added optional task unique field

web/angular/src/app/messenger/messenger.ts

@@ -0,0 +1,6 @@
+export class MessengerState {
+
+    hidden: boolean;
+    message?: string;
+
+}

web/angular/src/app/messenger/snack-bar.component.ts

@@ -0,0 +1,32 @@
+import {Component, OnInit} from '@angular/core';
+import {MessengerService} from "../messenger.service";
+import {MessengerState} from "./messenger";
+import {Subscription} from "rxjs";
+import {MatSnackBar, MatSnackBarConfig} from "@angular/material";
+
+@Component({
+    selector: 'messenger-snack-bar',
+    templateUrl: 'messenger-snack-bar.html',
+    styleUrls: ['messenger-snack-bar.css'],
+})
+export class SnackBarComponent implements OnInit {
+
+    private subscription: Subscription;
+
+    constructor(private messengerService: MessengerService, private snackBar: MatSnackBar) {
+
+    }
+
+    ngOnInit() {
+        this.subscription = this.messengerService.messengerSubject
+            .subscribe((state: MessengerState) => {
+                if (state.hidden) {
+                    this.snackBar.dismiss();
+                } else {
+                    this.snackBar.open(state.message, "Close", <MatSnackBarConfig>{
+                        duration: 10 * 1000,
+                    })
+                }
+            });
+    }
+}