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connect client to server and get a text file from it in C#

I would like to connect automatically from a client to a server with an IP address in C# and get a text file from the server.
What would be the best way to achieve this ?

WebClient
The simplest way to do so is using "WebClient". See https://msdn.microsoft.com/en-us/library/system.net.webclient(v=vs.110).aspx
This class has a function called
public string DownloadString(string address)
You can use this to download the text file to memory.
For more Methods (e.g. DownloadFile) visit the given link. Note: This Method might hang the window if executed in the UI-Thread while downloading the content. Either use a second Thread to do the stuff or use the asynchronous methods if possible.
In this case you would rather use this:
public Task<string> DownloadStringTaskAsync(string address)
More Information about Async: https://msdn.microsoft.com/en-us/library/dd537609(v=vs.110).aspx

It is easy to achieve using a WebRequest as follows.
// Create a request for the URL.
WebRequest request = WebRequest.Create("http://yourdomain.com/textfile");
// Get the response.
WebResponse response = 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();

HttpWebResponse text does not appear to be JSON

I am making a rest call in which I get a HttpWebResponse that contains data. It seems the data is serialized, and I am trying to get the plain text of the request. I have been using the chrome extension Advanced Rest client, which when calling the same request it is able to display the text version of the json response.
From what I have read on here, you are required to deserialize into the expected object. However, it is pretty clear that chrome plugin has no idea about the object type and can still print out plain text.
Is it possible to do the same in c#?
HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;
request.Method = "POST";
request.ContentType = "application/json";
// [code removed for setting json data via stream writer
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
// This is where I am trying to figure out how to get plain readable text out of response.GetResponseStream()
}
Edit: If I simply use a StreamReader to get the text from the response stream, I get a bunch of binary data and not the plain json text.
Edit: realized the problem had to do with compression. This can be closed.

I'm not sure if got it right, but you can get the response as a string doing this:
using (var sr = new StreamReader(response.GetResponseStream()))
{
text = sr.ReadToEnd();
}

Turned out my problem was due to compression. I realized the header contained "Content-Encoding: gzip" so I searched on how to unzip with gzip compression and then the text was proper json. Thanks all

Communicating with an ASP website

I have a know a website that contains an open database of the result of an academic test.
http://nts.org.pk/NTSWeb/PPL_30Sep2012_Result/search.asp
I am expert with C# but newbie to web development.
Usually, using web browser, we can enter and roll number and server sends back the result. E.G. Use my Roll Num: 3912125
What I need to do is, use a C# application to communicate this roll null number and get anything, of my result. (any string is excepted, I will parse out my result from that string.)
How do I send query? when I don't know a list of possible query strings.
I tried this code:
string queryString = "RollNo=3912125";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(#"http://nts.org.pk/NTSWeb/PPL_30Sep2012_Result/search.asp");
request.UseDefaultCredentials = true;
request.ContentType = "application/x-www-form-urlencoded";
request.Method = "POST";
byte[] requestBytes = Encoding.UTF8.GetBytes(queryString);
request.ContentLength = requestBytes.Length;
using (var requestStream = request.GetRequestStream())
{
requestStream.Write(requestBytes, 0, requestBytes.Length);
requestStream.Close();
}
WebResponse response = request.GetResponse();
textBox1.AppendText(((HttpWebResponse)response).StatusDescription);
Stream dataStream = response.GetResponseStream();
StreamReader reader = new StreamReader(dataStream);
string responseFromServer = reader.ReadToEnd();
textBox1.AppendText(responseFromServer);
reader.Close();
dataStream.Close();
response.Close();

You have to append the querystring to the url like this:
string queryString = "RollNo=3912125";
string url = String.Format(#"http://foo/search.asp?{0}", queryString);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

You should take a look at the code in my answer to C# https login and download file. It gives a good demonstration of how to perform a POST request. As far as knowing what's valid to use for the query-formatted string in your POST, it's simply a matter of looking for appropriate input elements in the page content. It looks like what you have (RollNo) is correct. You may, however, need to also add the submit button value to your request as well depending on how the server behaves, giving you something like. RollNo=3912125&submit=submit.

You're most of the way there. Your queryString should look like RollNo=3912125&Submit=+Search+. When you are calling WebRequest.Create, the Url should in fact be http://nts.org.pk/NTSWeb/PPL_30Sep2012_Result/result.asp.
The rest of your code should work, though the answer #JamieSee recommended to you has some very good advice about wrapping things in using blocks correctly

POST Data to PHP Page Using C# in Place of Form URL

I have an C# cart application that needs to POST some data to a PHP page and redirect the user to that page to view the data. Everything is working fine! So, what is the problem??
Since we are using a Javascript function to POST the form to the PHP page through setting its action to the PHP URL, it is not allowing us to clear our Session variable with our cart contents.
Once the user clicks checkout and is sent to the third party site, we want our session variable that stores their cart contents to go away. To my knowledge I cannot clear this via the Javascript, so my idea was to send the POST data and the user to the PHP page through the C# code.
When the user clicks checkout, the Javascript reloads the page, sets the cart data to a string variable, clears the session, then POSTs the data and sends the user to the PHP page.
All of this is working, except for the POST of data and redirecting the user. Unfortunately, the third party page cannot accept a URL.PHP?=var type parameter for security reasons, so we have to POST it.
Using WebRequest I believe I can get the data posted, but I cannot get the user redirected to that page to finish out their order. Any ideas?

I recommend you implement an intermediary page to prepare the data and cleanup the Session for you. The 'checkout' link would simply navigate the user to this intermediary page, which would do the following:
Collect the user's cart data out of the session
Clear the session
POST to the PHP page using WebRequest
From the MSDN on WebRequest:
using System;
using System.IO;
using System.Net;
using System.Text;
namespace Examples.System.Net
{
public class WebRequestPostExample
{
public static void Main ()
{
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create ("http://www.contoso.com/PostAccepter.aspx ");
// Set the Method property of the request to POST.
request.Method = "POST";
// Create POST data and convert it to a byte array.
string postData = "This is a test that posts this string to a Web server.";
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 ();
}
}
}

You can keep on using the Javascript solution and just add a Ajax call that will abandon the session

I am only speculating here but you should be able to transmit the data in a WebBrowser control item, that way it would send the post data and redirect.

Reading and posting to web pages using C#

I have a project at work the requires me to be able to enter information into a web page, read the next page I get redirected to and then take further action. A simplified real-world example would be something like going to google.com, entering "Coding tricks" as search criteria, and reading the resulting page.
Small coding examples like the ones linked to at http://www.csharp-station.com/HowTo/HttpWebFetch.aspx tell how to read a web page, but not how to interact with it by submitting information into a form and continuing on to the next page.
For the record, I'm not building a malicious and/or spam related product.
So how do I go read web pages that require a few steps of normal browsing to reach first?

You can programmatically create an Http request and retrieve the response:
string uri = "http://www.google.com/search";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
// encode the data to POST:
string postData = "q=searchterm&hl=en";
byte[] encodedData = new ASCIIEncoding().GetBytes(postData);
request.ContentLength = encodedData.Length;
Stream requestStream = request.GetRequestStream();
requestStream.Write(encodedData, 0, encodedData.Length);
// send the request and get the response
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
// Do something with the response stream. As an example, we'll
// stream the response to the console via a 256 character buffer
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
Char[] buffer = new Char[256];
int count = reader.Read(buffer, 0, 256);
while (count > 0)
{
Console.WriteLine(new String(buffer, 0, count));
count = reader.Read(buffer, 0, 256);
}
} // reader is disposed here
} // response is disposed here
Of course, this code will return an error since Google uses GET, not POST, for search queries.
This method will work if you are dealing with specific web pages, as the URLs and POST data are all basically hard-coded. If you needed something that was a little more dynamic, you'd have to:
Capture the page
Strip out the form
Create a POST string based on the form fields
FWIW, I think something like Perl or Python might be better suited to that sort of task.
edit: x-www-form-urlencoded

You might try Selenium. Record the actions in Firefox using Selenium IDE, save the script in C# format, then play them back using the Selenium RC C# wrapper. As others have mentioned you could also use System.Net.HttpWebRequest or System.Net.WebClient. If this is a desktop application see also System.Windows.Forms.WebBrowser.
Addendum: Similar to Selenium IDE and Selenium RC, which are Java-based, WatiN Test Recorder and WatiN are .NET-based.

What you need to do is keep retrieving and analyzing the html source for each page in the chain. For each page, you need to figure out what the form submission will look like and send a request that will match that to get the next page in the chain.
What I do is build a custom class the wraps System.Net.HttpWebRequest/HttpWebResponse, so retrieving pages is as simple as using System.Net.WebClient. However, my custom class also keeps the same cookie container across requests and makes it a little easier to send post data, customize the user agent, etc.

Depending on how the website works you can either manipulate the url to perform what you want. e.g to search for the word "beatles" you could just open a request to google.com?q=beetles and then just read the results.
Alternatively if the website does not use querystring values (url) to process page actions then you will need to work on a webrequest which posts the required values to the website instead. Search in Google for working with WebRequest and webresponse.