gistfile1.cs

public class Location
{
    public double Latitude { get; set; }
    public double Longitude { get; set; }
}

public class LocationProcessor : Processor<string, string, Location>
{
    public LocationProcessor()
    {
      this.OutArguments[0].Name = "Location";
    }

    public override ProcessorResult<Location> OnExecute( string latitude, string longitude)
    {
      var lat = double.Parse(latitude);
      var lon = double.Parse(longitude);
      return new ProcessorResult<Location> { Output = new Location { Latitude = lat, Longitude = lon } };
    }
}

[ServiceContract]
public class MapResource {

  [UriTemplate="{latitude},{longitude}"]
  public Stream Get(Location location) {
    //return the map
  }
}