Uploading xml with Monotouch fails on the device - ios

Question

I am trying to send an XML via web client on Monotouch. Although everything is working on the iOS simulator I get an exception when the app is running on the device. Here is the code.
try
{
Byte[] sendData = System.Text.Encoding.UTF8.GetBytes(someXML) ;
WebClient client = new WebClient();
Byte[] forResp;
client.Headers.Add("Content-Type","text/xml");
bresp = wc.UploadData(URL, sendData);
string resp = System.Text.Encoding.ASCII.GetString(forResp);
XmlDocument xresp = new XmlDocument();
xresp.LoadXml(resp);
return xresp;
}
catch
{
// error
}
I tried the WebClient because I had the same issue with the HttpWebRequest.
Exception:
The request timed out
System.Net.WebException: The request timed out
at System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult) [0x00065] in /Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/HttpWebRequest.cs:830
at System.Net.HttpWebRequest.GetResponse () [0x0000e] in /Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/HttpWebRequest.cs:836
at System.Net.WebClient.GetWebResponse (System.Net.WebRequest request) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/WebClient.cs:1433
at System.Net.WebClient.ReadAll (System.Net.WebRequest request, System.Object userToken) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/WebClient.cs:866
at System.Net.WebClient.UploadDataCore (System.Uri address, System.String method, System.Byte[] data, System.Object userToken) [0x00038] in /Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/WebClient.cs:462
at System.Net.WebClient.UploadData (System.Uri address, System.String method, System.Byte[] data) [0x00035] in /Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/WebClient.cs:441

Answer 1

The stacktrace tells us that the timeout occurs when WebClient tries to get a response from the server (and not when uploading the data to the server). That means access to the server is not the issue (and why stacktraces are very useful ;-)
The next steps depends if you have control, or not, of the server. If you control the server then check it's logs to find the request and see how it was handled. If possible also ensure you received/decoded the data identically between the simulator and device.
If you do not control the server then it's harder to know what's going on inside it. E.g. maybe it did not like the request (i.e. the server code can decide not to answer based on any condition, including the user-agent).
In such case using a tool, like wireshark, is often your best bet. Compare the session from the iOS simulator and from the device.
Is the request identical ? e.g. the data you uploaded could be different due to something else;
Is the server answering for the device ? with the same status code ? in the same time frame ?
If everything is identical then you might have found a bug. Please report it (along with the above informations and files) to http://bugzilla.xamarin.com
Otherwise you should have more precise clues to debug the issue and/or update the question to be more specific :-)