Microsoft Project Online OData 异步查询

Question

我正在尝试通过在 C# 中查询数据来使用 Microsoft Project OData。我遇到性能问题，每个查询延迟大约 1 秒。我正在尝试使用该方法一次查询 2 条信息：

    public static async Task<string> ReadXml(string url)
    {
        var request = (HttpWebRequest)WebRequest.Create(url);

        request.Credentials = Credentials; // SharePointOnlineCredentials

        request.Headers.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");

        using (var response = (HttpWebResponse)await request.GetResponseAsync())
        using (var stream = response.GetResponseStream())
        using (var reader = new System.IO.StreamReader(stream))
        {
            var xml = await reader.ReadToEndAsync();

            return xml;
        }
    }

如果我调用它并且总是等待它结束后再调用它，它工作正常，但如果我一次调用它多次，我永远不会收到来自 WebRequest 的任何响应：

// just an example. I usually put a condition to filter for the tasks of a single project
var query1 = ReadXml(@"https://something.sharepoint.com/sites/pwa/_api/ProjectData/Projects");
var query2 = ReadXml(@"https://something.sharepoint.com/sites/pwa/_api/ProjectData/Tasks");
Task.WaitAll(query1, query2);

如果我“等待”第一个，然后执行第二个，它可以正常工作，但不能使用上面的代码。这是假设项目中有

谢谢，

Answer 1

根据以下帖子 Webrequest.Create 可能是问题所在，它使用了内部阻塞方法C# Thread UI is getting blocked | Possible reason WebRequest.Create?。

下面的代码使用较新的 HttpClient，应该没有这个问题。

    public static HttpClient _HttpClient { get; } = new HttpClient(new HttpClientHandler { Credentials=new NetworkCredential("","")});

    public static async Task<string> ReadXml(string url)
    {
        using (var requestMessage = new HttpRequestMessage(HttpMethod.Get, url))
        {
            requestMessage.Headers.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");
            using (var response = await _HttpClient.SendAsync(requestMessage))
            {
                return await response.Content.ReadAsStringAsync();
            }
        }
    }