如何：使用等待技术实现异步 Web 服务客户端

项目
02/28/2011

本主题专门介绍一项旧有技术。现在应通过使用以下链接来创建 XML Web 服务和 XML Web 服务客户端： Windows Communication Foundation.

等待技术是一种可实现与 Web 服务方法进行异步通信的 Web 服务客户端的方法，但该方法也可用于同步访问。将在主题“与 XML Web services 进行异步通信”中解释该技术。

此示例基于具有 Factorize 方法的 Web 服务类 PrimeFactorizer，Wsdl.exe 工具已经为该类生成了两个异步客户端代理方法：BeginFactorize 和 EndFactorize。

实现等待技术

Web 服务客户端调用生成的代理类的 Begin 方法。

IAsyncResult ar = pf.BeginFactorize(factorizableNum, null, null);

Dim ar As IAsyncResult = pf.BeginFactorize(factorizableNum, _
    Nothing, Nothing)

Web 服务客户端通过返回的 IAsyncResult 的 AsyncWaitHandle 属性访问 WaitHandle 对象。该客户端将调用 WaitHandle 类的等待方法之一，然后等待一个或多个同步对象终止。

如果客户端只是使用此技术异步调用一个 Web 服务方法，它可以调用 WaitOne，以等待该方法完成处理。其他等待方法为 WaitAny 和 WaitAll。
```
ar.AsyncWaitHandle.WaitOne();
```
```
ar.AsyncWaitHandle.WaitOne()
```
当等待方法返回时，客户端将调用 End 方法获取结果。
```
results = pf.EndFactorize(ar);
```
```
results = pf.EndFactorize(ar)
```

示例

// -----------------------------------------------------------------------// Async Variation 2.
// Asynchronously invoke the Factorize method, 
//without specifying a call back.
using System;
using System.Runtime.Remoting.Messaging;
// MyFactorize, is the name of the namespace in which the proxy class is
// a member of for this sample.
using MyFactorize;  

class TestCallback
 {          
      public static void Main(){
            long factorizableNum = 12345;
            PrimeFactorizer pf = new PrimeFactorizer();

          // Begin the Async call to Factorize.
            IAsyncResult ar = pf.BeginFactorize(factorizableNum, null, null);

          // Wait for the asynchronous operation to complete.
          ar.AsyncWaitHandle.WaitOne();

          // Get the completed results.
          long[] results;     
          results = pf.EndFactorize(ar);
          
          //Output the results.
            Console.Write("12345 factors into: ");
            int j;
            for (j = 0; j<results.Length;j++){
                  if (j == results.Length - 1)
                      Console.WriteLine(results[j]);
                  else 
                      Console.Write(results[j] + ", ");
            }
        }
}

Imports System
Imports System.Runtime.Remoting.Messaging
Imports MyFactorize     ' Proxy class namespace

Public Class TestCallback
      Public Shared Sub Main()
            Dim factorizableNum As Long = 12345
            Dim pf As PrimeFactorizer = new PrimeFactorizer()

          ' Begin the Async call to Factorize.
            Dim ar As IAsyncResult = pf.BeginFactorize(factorizableNum, Nothing, Nothing)

          ' Wait for the asynchronous operation to complete.
          ar.AsyncWaitHandle.WaitOne()

          ' Get the completed results.
          Dim results() as Long
          results = pf.EndFactorize(ar)
          
          'Output the results.
            Console.Write("12345 factors into: ")
            Dim j as Integer
            For j = 0 To results.Length - 1
                  If  j = (results.Length - 1) Then
                      Console.WriteLine(results(j) )
                  Else 
                      Console.Write(results(j).ToString + ", ")
                    End If
          Next j         
      End Sub
End Class

另请参见

通过

如何：使用等待技术实现异步 Web 服务客户端

实现等待技术

示例

另请参见

任务

概念

其他资源

其他资源