HTTP Headers Request reduction

The requests generated by the HTTP_Client were a bit chunky with user-agent strings, content type etc.

Accept: */*
Accept-Language: en
User-Agent: NETMFToolbox/0.1 (textmode; Netduino; IntegratedSocket; HTTP_Client)
x-Pos: 5C-86-4A-00-3F-63 20130130080711 F -43.00000 172.00000 16.9 1.28 0 0
Content-Type: application/x-www-form-urlencoded
Content-Length: 0
Connection: Close

I then modified the HTTP_Client so that the accept, accept language, user agent, and content Type headers could be removed if not necessary.

x-Pos: 5C-86-4A-00-3F-63 20130130081228 F -43.00000 172.00000 31.4 1.31 0 0
Content-Length: 0
Connection: Close

This reduced the size of the request down to 186 bytes which was comparable with the smallest System.http HTTPRequest. But, the durations looked a bit odd..

Average duration 1317 mSec

This was roughly 200mSec slower than the larger request version. After some digging I think the TCP socket was buffering (Nagle algorithm send coalescing) the send.

I then modified IntegratedSocket.cs connect method to disable this buffering

EndPoint Destination = new IPEndPoint(address.AddressList[0], (int)this._Port);
// Connects to the socket
this._Sock.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);

I then checked the request durations again

10 requests to
Average duration 983 mSec

10 requests to IP Address
584, 595,578,597,581,595,577,593,580,599
Average duration 588 mSec

These were faster than any of the results with the baked in HttpWebRequest in System.http.

So I fired up .Net Reflector and had a look at the decompiled System.http code and though there are calls socket.SetSocketOption in EstablishConnection I can’t see any way for a user to set the NoDelay socket option as allowWriteStreamBuffering appears not to be used.

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