如何使.Net web-API能够接受g-ziped帖子

Question

我有一个相当重要的标准.net MVC 4 Web API应用程序.

 public class LogsController : ApiController
{

    public HttpResponseMessage PostLog(List<LogDto> logs)
    {
        if (logs != null && logs.Any())
        {
            var goodLogs = new List<Log>();
            var badLogs = new List<LogBad>();

            foreach (var logDto in logs)
            {
                if (logDto.IsValid())
                {
                    goodLogs.Add(logDto.ToLog());
                }
                else
                {
                    badLogs.Add(logDto.ToLogBad());
                }
            }

            if (goodLogs.Any())
            {
                _logsRepo.Save(goodLogs);
            }

            if(badLogs.Any())
            {
                _logsBadRepo.Save(badLogs);
            }


        }
        return new HttpResponseMessage(HttpStatusCode.OK);
    }
}

这一切都很好,我有能够发送他们的日志的设备,它运作良好.但是现在我们开始担心要传输的数据的大小,我们想看一下接受使用GZIP压缩的帖子？

我该怎么做呢？是在IIS中设置还是我可以使用Action Filters？

编辑1

跟着菲利普的回答,我的想法是我需要在它到达我的控制器之前拦截请求的处理.如果我可以在Web api框架尝试将请求的主体解析到我的业务对象之前捕获请求,该请求失败,因为请求的主体仍然被压缩.然后我可以解压缩请求的主体,然后将请求传递回处理链,希望Web Api框架能够将(解压缩的)主体解析为我的业务对象.

它看起来像使用DelagatingHandler是要走的路.它允许我在处理期间,但在我的控制器之前访问请求.所以我尝试了下面这个？

 public class gZipHandler : DelegatingHandler
{

    protected override System.Threading.Tasks.Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
    {
        string encodingType = request.Headers.AcceptEncoding.First().Value;

        request.Content = new DeCompressedContent(request.Content, encodingType);

        return base.SendAsync(request, cancellationToken);
    }
}

public class DeCompressedContent : HttpContent
{
    private HttpContent originalContent;
    private string encodingType;

    public DeCompressedContent(HttpContent content, string encodType)
    {
        originalContent = content;
        encodingType = encodType;
    }

    protected override bool TryComputeLength(out long length)
    {
        length = -1;

        return false;
    }


    protected override Task<Stream> CreateContentReadStreamAsync()
    {
        return base.CreateContentReadStreamAsync();
    }

    protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
    {
        Stream compressedStream = null;

        if (encodingType == "gzip")
        {
            compressedStream = new GZipStream(stream, CompressionMode.Decompress, leaveOpen: true);
        }

        return originalContent.CopyToAsync(compressedStream).ContinueWith(tsk =>
        {
            if (compressedStream != null)
            {
                compressedStream.Dispose();
            }
        });
    }



}

}

这似乎工作正常.在我的控制器和正在调用DecompressedContent的构造函数之前调用SendAsync方法.但是从不调用SerializeToStreamAsync,所以我添加了CreateContentReadStreamAsync以查看是否应该在哪里进行解压缩,但是也没有调用.

我觉得我接近解决方案,但只需要一点点额外就可以了解它.

Answer 1

我有同样的要求将gzip压缩数据发送到.NET web api控制器.我想出了这个解决方案:

public class GZipToJsonHandler : DelegatingHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,
                                                           CancellationToken cancellationToken)
    {
        // Handle only if content type is 'application/gzip'
        if (request.Content.Headers.ContentType == null ||
            request.Content.Headers.ContentType.MediaType != "application/gzip")
        {
            return base.SendAsync(request, cancellationToken);
        }

        // Read in the input stream, then decompress in to the outputstream.
        // Doing this asynronously, but not really required at this point
        // since we end up waiting on it right after this.
        Stream outputStream = new MemoryStream();
        Task task = request.Content.ReadAsStreamAsync().ContinueWith(t =>
            {
                Stream inputStream = t.Result;
                var gzipStream = new GZipStream(inputStream, CompressionMode.Decompress);

                gzipStream.CopyTo(outputStream);
                gzipStream.Dispose();

                outputStream.Seek(0, SeekOrigin.Begin);
            });

        // Wait for inputstream and decompression to complete. Would be nice
        // to not block here and work async when ready instead, but I couldn't 
        // figure out how to do it in context of a DelegatingHandler.
        task.Wait();

        // This next section is the key...

        // Save the original content
        HttpContent origContent = request.Content;

        // Replace request content with the newly decompressed stream
        request.Content = new StreamContent(outputStream);

        // Copy all headers from original content in to new one
        foreach (var header in origContent.Headers)
        {
            request.Content.Headers.Add(header.Key, header.Value);
        }

        // Replace the original content-type with content type
        // of decompressed data. In our case, we can assume application/json. A
        // more generic and reuseable handler would need some other 
        // way to differentiate the decompressed content type.
        request.Content.Headers.Remove("Content-Type");
        request.Content.Headers.Add("Content-Type", "application/json");

        return base.SendAsync(request, cancellationToken);
    }
}

使用此方法,现有的控制器(通常使用JSON内容和自动模型绑定)继续工作而不进行任何更改.

我不确定为什么其他答案被接受了.它提供了处理响应的解决方案(这是常见的),但不是请求(这是不常见的).Accept-Encoding标头用于指定可接受的响应编码,与请求编码无关.

Answer 2

我相信正确的答案是Kaliatech,我会留下这个作为评论并投票他的我有足够的声望点,因为我认为他基本上是正确的.

但是,我的情况要求需要查看编码类型类型而不是内容类型.使用这种方法,调用系统仍然可以指定内容类型中的内容类型是json/xml/etc,但是指定使用gzip或可能的其他编码/压缩机制对数据进行编码.这使我无需在解码输入后更改内容类型,并允许任何内容类型信息以其原始状态流过.

这是代码.同样,其中99%是Kaliatech的答案,包括评论,所以如果有用的话,请将他的帖子投票.

public class CompressedRequestHandler : DelegatingHandler
{
    protected override System.Threading.Tasks.Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
    {
        if (IsRequetCompressed(request))
        {
            request.Content = DecompressRequestContent(request);
        }

        return base.SendAsync(request, cancellationToken);
    }

    private bool IsRequetCompressed(HttpRequestMessage request)
    {
        if (request.Content.Headers.ContentEncoding != null &&
            request.Content.Headers.ContentEncoding.Contains("gzip"))
        {
            return true;
        }

        return false;
    }

    private HttpContent DecompressRequestContent(HttpRequestMessage request)
    {
        // Read in the input stream, then decompress in to the outputstream.
        // Doing this asynronously, but not really required at this point
        // since we end up waiting on it right after this.
        Stream outputStream = new MemoryStream();
        Task task = request.Content.ReadAsStreamAsync().ContinueWith(t =>
            {
                Stream inputStream = t.Result;
                var gzipStream = new GZipStream(inputStream, CompressionMode.Decompress);

                gzipStream.CopyTo(outputStream);
                gzipStream.Dispose();

                outputStream.Seek(0, SeekOrigin.Begin);
            });

        // Wait for inputstream and decompression to complete. Would be nice
        // to not block here and work async when ready instead, but I couldn't 
        // figure out how to do it in context of a DelegatingHandler.
        task.Wait();

        // Save the original content
        HttpContent origContent = request.Content;

        // Replace request content with the newly decompressed stream
        HttpContent newContent = new StreamContent(outputStream);

        // Copy all headers from original content in to new one
        foreach (var header in origContent.Headers)
        {
            newContent.Headers.Add(header.Key, header.Value);
        }

        return newContent;
    }

然后我在全球注册了这个处理程序,如果你容易受到DoS攻击,这可能是一个冒险的主张,但是我们的服务被锁定了,所以它适用于我们

GlobalConfiguration.Configuration.MessageHandlers.Add(new CompressedRequestHandler());

Answer 3

虽然Web API不支持Accept-Encoding开箱即用的标题,但Kiran有一篇关于如何做到这一点的博客文章 - http://blogs.msdn.com/b/kiranchalla/archive/2012/09/04/handling- compression-accept-encoding-sample.aspx - 使用自定义MessageHandler

如果您实现了他的解决方案,您需要做的就是发出带有Accept-Encoding: gzip或者Accept-Encoding: deflate头的请求,Web API响应将在消息处理程序中为您压缩.