[ServiceContract]
     [XmlSerializerFormat]
     public interface IEtermavh
     {
         [OperationContract]
         System.Xml.XmlDocument GetXml(string type, string citys, string flydate, string flytime, string aircomp, out string error);
}


     // 注意: 使用“重构”菜单上的“重命名”命令，可以同时更改代码、svc 和配置文件中的类名“Etermavh”。
     [ServiceBehavior(ConcurrencyMode=ConcurrencyMode.Multiple)]
     public class Etermavh : IEtermavh
     {
  public System.Xml.XmlDocument GetXml(string type, string citys, string flydate, string flytime, string airComp, out string error)
         {
             Comm.log(string.Format("进入。。type:{0}", type), LogType.WcfLogin);
             error = null;
             System.Threading.Thread.Sleep(10000);
　　　　　　}
　　}
//WCF服务

//客户端调用wcf服务,wcf服务已开启


   protected void Page_Load(object sender, EventArgs e)
     {
         eterm.EtermavhClient client = new eterm.EtermavhClient();
         string error;
         client.GetXml("", "", "", "", "", out error);
     }

异步也不行,也是上面的情况 
 string val;
    protected void Page_Load(object sender, EventArgs e)
    {
        Service1Client client = new Service1Client();
        IAsyncResult result = client.BeginGetData(22, back, client);
        while (!result.IsCompleted)
        {

        }
        Response.Write(val);
        //eterm.EtermavhClient client = new eterm.EtermavhClient();
        //string error;
        //client.GetXml("", "", "", "", "", out error);
    }
    private void back(IAsyncResult result)
    {
        Service1Client client = result.AsyncState as Service1Client;
        val = client.EndGetData(result);

    }