How to compress http request on the fly and without loading compressed buffer in memory

Question

I need to send voluminous data in a http post request to a server supporting gziped encoded requests.

Starting from a simple

public async Task<string> DoPost(HttpContent content)
{
  HttpClient client = new HttpClient();
  HttpResponseMessage response = await client.PostAsync("http://myUri", content);

  response.EnsureSuccessStatusCode();
  return await response.Content.ReadAsStringAsync();
}

I've just added a pre compression

public async Task<string> DoPost(HttpContent content, bool compress)
{
  if (compress) 
    content= await CompressAsync(content);

  return await DoPost(content);
}

private static async Task<StreamContent> CompressAsync(HttpContent content)
{
  MemoryStream ms = new MemoryStream();
  using (GZipStream gzipStream = new GZipStream(ms, CompressionMode.Compress, true))
  {
    await content.CopyToAsync(gzipStream);
    await gzipStream.FlushAsync();
  }

  ms.Position = 0;
  StreamContent compressedStreamContent = new StreamContent(ms);
  compressedStreamContent.Headers.ContentType = content.Headers.ContentType;
  compressedStreamContent.Headers.Add("Content-Encoding", "gzip");

  return compressedStreamContent;
}

It works perfectly but compress data are completly loaded into memory before sending request. I would like to be able to compress data on the fly during sending in a streaming way.

To do it, I've tried following code:

private static async Task<HttpContent> CompressAsync2(HttpContent content)
{
  PushStreamContent pushStreamContent = new PushStreamContent(async (stream, content2, transport) =>
  {
    using (GZipStream gzipStream = new GZipStream(stream, CompressionMode.Compress, true))
    {
      try
      {
        await content.CopyToAsync(gzipStream);
        await gzipStream.FlushAsync();
      }
      catch (Exception exception)
      {
        throw;
      }
    }
  });
  pushStreamContent.Headers.ContentType = content.Headers.ContentType;
  pushStreamContent.Headers.Add("Content-Encoding", "gzip");

  return pushStreamContent;
}

but it never goes out of CopyToAsync(gzipStream). FlushAsync is never executed and no exception is thrown and Fiddler don't see any post started.

My questions are:

• Why CompressAsync2 doesn't work?
• How to compress on the fly during sending and without loading compressed buffer in memory?

Any help would be greatly appreciated.

Answer 1

Try using the CompressedContent class from WebAPIContrib https://github.com/WebApiContrib/WebAPIContrib/blob/master/src/WebApiContrib/Content/CompressedContent.cs

public async Task<string> DoPost(HttpContent content)
{
  HttpClient client = new HttpClient();
  HttpResponseMessage response = await client.PostAsync("http://myUri", 
                                 new CompressedContent(content,"gzip"));

  response.EnsureSuccessStatusCode();
  return await response.Content.ReadAsStringAsync();
}

P.S. that this will only stream the content on .net 4.5. The .net 4 version of HttpWebRequest always buffers sent content.

P.P.S. Creating a new HttpClient for each request is not the best way to use HttpClient. Doing this will force a new TCP connection to be created for each request.