/**
	 * get data from the server
	 * @param url: string
	 * @returns Observable observable
	 */
	get(url)
	{
		var subject = new Subject();

		this.checkAccessToken().then(
			() => {
				let headers = new Headers();
				this.createAuthorizationHeader(headers);

				this._http.get(url, {
					headers: headers
				}).subscribe(subject);
			}
		);

		return subject;
	}