360 polling

src/hooks/useInterval.ts

@@ -0,0 +1,35 @@
+import { useEffect, useRef } from 'react';
+
+type Callback = () => void;
+
+/**
+ * useInterval custom hook - used similar to useEffect, but for intervals (auto cleanup).
+ * @author David Linhardt
+ *
+ * @param {Callback} callback - callback function
+ * @param {(number | null)} delay - delay in milliseconds
+ */
+function useInterval(callback: Callback, delay: number | null): void {
+    const savedCallback = useRef<Callback | null>(null);
+
+    // Remember the latest callback if it changes.
+    useEffect(() => {
+        savedCallback.current = callback;
+    }, [callback]);
+
+    // Set up the interval.
+    useEffect(() => {
+        function tick() {
+            if (savedCallback.current) {
+                savedCallback.current();
+            }
+        }
+
+        if (delay !== null) {
+            const id = setInterval(tick, delay);
+            return () => clearInterval(id); // cleanup
+        }
+    }, [delay]);
+}
+
+export default useInterval;

src/locales/de/admin.json

@@ -55,6 +55,5 @@
     "setReviewedNotFound": "Die Abgabe mit der E-Mail Adresse {{email}} wurde nicht gefunden.",
     "setReviewedUnprocessableEntity": "Die E-Mail Adresse {{email}} ist nicht gültig.",
     "setReviewedError": "Ein Fehler ist beim aktiv setzen der Abgabe mit der E-Mail Adresse {{email}} aufgetreten. Bitte versuche es später erneut.",
-    "errorFetchingChallenges": "Ein Fehler ist beim Abrufen der Challenges aufgetreten. Bitte versuche es später erneut.",
-    "sseError": "Ein Fehler ist beim Verbinden zum Server aufgetreten ({{event}}). Bitte versuche es später erneut."
+    "errorFetchingChallenges": "Ein Fehler ist beim Abrufen der Challenges aufgetreten. Bitte versuche es später erneut."
 }

src/locales/en/admin.json

@@ -55,6 +55,5 @@
     "setReviewedNotFound": "The submission from email {{email}} could not be found.",
     "setReviewedUnprocessableEntity": "The supplied email address {{email}} is not valid.",
     "setReviewedError": "An error occurred while trying to set the submission from email {{email}} to reviewed. Please try again later.",
-    "errorFetchingChallenges": "An error occurred while trying to fetch the challenges. Please try again later.",
-    "sseError": "An error occurred while trying to establish a connection to the server ({{event}}). Please try again later."
+    "errorFetchingChallenges": "An error occurred while trying to fetch the challenges. Please try again later."
 }

src/pages/Admin/components/Submissions/Submissions.tsx

@@ -13,8 +13,8 @@ import { ToastType } from '../../../../interfaces/ToastType';
 import moment from 'moment';
 import { useAGGridLocaleContext } from '../../../../components/Context/AGGridLocaleContext/useAGGridLocaleContext';
 import { StatusCodes } from 'http-status-codes';
+import useInterval from '../../../../hooks/useInterval';
 
-const baseURL = import.meta.env.VITE_API_URL;
 /**
  * Submissions component used in the admin submissions page.
  * @author Timo Hauser
@@ -39,6 +39,7 @@ export default function Submissions() {
      */
     const { gridLocale } = useAGGridLocaleContext();
 
+    // Refs
     /**
      * AG Grid Reference
      * @author Timo Hauser
@@ -47,6 +48,15 @@ export default function Submissions() {
      */
     const gridRef: LegacyRef<AgGridReact> = useRef<AgGridReact>(null);
 
+    // States
+    /**
+     * Row Data State
+     * @author Timo Hauser
+     *
+     * @type {UserSubmissionTableElement[]}
+     */
+    const [rowData, setRowData] = useState<UserSubmissionTableElement[]>([]);
+
     /**
      * AG Grid Options
      * @author Timo Hauser
@@ -65,60 +75,21 @@ export default function Submissions() {
     };
 
     /**
-     * Row Data State
+     * get the submission status from the backend on page load
      * @author Timo Hauser
-     *
-     * @type {UserSubmissionTableElement[]}
      */
-    const [rowData, setRowData] = useState<UserSubmissionTableElement[]>([]);
-
     useEffect(() => {
-        /**
-         * connect SSE to the backend to get the submission status changes in real time and update the table accordingly
-         * @author Timo Hauser
-         * @author David Linhardt
-         *
-         * @async
-         * @returns {void}
-         */
-        const connect = async () => {
-            try {
-                const res = await submission.heartbeat();
-                if (!res.ok) {
-                    const data = await res.json();
-                    toast.showToast(
-                        ToastType.ERROR,
-                        toast.httpError(res.status, data.error)
-                    );
-                } else {
-                    const sse = new EventSource(
-                        `${baseURL}/v1/admin/submission/status/subscribe`,
-                        { withCredentials: true }
-                    );
-                    sse.addEventListener(
-                        'submission-status-changed',
-                        (event) => {
-                            if (event.data) {
-                                loadSubmissionData();
-                            } else {
-                                console.log('no data');
-                            }
-                        }
-                    );
-                    sse.onerror = () => {
-                        connect();
-                    };
-                }
-            } catch (e: unknown) {
-                toast.showToast(ToastType.ERROR, t('connectionError', { ns: 'main' }));
-            }
-        };
-        connect();
+        loadSubmissionData();
+        // eslint-disable-next-line react-hooks/exhaustive-deps
+    }, []);
 
-        return () => {
-            // clean up
-        };
-    });
+    /**
+     * get the submission status from the backend (polling every 4 seconds) using useInterval hook
+     * @author David Linhardt
+     */
+    useInterval(async () => {
+            loadSubmissionData();
+    }, 4000);
 
     /**
      * set the state of a submission to reviewed in the backend and update the table afterwards
@@ -220,10 +191,6 @@ export default function Submissions() {
         };
     }
 
-    useEffect(() => {
-        loadSubmissionData();
-        // eslint-disable-next-line react-hooks/exhaustive-deps
-    }, []);
     /**
      * JSON Submission Item Interface for the backend response data.
      * @author Timo Hauser

src/services/submission.ts

@@ -86,29 +86,6 @@ const list = async () => {
     return res;
 };
 
-/**
- * List service : update point for frontend, sends a heartbeat every 15 second
- * http://localhost:8080/swagger-ui/index.html#/admin-controller/subscribeToSubmissionStatus
- * @author Timo Hauser
- *
- * @async
- * @returns {Promise<Response>} HTTP response
- * @throws {any} connection error
- */
-const heartbeat = async () => {
-    const url = `${baseURL}/v1/admin/submission/status/subscribe`;
-
-    const res = await fetch(url, {
-        method: 'GET',
-        credentials: 'include',
-        headers: {
-            'Content-Type': 'application/json',
-        },
-    });
-
-    return res;
-};
-
 /**
  * Change state service : set the submission state to reviewed, needs email as input
  * http://localhost:8080/swagger-ui/index.html#/admin-controller/changeSubmissionStateReviewed
@@ -182,7 +159,6 @@ export default {
     getStatus,
     list,
     sendSubmission,
-    heartbeat,
     reviewSubmission,
     getResultPageLink,
     getLinterResult,