example.ts

// in use
this.messageService.create('common_modal_confirm_delete', {}, 'common_button_confirm', true, "common_button_cancel")
      .subscribe(result => {
        result
          .subscribe(() => {
            this.applicant = undefined;
            this.representative = undefined;

            this.modelService.remove();
            this.loadModel();
          });
      })

// message.service.ts

  create(message: string, params?: any, acceptButtonText?: string, showDeclineButton?: boolean, declineButtonText?: string): Observable<CompleteOrErrorEmitter> {
    let translatedMessage = null;
    let translatedAcceptButtonText = null;
    let translatedDeclineButtonText = null;

    return this.translateService.get(message, params)
      .flatMap((result => {
        translatedMessage = result;

        if (acceptButtonText) {
          return this.translateService.get(acceptButtonText);
        }

        return Observable.of(null);
      }))
      .flatMap(result => {
        translatedAcceptButtonText = result;

        if (declineButtonText) {
          return this.translateService.get(declineButtonText);
        }

        return Observable.of(null);
      })
      .flatMap(result => {
        translatedDeclineButtonText = result;

        return Observable.of(this.modalDialog.show(`<h5>${translatedMessage}</h5>`, translatedAcceptButtonText, showDeclineButton, translatedDeclineButtonText));
      });
  }