using System.ServiceModel;
using System.ServiceModel.Web;
using System.Web.Services.Protocols;

    [ServiceContract(Namespace = "http://www.123.com")]
    [ServiceBehavior(Namespace = "http://www.123.com", InstanceContextMode = InstanceContextMode.Single, AddressFilterMode = AddressFilterMode.Any)]
    [SoapDocumentService(RoutingStyle = SoapServiceRoutingStyle.RequestElement)]
    public class WebServiceHost: IWebServiceHost
    {
        [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json)]
        public string Get()
        {
            return "你好";
        }


    }

    public interface IWebServiceHost
    {
        
    }
}

using System;
using System.Security.Policy;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.Windows;

namespace WpfNetFormAddApi
{
    /// <summary>
    /// MainWindow.xaml 的交互邏輯
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        ServiceHost Host;
        private void Button_Click(object sender, RoutedEventArgs e)
        {
            Host = new ServiceHost(typeof(WebServiceHost));
            Host.OpenTimeout = TimeSpan.FromMinutes(30);
            WebHttpBinding httpBinding = new WebHttpBinding(WebHttpSecurityMode.None);
            httpBinding.MaxReceivedMessageSize = 2147483647;
            httpBinding.MaxBufferPoolSize = 2147483647;

            var endPoint = Host.AddServiceEndpoint(typeof(WebServiceHost), httpBinding, "http://localhost:7894/Index.asmx");
            WebHttpBehavior webHttpBehavior = new WebHttpBehavior();
            endPoint.Behaviors.Add(webHttpBehavior);
            Host.Open();

        }
    }
}