Decompression Handler

A middleware component that requests, detects and decompresses response bodies.

Requirements

• Add Accept-encoding: gzip to request headers.
• Decompress response bodies that have the header Content-Encoding: gzip
• Compression handler should be installed as a default handler by GraphClientFactory

Remarks

For request payload compression, refer to the compression handler specification.

This middleware is currently not required in JavaScript as the Fetch API already supports decompressing responses automatically and automatically adds the accept-encoding header. If Microsoft Graph accepts compressed responses at some point in the future then we should add request compression middleware to Javascript also.

Example

    public class DecompressionHandler : DelegatingHandler
    {
        protected async override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            // Declare compression support to server
            var gzipQString = new StringWithQualityHeaderValue("gzip");
            if (!request.Headers.AcceptEncoding.Contains(gzipQString))
            {
                request.Headers.AcceptEncoding.Add(gzipQString);
            }

            // Record feature usage for telemetry
            var requestContext = request.GetRequestContext();
            requestContext.FeatureUsage |= FeatureFlag.CompressionHandler;

            // Send Request
            var response = await base.SendAsync(request, cancellationToken);

            // Decompress gzipped responses
            if (response.Content != null && response.Content.Headers.ContentEncoding.Contains("gzip"))
            {
                response.Content = new StreamContent(new GZipStream(await response.Content.ReadAsStreamAsync(), CompressionMode.Decompress));
            }
            return response;
        }
    }