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Get web data by using webclient or httpRequest

I want to use webclient or httpRequest to make request on some URL. It ok if the web don't need authetication, But if website need credentical then the respond not ok. I use example code of Microsoft like below:
public class Test
{
// Specify the URL to receive the request.
public static void Main (string[] args)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create (args[0]);
// Set some reasonable limits on resources used by this request
request.MaximumAutomaticRedirections = 4;
request.MaximumResponseHeadersLength = 4;
// Set credentials to use for this request.
request.Credentials = CredentialCache.DefaultCredentials;
HttpWebResponse response = (HttpWebResponse)request.GetResponse ();
Console.WriteLine ("Content length is {0}", response.ContentLength);
Console.WriteLine ("Content type is {0}", response.ContentType);
// Get the stream associated with the response.
Stream receiveStream = response.GetResponseStream ();
// Pipes the stream to a higher level stream reader with the required encoding format.
StreamReader readStream = new StreamReader (receiveStream, Encoding.UTF8);
Console.WriteLine ("Response stream received.");
Console.WriteLine (readStream.ReadToEnd ());
response.Close ();
readStream.Close ();
}
}
Who have experience about this please help me in more detail.

HttpResponseCode has a property called StatusCode which specifies if the request has failed or succeeded. There are various status code which you can find online. But the one you are looking for is 401 which means unauthorized and 200 is for request that is successful. You can add following line after request.GetResponse() to check whether your request was successful or not.
if (response.StatusCode == HttpStatusCode.OK){
// you can continue parsing your response here.
}elseif(response.StatusCode == HttpStatusCode.Unauthorized){
// this means your request has failed due to authentication issue.
}

Call webpage from program

I would like my c# program to call a webpage when it opens. The code in the webpage will increment a counter... thus I just need the program to call the page. Don't think that I need to post or get or anything else.
Thoughts?

for more information check out msdn
// Create a request for the URL.
WebRequest request = WebRequest.Create (
"http://www.contoso.com/default.html");
// If required by the server, set the credentials.
request.Credentials = CredentialCache.DefaultCredentials;
// Get the response.
WebResponse response = request.GetResponse ();
// Display the status.
Console.WriteLine (((HttpWebResponse)response).StatusDescription);
// Get the stream containing content returned by the server.
Stream dataStream = response.GetResponseStream ();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader (dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd ();
// Display the content.
Console.WriteLine (responseFromServer);
// Clean up the streams and the response.
reader.Close ();
response.Close ();
if you can't extract the code you need from the above.. here it is
WebRequest request = WebRequest.Create ("http://www.mysite.com/counter.php?YourId");
WebResponse response = request.GetResponse();
response.Close ();

I know its late but for future people who might fall onto this.
System.Net.WebClient client = new System.Net.WebClient();
client.DownloadDataAsync(new Uri("http://stackoverflow.com"));

How to login to the android market using C#?

I would like to login to the webpage Android Market using C#. I spent the whole day reading about HTTP requests and POST data, but nothing seems to work. What I can do is read the webpage that holds the google login form. But reading the page AFTER the login seems impossible...
Can anyone give me a hint on how to do this?
BTW: The code I've tried is shown below:
string mail = "XXXXXXXXXX#gmail.com";
string pw = "XXXXXXXXXX";
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create (#"https://market.android.com/publish");
// Set the Method property of the request to POST.
request.Method = "POST";
// Create POST data and convert it to a byte array.
string postData = String.Format ("Email={0}&Passwd={1}&signIn=Sign+in", mail, pw);
byte[] byteArray = Encoding.UTF8.GetBytes (postData);
// Set the ContentType property of the WebRequest.
request.ContentType = "application/x-www-form-urlencoded";
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream ();
// Write the data to the request stream.
dataStream.Write (byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close ();
// Get the response.
WebResponse response = request.GetResponse ();
// Display the status.
Console.WriteLine (((HttpWebResponse)response).StatusDescription);
// Get the stream containing content returned by the server.
dataStream = response.GetResponseStream ();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader (dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd ();
// Display the content.
Console.WriteLine (responseFromServer);
// Clean up the streams.
reader.Close ();
dataStream.Close ();
response.Close ();

What I usually do: get live http headers for firefox and you can record the request your browser sends. Then simply repeat that in code.
for example, the android marketplace does it pretty different from your code.
it actually posts to: https://accounts.google.com/ServiceLoginAuth
And posts the data continue=https%3A%2F%2Fmarket.android.com%2Fpublish%2FHome&followup=https%3A%2F%2Fmarket.android.com%2Fpublish%2FHome&service=androiddeveloper&nui=1&dsh=&GALX=&pstMsg=1&dnConn=&timeStmp=&secTok=&Email=Passwd=&signIn=

You need to create a CookieContainer instance and assign it to the CookieContainer property in each request.
This will store the login cookie so that the site knows that you're still logged in.

How to get response from web API call

I have an API that I want to call and get the response back. Then I want to assign that response to a variable.
I have an API like:
http://example.org/Webservicesms_get_userbalance.aspx?user=xxxx&passwd=xxxx
When I run this URL in a browser, it prints an SMS balance. I want this SMS balance as a response and then assign it to a variable in my page.

You may also use WebRequest class.
WebRequest request = WebRequest.Create ("http://domainname/Webservicesms_get_userbalance.aspx?user=xxxx&passwd=xxxx");
// Get the response.
HttpWebResponse response = (HttpWebResponse)request.GetResponse ();
// Get the stream containing content returned by the server.
Stream dataStream = response.GetResponseStream ();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader (dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd ();
// Display the content.
Console.WriteLine (responseFromServer);
// Cleanup the streams and the response.
reader.Close ();
dataStream.Close ();
response.Close ();
Of course, you can change Console.WriteLine to whatever you want to do with response.

Your service is an .aspx page which just returns text (the sms balance) and no html?
If so you can 'scrape it'
string urlData = String.Empty;
WebClient wc = new WebClient();
urlData = wc.DownloadString("http://domainname/Webservicesms_get_userbalance.aspx?user=xxxx&passwd=xxxx");

finding c# ways to send http requests

I am trying to develop a Microsoft excel plugin to send excel sheet data to a web application. It will require the plugin to prompt username and password and then send login http request to the web application to get a session . Then it will upload data to the web application . What .net things should I use ?

Post Method Sample for send username and password. for uploading file just search "File Upload C#" in google.com or bing.com or try C#'s WebClient.UploadFile, Code Project
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create("http://example.com");
// Set the Method property of the request to POST.
request.Method = "POST";
// Create POST data and convert it to a byte array.
string postData = "username=user&passsword=pass";
byte[] byteArray = Encoding.UTF8.GetBytes (postData);
// Set the ContentType property of the WebRequest.
request.ContentType = "application/x-www-form-urlencoded";
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream ();
// Write the data to the request stream.
dataStream.Write (byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close ();
// Get the response.
WebResponse response = request.GetResponse ();
// Display the status.
Console.WriteLine (((HttpWebResponse)response).StatusDescription);
// Get the stream containing content returned by the server.
dataStream = response.GetResponseStream ();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader (dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd ();
// Display the content.
Console.WriteLine (responseFromServer);
// Clean up the streams.
reader.Close ();
dataStream.Close ();
response.Close();

For HTTP communication in .NET, try System.Net.WebClient or System.Net.HttpWebRequest.