Re: HttpWebRequest in .NET CF 2.0 - Sent XML File over 34K Corrupted

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I'd be inclined to add a CRC to the packet and validate that what I received
is what the server sent. If the CRC fails, resend.


--

Chris Tacke, eMVP
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"Greg Hellem" <ghellem@xxxxxxxxxxx> wrote in message
news:13jjnahr9vj6ga1@xxxxxxxxxxxxxxxxxxxxx
I have a .NET CF 2.0 Mobile Application that sends "collected data" to a
HTTPS Server (running Apache under Windows 2000) and the XML file (SOAP)
containing the collected data "occasionally" appears corrupted on the
server side, but only when the XML file is greater than 34K in size, and
cannot be properly parsed as an XML Document due to missing / corrupt XML
Tags. I say "occasionally" because I cannot reproduce this error myself and
only a few of our customers (2-3 out of 70) using the mobile application
have experienced this situation. The XML file is never corrupt as long as
it is under 34K in size.

In an attempt to reproduce this error I have sent "collected data" files
as large as 125K without any XML errors and did so using various Internet
Connections, i.e. using our corporate intranet, the Internet via ADSL from
my home and using ActiveSync running on a Desktop Machine connected to our
intranet and the Internet. I have NEVER been able to reproduce this error
which led me to believe that the problem was due to hardware failures of
the mobile device itself or the customers network, but after extensive
research and testing this does not appear to be the problem either. Also,
the "collected data" itself does not contain any characters that would
violate the XML standard and I went so far as to add some code to the
mobile application that validates the XML Structure prior to sending the
data to the host server and the structure is always validated before
sending but arrives at the host server corrupted!! I am assuming that the
HTTPS / TCP/IP protocols will handle corrupt packets via the packet
checksum and request the packet again, so I don't think data is being
corrupted during its trip to the host server but instead is actually
corrupt when being transmitted from the mobile device itself, hence the
packet checksums are always correct. The mobile device is a Symbol MC3090
running WinCE 5.0 and Symbol (now Motorola) has no mention of any "data
corruption" within their knowledgebase regarding these devices.

I have read the Microsoft Article (ID 831578) regarding "Memory Leak When
SSL and Client Certificates are Used With the HttpWebRequest Object" but
am unsure if this applies to the .NET CF 2.0. We are using HTTPS / SSL and
I am using the standard example given for the
LocalCertificatePolicy.CheckValidationResult to eliminate certificate
problems such as mismatched certificate and machine names but I do not
ignore an invalid certificate.

Originally I was using .NET CF 1.1 when I created this application and ran
into a .NET CF bug regarding the use the HttpWebRequest class over HTTPS
whereby the workaround was to set AllowWriteStreamBuffering = True and to
not specify the ContentLength property. Even though the project has been
upgraded to .NET CF 2.0 I am still abiding by the workaround for the .NET
CF 1.1 bug. Is this still an issue in .NET CF 2.0?

An example of the corrupted xml data: (closing tag of
</ItemEnterpriseName> is corrupt and opening <ItemName> tag is missing
along with the data itself)
<Name>DEFAULT</Name>
<ItemEnterpriseName>Comtech Data</ItemEnterpriseNa4A</ItemName>
<SiteEnterpriseName>Comtech Data</SiteEnterpriseName>
... data continues ...

The data should have appeared as:
<Name>DEFAULT</Name>
<ItemEnterpriseName>Comtech Data</ItemEnterpriseName>
<ItemName>IC/SO-NC7SBU3157</ItemName>
<SiteEnterpriseName>Comtech Data</SiteEnterpriseName>
... data continues ...

Any assistance in the matter would be tremendously appreciated!!!
Thank you,
Greg Hellem



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