异步调用Web Service

VS2008、C#

今天发现，在.NET 3.5下，异步调用Web Service与以往似乎有些不同。现在生成的代理类少了 BeginXXX 方法，Why?

1. Web Service

[WebMethod]
         public   string  GetUserName()  {
            return "zhenglanzhen";
        }

2. 同步调用

class  Program  {
        static void Main(string[] args) {
            Console.WriteLine("step1");
            NameServiceProxy.NameService n = new NameServiceProxy.NameService();
            Console.WriteLine(n.GetUserName());
            Console.WriteLine("step2");
            Console.Read();
        }
    }

输出：
step1

zhenglanzhen

step2

3. 异步调用

class  Program  {
        static void Main(string[] args) {
            Console.WriteLine("step1");
            NameServiceProxy.NameService n = new NameServiceProxy.NameService();
            n.GetUserNameCompleted += delegate(object sender, GetUserNameCompletedEventArgs e) {
                Console.WriteLine(e.Result);
            };
            n.GetUserNameAsync();
            Console.WriteLine("step2");
            Console.Read();
        }
    }

输出：

step1

step2

zhenglanzhen