[Mono-bugs] [Bug 58588][Nor] New - MONO Beta 1 Bug: HTTP Unbuffered Stream Chunked-Encoding problem.
Mon, 17 May 2004 02:35:18 -0400 (EDT)
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--- shadow/58588 2004-05-17 02:35:18.000000000 -0400
+++ shadow/58588.tmp.3335 2004-05-17 02:35:18.000000000 -0400
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+Product: Mono: Class Libraries
+OS: Red Hat 9.0
+Severity: 004 Four hours
+Summary: MONO Beta 1 Bug: HTTP Unbuffered Stream Chunked-Encoding problem.
+Description of Problem:
+I have found a nasty bug in MONO Beta 1 that has been pestering me for
+some months and it is only now I have had enough time to get enough
+details to provide a full report. This bug ONLY occurs on MONO and never
+occurs on MS.NET.
+The problem started when using the MONO WSDL.exe tool to generate a proxy
+from a BEA WebLogic app server Web Service. This was reported as bug:
+58543. However I can now report more specific details about this bug, as
+it is definately a lower level HTTP bug.
+a) The bug specifically occurs when using an unbuffered XmlTextReader to
+read a large file from a BEA WebLogic web server using Chunked-encoding
+(the default). About 90% of the time the request fails, whilst 10% of
+the time it succeeds (an intermittent problem).
+b) If the XmlTextReader is replaced with a StreamReader the problem NEVER
+c) If a BufferedStream wraps the Stream (and is read by the
+XmlTextReader) the problem NEVER occurs.
+d) The problem occurs BOTH using WebClient and HttpWebRequest.
+e) If using HttpWebRequest and setting ProtocolVersion to
+HttpVersion.Version10, (HTTP 1.0) the problem NEVER occurs. I am
+assuming this is because the server is using Chunked-Encoding and HTTP
+1.0 does not support Chunked-Encoding. So I think this fixed the problem
+because chunked encoding is not being used.
+f) Front-ending the BEA Web Server with Apache also "Fixes" the problem.
+In that when Apache is proxying into WebLogic on a different port the
+problem NEVER occurs (there must be some slightly different network
+behavior between Apache and MONO when using Chunked encoding).
+Note: When using a Network Monitor or a proxy it is easy to see that the
+connection is closed before the entire request is returned from the
+server. Sometimes only 30-40% of the request is returned before MONO
+closes the connection. See the related bug report for a TCPDump.
+Note: This only happens for medium to documents (at least 100 lines or
+more). I am guessing it is something to do with the "Chatty" nature of
+Chunked-Encoding and MONO not responding in time unless the stream is
+wrapped with a buffered stream.
+Steps to reproduce the problem:
+XmlDocument doc = new System.Xml.XmlDocument();
+WebClient client = new WebClient();
+Stream stream = client.OpenRead("MyBeaServerUrl");
+XmlTextReader reader = new XmlTextReader(stream);
+Unhandled Exception: System.Xml.XmlException: Document element did not
+in <0x00250> System.Xml.XmlTextReader:Read ()
+in <0x0007b> System.Xml.XmlDocument:ReadNode (System.Xml.XmlReader)
+in <0x0004f> System.Xml.XmlDocument:Load (System.Xml.XmlReader)
+in <0x001a4> Testing.Class1:Main (string)
+This should NEVER fail and the document should be loaded into the
+instance of the XmlDocument class.
+How often does this happen?
+90% of the time when using the standard unbuffered XmlTextReader with
+HTTP 1.1 (chunked-encoding).
+I have spent MANY days trying to get this level of detail to help you
+guys resolve this bug. However I realize it will be difficult that I
+cannot directly expose the BEA instance to you (due to our production
+security guys), and front-ending it with Apache just made fixed the
+I am 99% convinced this is a nasty low-level bug in the MONO HTTP Stack.