异步 Web 请求在 WCF 中不起作用答案

【问题标题】：Asynchronous web request not working in WCF异步 Web 请求在 WCF 中不起作用
【发布时间】：2017-11-09 16:27:37
【问题描述】：

我正在使用第三方API添加日志API调用，我想异步调用这个API不影响主API调用的时间，而且这个过程是低优先级的（即使API结果也不会使用。）

我尝试过以下代码，但对我来说似乎不起作用：

string strLogURL = "www.example.com";
var httpWebRequest = (HttpWebRequest)WebRequest.Create(strLogURL);
httpWebRequest.ContentType = "application/json";
httpWebRequest.Method = "POST";

using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
{
    string json = new JavaScriptSerializer().Serialize(objAPILog);            
    streamWriter.Write(json);
    streamWriter.Flush();
    streamWriter.Close();
}
httpWebRequest.BeginGetResponse(new AsyncCallback(FinishWebRequest), httpWebRequest);

谁能知道如何从 WCF 异步调用 API？

【问题讨论】：

标签： c# .net wcf asynchronous

【解决方案1】：

你可以像这样创建一个方法：

private static T Call<T>(string url, string body, int timeOut = 60)
{
    var contentBytes = Encoding.UTF8.GetBytes(body);
    var request = (HttpWebRequest)WebRequest.Create(url);

    request.Timeout = timeOut * 1000;
    request.ContentLength = contentBytes.Length;
    request.Method = "DELETE";
    request.ContentType = @"application/json";

    using (var requestWritter = request.GetRequestStream())
        requestWritter.Write(contentBytes, 0, (int)request.ContentLength);

    var responseString = string.Empty;
    var webResponse = (HttpWebResponse)request.GetResponse();
    var responseStream = webResponse.GetResponseStream();
    using (var reader = new StreamReader(responseStream))
    {
        reader.BaseStream.ReadTimeout = timeOut * 1000;
        responseString = reader.ReadToEnd();
    }

    return JsonConvert.DeserializeObject<T>(responseString);
}

然后你可以像这样异步调用它：

    Task.Run(() => Call<dynamic>("www.example.com", "body"));

【讨论】：

很高兴我能帮上忙。

【解决方案2】：

如果您只需要异步，那么您可以通过使用HttpClient 和async/await 来实现。然后你可以触发并忘记，或者在离开你的调用方法之前确保它已经完成。

public void DoSomeWork()
{
    PerformWebWork("http://example.com", new object());

    // Perform other work
    // Forget webWork Task

    // Finish
}

public async Task DoSomeWorkAsync()
{
    Task webWorkTask = PerformWebWork("http://example.com", new object());

    // Perform other work

    // Ensure webWorkTask finished
    await webWorkTask;

    // Finish
}

public async Task PerformWebWork(string url, object objAPILog)
{
    string serializedContent = new JavaScriptSerializer().Serialize(objAPILog);
    using (HttpClient client = new HttpClient())
    {
        StringContent content = new StringContent(serializedContent);
        HttpResponseMessage postResponse = await client.PostAsync(url, content);
    }
}

【讨论】：