从 .NET 6 HttpClient 调用 SOAP 操作 - 出现错误

问：

我需要根据我拥有的规范调用SOAP操作。我已经创建了SOAP消息，需要发送它。我已配置，但每次发送帖子消息时，我都会收到“服务不可用”响应状态。HttpClient

我已经测试了从 SOAPUI 调用 SOAP 服务操作并且它有效。我错过了什么？HttpClient

以下是服务提供商提供的 HTTP 标头规范：

POST https://soap.msg-qa.com
HTTP/1.1
Accept-Encoding: gzip,deflate
Content-Type: application/soap+xml;charset=”UTF8”;action="QuoteRealTime" 
Content-Length: 3108
Host: soap.msg-qa.com
Connection: Keep-Alive
User-Agent: Apache-HttpClient/4.1.1 (java 1.5

代码如下：

HttpClientHandler handler = new HttpClientHandler();
handler.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
using (var client = new HttpClient(handler))
{
    client.Timeout = new TimeSpan(0, 2, 0);
              
    var request = new HttpRequestMessage()
                {
                    RequestUri = new Uri("https://soap.msg-qa.com"),
                    Method = HttpMethod.Post
                };

    request.Content = new StringContent(soapmessage, Encoding.UTF8, "text/xml");

    request.Headers.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/xml"));

    request.Content.Headers.ContentType = new MediaTypeHeaderValue("text/xml");
    request.Headers.Add("SOAPAction", "QuoteRealTime");

    HttpResponseMessage response = client.SendAsync(request).Result;

    if (!response.IsSuccessStatusCode)
    {
        _logger.LogError($"result = {response.StatusCode}, message = {response.ReasonPhrase}");
        return null;
    }
    else
    {
        _logger.LogInformation($"Success. result = {response.StatusCode}, message = {response.ReasonPhrase}");
        return "";
    }
}