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WebClient returning an XDocument

Posted on 2011-09-21
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Last Modified: 2013-12-27
I'm writing a simple Windows Mobile application (my first) and just want to be sure of how best to obtain data from a web service.  Actually I'm not using a Web Service as such just a web page as I want to later port to Android so want to stay away from Microsoft specific functionality if I can.

My first problem.question is how best to return an XDocument from a web page being used as a service.  My code here is :-

XDocument xDocument = new XDocument();
xDocument.Declaration = new XDeclaration("1.0", "utf-8", "");
XElement xMainElement = new XElement("whereabouts");
xDocument.Add(xMainElement);

// Check login parameters
string username = Request.QueryString["uid"];

// Build Document

// return document
Response.Write(xDocument);

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This is in page_load - essentially I want to return some data to the windows mobile WebClient to say if the user logged in or not.  The problem here is that I get the web page text following the XML - I assume that I just need to add Reponse.End() after the write but just want to be sure.

In the Windows Mobile Client I am using WebClient.OpenReadSync.  In my read completed function I have the following code L-

 
XDocument xDocument = new XDocument();
xDocument.Declaration = new XDeclaration("1.0", "utf-8", "");
XElement xMainElement = new XElement("whereabouts");
xDocument.Add(xMainElement);

// Check login parameters
string username = Request.QueryString["uid"];

// Build Document

// return document
Response.Write(xDocument);

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Is this correct or is there a better way of getting the returned XML into an XDocument - I did try loading straight from the stream but this gave an error.
Stream reply = null;
StreamReader stream = null;

try
{
 reply = e.Result;
 stream = new StreamReader(reply);

// Read the reply into an XDocument
  string xml = stream.ReadToEnd();
  XDocument jobsDocument = XDocument.Load(xml);

}
finally
{
// Close the stream reader and stream
  if (stream != null)
	stream.Close();
  if (reply != null)
       reply.Close ();
}

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Question by:ChrisMDrew
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8 Comments
 
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Expert Comment

by:Mikal613
ID: 36574445
For your serice:

XmlTextReader reader = new XmlTextReader(YOUR_XML_URL);

            // Supply the credentials necessary to access the Web server.
            XmlUrlResolver resolver = new XmlUrlResolver();
            resolver.Credentials = CredentialCache.DefaultCredentials;
            reader.XmlResolver = resolver;
 
            _xd.Load(reader);

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Author Comment

by:ChrisMDrew
ID: 36574497
I have seen that you can load directly like that however I really need to use Async mode I believe to prevent hanging the phone waiting for a reply from the server.  

As such I am using the WebClient.OpenReadAsync rather than going direct as you suggest.

the Response.End has helped - I also had to change the code in the web page to return the data as

Response.Write(xDocument.Declaration.ToString() + xDocument.ToString());
Response.End();

Oddly enough when I load into the XDocument at the phone end I still get an error stating that it 'cannot find file'???
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LVL 48

Expert Comment

by:Mikal613
ID: 36574506
What Mobile OS are you using?
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Author Comment

by:ChrisMDrew
ID: 36574637
Windows Mobile 7 - I think I have cracked the original question though - when i write the XDocument I need to use :-


Response.Write( @"<?xml version='1.0' encoding='utf-8'?>" + xDocument.ToString());
Response.End();

at the other end I use :-

string xml = stream.ReadToEnd();
XDocument jobsDocument = XDocument.Parse(xml);

which appears to work - is this the best way to do this however?

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LVL 48

Expert Comment

by:Mikal613
ID: 36574700
When you add the web reference to the mobile project it automatically add the Async calls for you.
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Author Comment

by:ChrisMDrew
ID: 36576889
...but as I metioned at the start - I don't want to use Web References / services (at least not the Microsoft .NET implementation) as I want to be able to port to Android at some stage.

Actually working fine as per my last comment - now for some LINQ questions...
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Expert Comment

by:Mikal613
ID: 36577193
Yes you can use the web client to DownloadSrring()
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Accepted Solution

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Mikal613 earned 500 total points
ID: 36580052
using System.Net;
using System.Xml;
using System.Threading;
using System.Xml.Linq;

 WebClient wc = new WebClient();
 wc.DownloadStringCompleted +=new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);
 wc.DownloadStringAsync(new Uri("PathToYourXML")));


void  wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
      XDocument _xd;
     _xd = XDocument.Parse(e.Result, LoadOptions.None);
}
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