add more backend services

src/services/system.ts

@@ -0,0 +1,18 @@
+import axios from 'axios';
+import { Configuration } from './configuration';
+
+export class System {
+  static async timestamp(): Promise<number> {
+    const token = sessionStorage.getItem('token');
+    if (!token) return 0;
+
+    return axios
+      .get<number>(`${Configuration.resourceServer}/system/timestamp`, {
+        headers: {
+          Authorization: `Bearer ${token}`,
+        },
+      })
+      .then((response) => response.data)
+      .catch(() => 0);
+  }
+}