angular2 http request and websocket

Hi all I've an application that until now was only doing http request to retrieve data...now the problem is that we have also a websocket but I've no idea how to combine both of them:

This is my http request:

 public stock(): Observable<any> {
    if (!this._stock) {
        // rest api
        this._stock = this.http.get(url)
            .map((stock: Response) => {
                // cache the value
                stock.json().items.forEach((item) => {
                    this._stock[item.productKey] = item;
                });
                return this._stock;
            })
            .publishReplay(1)
            .refCount();
    }
    return this._stock;
}

This is the websocket:

public getStockMessages(): Observable<any> {
    return new Observable(obs => this.inventoryChannel.on(`STOCK`, (data) => {
        return obs.next(data);
    }));
}