
+
+    setTimeSystem(timeSystem) {
+        let metadataValue = { format: timeSystem.key };
+
+        if (this.metadata) {
+            metadataValue = this.metadata.value(timeSystem.key) ?? metadataValue;
+        }
+
+        const valueFormatter = this.openmct.telemetry.getValueFormatter(metadataValue);
+
+        this.parseTime = (stalenessResponse) => {
+            const stalenessDatum = {
+                ...stalenessResponse,
+                source: stalenessResponse[timeSystem.key]
+            };
+
+            return valueFormatter.parse(stalenessDatum);
+        };
+    }
+
+    destroy() {
+        this.unwatchTimeSystem();
+    }
+}