Using session.Advanced.Stream() with IIS and HttpCompression

[Barry Hagan]

I'd like to start working with the streaming feature in 2.5, but it does not appear to work right now if you are hosted in IIS and have Raven/HttpCompression set to true (default).

I'm using build 2544 on IIS 7.5, and I get this error returned by the server when attempting to make a stream request:

[ZLibException: The stream state of the underlying compression routine is inconsistent.]

   System.IO.Compression.DeflaterZLib.Deflate(FlushCode flushCode) +8770476

   System.IO.Compression.DeflaterZLib.ReadDeflateOutput(Byte[] outputBuffer, FlushCode flushCode, Int32& bytesRead) +159

   System.IO.Compression.DeflaterZLib.System.IO.Compression.IDeflater.GetDeflateOutput(Byte[] outputBuffer) +64

   System.IO.Compression.DeflateStream.WriteDeflaterOutput(Boolean isAsync) +72

   System.IO.Compression.DeflateStream.Write(Byte[] array, Int32 offset, Int32 count) +79

   System.IO.Compression.GZipStream.Write(Byte[] array, Int32 offset, Int32 count) +33

   System.Web.HttpWriter.FilterIntegrated(Boolean finalFiltering, IIS7WorkerRequest wr) +546

   System.Web.HttpResponse.UpdateNativeResponse(Boolean sendHeaders) +1018

   System.Web.HttpResponse.Flush(Boolean finalFlush, Boolean async) +175

   System.Web.HttpWriter.WriteFromStream(Byte[] data, Int32 offset, Int32 size) +160

   System.IO.Compression.DeflateStream.PurgeBuffers(Boolean disposing) +164

   System.IO.Compression.DeflateStream.Dispose(Boolean disposing) +34

   System.IO.Stream.Close() +28

   System.IO.Compression.GZipStream.Dispose(Boolean disposing) +63

   System.IO.Stream.Close() +28

   System.Web.HttpWriter.FilterIntegrated(Boolean finalFiltering, IIS7WorkerRequest wr) +12509279

   System.Web.HttpResponse.FilterOutput() +121

   System.Web.CallFilterExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +119

   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +165

If I set Raven/HttpCompression to false for IIS or run using Raven.Server, things work as expected.

[Oren Eini (Ayende Rahien)]

I wonder if this is this:

http://issues.hibernatingrhinos.com/issue/RavenDB-961

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[Barry Hagan]

It looks like this is because the QueryStreams Responder turns off buffered output.  I'm not sure if you can apply the GZipStream filter and still make incremental writes to the output stream with IIS.  Turning off the compression made it work, as does commenting out the BufferOutput=false line, but that sort of defeats the whole intention of streaming.

There are also a couple of other issues in here:

1) No Content-Type header is set when using the JsonOutputWriter so it defaults to text/html

2) Headers are being added after writing to the output stream which cannot be done with BufferOutput=false.  This is happening with the Temp-Request-Time header, and I believe it could potentially happen with Raven-Force-Primary-Server-Check when using replication.

[Oren Eini (Ayende Rahien)]

1 & 2 are handled.

But I am not sure why there would be a problem here with IIS and unbuffered output.

In HttpListener, we aren't doing buffering, and the Gzip doesn't require it

Can you check that you aren't using Deflate instead of Gzip for some reason for compression?

[Barry Hagan]

Same thing happens if I explicitly use Gzip or Deflate.  Turning IIS compression on/off has no effect, although if I set Raven/HttpCompression to false and then modify the appplicationHost.config for IIS so it compresses "application/json; charset=utf-8" responses, then streaming works fine  with compression done by IIS rather than the response filter.  That is my workaround for now.

I have not found a way to leave context.Response.BufferOutput = false and have the GZipStream/DeflateStream filter added to the response without getting the exception when hosted in IIS7.5 or IIS Express.

[Oren Eini (Ayende Rahien)]

Okay

http://issues.hibernatingrhinos.com/issue/RavenDB-1033