Rx Multiple Services

    public class AirlineNamesService
    {
        private readonly Uri _serviceUrl;

        public AirlineNamesService()
        {
            _serviceUrl = new Uri("http://flydata.avinor.no/airlineNames.asp");
        }

        public IObservable<Airline> GetAirlines()
        {
            return WebRequestFactory.GetData(_serviceUrl, ParseAirlineXml);
        }

        private static IEnumerable<Airline> ParseAirlineXml(XmlReader reader)
        {
            var xml = XDocument.Load(reader);

            return from airlineNames in xml.Elements("airlineNames")
                   from airline in airlineNames.Elements("airlineName")
                   select new Airline
                              {
                                  Code = airline.Attribute("code").Value,
                                  Name = airline.Attribute("name").Value
                              };
        }
    }

    public class AirportNamesService
    {
        private readonly Uri _serviceUrl;

        public AirportNamesService()
        {
            _serviceUrl = new Uri("http://flydata.avinor.no/airportNames.asp");    
        }

        public IObservable<Airport> GetAirports()
        {
            return WebRequestFactory.GetData(_serviceUrl, ParseAirportXml);
        }

        private static IEnumerable<Airport> ParseAirportXml(XmlReader reader)
        {
            var xml = XDocument.Load(reader);

            return from airportNames in xml.Elements("airportNames")
                   from airport in airportNames.Elements("airportName")
                   select new Airport
                              {
                                  Code = airport.Attribute("code").Value,
                                  Name = airport.Attribute("name").Value
                              };
        }
    }

    public class FlightsService
    {
        private readonly string _serviceUrl;
        private readonly string _direction;
        private readonly string _lastUpdate;

        private Dictionary<string, Airport> _airports;
        private Dictionary<string, Airline> _airlines;
        private Dictionary<string, FlightStatus> _statuses;


        public FlightsService()
        {
            _serviceUrl = "http://flydata.avinor.no/XmlFeed.asp?TimeFrom={0}&TimeTo={1}&airport={2}";
            _lastUpdate = "&lastUpdate=2009-03-10T15:03:00";
            _direction = "&direction={0}";

            _airports = new Dictionary<string, Airport>();
            _airlines = new Dictionary<string, Airline>();
        }
        
        public IObservable<Flight> GetFlightsFrom(Airport a)
        {
            var airports = new AirportNamesService().GetAirports();
            var airlines = new AirlineNamesService().GetAirlines();
            var statuses = new FlightStatusesService().GetStautses();
  

            string url = string.Format(_serviceUrl, 1, 7, a.Code);            
            return GetFlightsFrom(url);
        }

        private static IObservable<Flight> GetFlightsFrom(string url)
        {
            return WebRequestFactory.GetData(new Uri(url), ParseFlightsXml);
        }

        private static IEnumerable<Flight> ParseFlightsXml(XmlReader reader)
        {
            var xml = XDocument.Load(reader);

            return from airport in xml.Elements("airport")
                   from flights in airport.Elements("flights")
                   from flight in flights.Elements("flight")
                   select new Flight
                              {
                                  UniqueId = flight.AttributeValueOrEmpty("uniqueID"),
                                  Gate = flight.ElementValueOrEmpty("gate"),
                                  Direction = ConvertToDirection(flight.Element("arr_dep")),
                                  LastLeg = ConvertToFlightArea(flight.Element("dom_int")),
                                  ScheduledTime = flight.ElementAsDateTime("schedule_time")
                              };
        }

        private static Direction ConvertToDirection(XElement element)
        {
            if(element == null) return Direction.Depature;
            return element.Value == "D" ? Direction.Depature : Direction.Arrival;
        }

        private static FlightArea ConvertToFlightArea(XElement element)
        {
            if(element == null) return FlightArea.Domestic;
            if (element.Value == "S") return FlightArea.Schengen;
            if (element.Value == "I") return FlightArea.International;            
            return FlightArea.Domestic;            
        }
    }