使用 HttpClient 压缩对 asp.net core 2 站点的请求的最佳方法是什么？

Question

我发送的请求可能非常大（~1Mb），并且在我发出请求和 asp.net 核心记录它正在处理请求之间出现很大延迟。我想我可以通过使用 gzip 将请求压缩到 asp 来减少这个时间。

以下是我在不压缩的情况下发出请求的相当直接的方式。在客户端请求端实现Gzip请求压缩的正确方法是什么，一旦我在客户端实现它，我需要为服务器端做什么？

using (HttpResponseMessage response = client.PostAsync("Controller/Action", httpContent).Result)
{
    if (response.StatusCode != System.Net.HttpStatusCode.OK)
    {

        throw new Exception(string.Format("Invalid responsecode for http request response {0}: {1}", response.StatusCode, response.ReasonPhrase));
    }
}

Answer 1

所以我让它在服务器端使用简单的中间件，而不是在客户端做太多工作。我使用了CompressedContent.cs from WebAPIContrib，正如雷克斯在他的回答中建议的那样，并提出了如下所示的请求。整个 throw-exception-if-not-OK 是因为我使用 Polly 包裹我的请求，并带有重试和等待策略。

客户端：

using (var httpContent = new StringContent(stringPayload, Encoding.UTF8, "application/json"))
using (var compressedContent = new CompressedContent(httpContent, "gzip"))
using (HttpResponseMessage response = client.PostAsync("Controller/Action", compressedContent).Result)
{
    if (response.StatusCode != System.Net.HttpStatusCode.OK)
    {
        throw new Exception(string.Format("Invalid responsecode for http request response {0}: {1}", response.StatusCode, response.ReasonPhrase));
    }
}

然后在服务器端，我创建了一个简单的中间件，它将请求主体流与 Gzip 流包装在一起。要使用它，您需要在Startup.cs 的Configure 方法中添加app.UseMiddleware<GzipRequestMiddleware>(); 行在对app.UseMvc(); 的调用。

public class GzipRequestMiddleware
{
    private readonly RequestDelegate next;
    private const string ContentEncodingHeader = "Content-Encoding";
    private const string ContentEncodingGzip = "gzip";
    private const string ContentEncodingDeflate = "deflate";

    public GzipRequestMiddleware(RequestDelegate next)
    {
        this.next = next ?? throw new ArgumentNullException(nameof(next));
    }

    public async Task Invoke(HttpContext context)
    {
        if (context.Request.Headers.Keys.Contains(ContentEncodingHeader) && (context.Request.Headers[ContentEncodingHeader] == ContentEncodingGzip || context.Request.Headers[ContentEncodingHeader] == ContentEncodingDeflate))
        {
            var contentEncoding = context.Request.Headers[ContentEncodingHeader];
            var decompressor = contentEncoding == ContentEncodingGzip ? (Stream)new GZipStream(context.Request.Body, CompressionMode.Decompress, true) : (Stream)new DeflateStream(context.Request.Body, CompressionMode.Decompress, true);
            context.Request.Body = decompressor;
        }
        await next(context);
    }
}

Answer 2

您可能需要启用压缩，如下所示

var handler = new HttpClientHandler();  
if (handler.SupportsAutomaticDecompression)  
{
    handler.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
}

var client = new HttpClient(handler);  

MSDN 参考：Using automatic decompression with HttpClient