Before connection to the server we need to check minimal supported version

src/app/components/servers/add-server-dialog/add-server-dialog.component.ts

@@ -4,6 +4,7 @@ import { Server } from '../../../models/server';
 import { ElectronService } from 'ngx-electron';
 import { FormGroup, FormControl, Validators } from '@angular/forms';
 import { ServerService } from '../../../services/server.service';
+import { ToasterService } from '../../../services/toaster.service';
 
 
 @Component({
@@ -30,6 +31,7 @@ export class AddServerDialogComponent implements OnInit {
     public dialogRef: MatDialogRef<AddServerDialogComponent>,
     private electronService: ElectronService,
     private serverService: ServerService,
+    private toasterService: ToasterService,
     @Inject(MAT_DIALOG_DATA) public data: any,
   ) {}
 
@@ -145,7 +147,21 @@ export class AddServerDialogComponent implements OnInit {
     }
 
     const server: Server = Object.assign({}, this.serverForm.value);
-    this.dialogRef.close(server);
+    this.serverService.checkServerVersion(server).subscribe(
+      (serverInfo) => {
+        if ((serverInfo.version.split('.')[1]>=2) && (serverInfo.version.split('.')[0]>=2)) {
+          this.dialogRef.close(server);
+          this.toasterService.success(`Server ${server.name} added.`)
+        } else {
+          this.dialogRef.close();
+          this.toasterService.error(`Server version is not supported.`)
+        }
+      },
+      error => { 
+        this.dialogRef.close();
+        this.toasterService.error('Cannot connect to the server.')
+      }
+    );
   }
 
   onNoClick(): void {

src/app/components/servers/servers.component.ts

@@ -39,7 +39,17 @@ export class ServersComponent implements OnInit, OnDestroy {
           server.status = 'running';
         }
       });
-      this.serverDatabase.addServers(servers);
+
+      servers.forEach((server) => {
+        this.serverService.checkServerVersion(server).subscribe(
+          (serverInfo) => {
+            if ((serverInfo.version.split('.')[1]>=2) && (serverInfo.version.split('.')[0]>=2)) {
+              if (!this.serverDatabase.find(server.name)) this.serverDatabase.addServer(server);
+            }
+          },
+          error => {}
+          );
+      });
     });
 
     this.dataSource = new ServerDataSource(this.serverDatabase);

src/app/services/project.service.ts

@@ -2,7 +2,6 @@ import { Injectable } from '@angular/core';
 import { Project } from '../models/project';
 import { Node } from '../cartography/models/node';
 import { Observable } from 'rxjs';
-
 import { Link } from '../models/link';
 import { Server } from '../models/server';
 import { HttpServer } from './http-server.service';

src/app/services/server.service.spec.ts

@@ -5,6 +5,8 @@ import { Server } from '../models/server';
 import { IndexedDbService } from './indexed-db.service';
 import { AngularIndexedDB } from 'angular2-indexeddb';
 import Spy = jasmine.Spy;
+import { HttpServer, ServerErrorHandler } from '../services/http-server.service';
+import { HttpClient } from '@angular/common/http';
 
 export class MockedServerService {
   public servers: Server[] = [];
@@ -46,6 +48,7 @@ describe('ServerService', () => {
   let db: AngularIndexedDB;
   let service: ServerService;
   let openDatabaseSpy: Spy;
+  let httpServer = new HttpServer({} as HttpClient, {} as ServerErrorHandler);
 
   beforeEach(() => {
     indexedDbService = new IndexedDbService();
@@ -55,7 +58,11 @@ describe('ServerService', () => {
     openDatabaseSpy = spyOn(db, 'openDatabase').and.returnValue(Promise.resolve(true));
 
     TestBed.configureTestingModule({
-      providers: [ServerService, { provide: IndexedDbService, useValue: indexedDbService }]
+      providers: [
+        ServerService, 
+        { provide: IndexedDbService, useValue: indexedDbService },
+        { provide: HttpServer, useValue: httpServer }
+      ]
     });
 
     service = TestBed.get(ServerService);

src/app/services/server.service.ts

@@ -1,14 +1,18 @@
 import { Injectable } from '@angular/core';
-
 import { IndexedDbService } from './indexed-db.service';
 import { Server } from '../models/server';
+import { Observable } from 'rxjs';
+import { HttpServer } from './http-server.service';
 
 @Injectable()
 export class ServerService {
   private tablename = 'servers';
   private ready: Promise<any>;
 
-  constructor(private indexedDbService: IndexedDbService) {
+  constructor(
+    private indexedDbService: IndexedDbService,
+    private httpServer: HttpServer
+  ) {
     this.ready = indexedDbService.get().openDatabase(1, evt => {
       evt.currentTarget.result.createObjectStore(this.tablename, { keyPath: 'id', autoIncrement: true });
     });
@@ -59,6 +63,10 @@ export class ServerService {
     return `http://${server.host}:${server.port}/`;
   }
 
+  public checkServerVersion(server: Server): Observable<any> {
+    return this.httpServer.get(server, '/version');
+  }
+
   public getLocalServer(host: string, port: number) {
     const promise = new Promise((resolve, reject) => {
       this.findAll().then((servers: Server[]) => {