is-monitor/is-monitor-frontend/src/app/is.service.ts

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable, of } from 'rxjs';
import { ISType } from './ISType';
import { types } from './types';


@Injectable({
  providedIn: 'root'
})
export class IsService {

  constructor(private httpClient: HttpClient) { }

  /* NextNext Token */
  private token = '';

  /**
   * Handle Http operation that failed.
   * Let the app continue.
   * @param operation - name of the operation that failed
   * @param result - optional value to return as the observable result
   */
  private handleError<T>(operation = 'operation', result?: T) {
    return (error: any): Observable<T> => {
      console.error(error);
      console.error(`${operation} failed: ${error.message}`); // log to console instead
      // Let the app keep running by returning an empty result.
      return of(result as T);
    };
  }

  public getResourceTypes(callback: (isTypes: ISType[]) => void): void {

    const url = 'http://pc-frosini.isti.cnr.it:8080/resource-registry/types/Resource?polymorphic=true&gcube-token=' + this.token;
    // const observable: Observable<ISType[]> = of(types);
    const observable: Observable<ISType[]> = this.httpClient.get<ISType[]>(url);
    /*
    observable.pipe(
      tap(_ => console.info('Fetched Resource Types')),
      catchError(this.handleError<ISType[]>('getResourceTypes()', types))
    );
    */
    observable.subscribe(data => callback(data));
  }

}