Communicating with the web through a C# app?

Question

Although i can grasp the concepts of the .Net framework and windows apps, i want to create an app that will involve me simulating website clicks and getting data/response times from that page. I have not had any experience with web yet as im only a junior, could someone explain to me (in english!!) the basic concepts or with examples, the different ways and classes that could help me communicate with a website?

Answer 1

You could use the System.Net.WebClient class of the .NET Framework. See the MSDN documentation here.

Simple example:

using System;
using System.Net;
using System.IO;

public class Test
{
    public static void Main (string[] args)
    {
        if (args == null || args.Length == 0)
        {
            throw new ApplicationException ("Specify the URI of the resource to retrieve.");
        }

        WebClient client = new WebClient ();

        // Add a user agent header in case the 
        // requested URI contains a query.

        client.Headers.Add ("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");

        Stream data = client.OpenRead (args[0]);
        StreamReader reader = new StreamReader (data);
        string s = reader.ReadToEnd ();
        Console.WriteLine (s);
        data.Close ();
        reader.Close ();
    }
}

There are other useful methods of the WebClient, which allow developers to download and save resources from a specified URI.

The DownloadFile() method for example will download and save a resource to a local file. The UploadFile() method uploads and saves a resource to a specified URI.

UPDATE:

WebClient is simpler to use than WebRequest. Normally you could stick to using just WebClient unless you need to manipulate requests/responses in an advanced way. See this article where both are used: http://odetocode.com/Articles/162.aspx

Answer 2

what do you want to do?

send a request and grab the response in a String so you can process?

HttpWebRequest and HttpWebResponse will work

if you need to connect through TCP/IP, FTP or other than HTTP then you need to use a more generic method

WebRequest and WebResponse

All the 4 methods above are in System.Net Namespace

If you want to build a Service in the web side that you can consume, then today and in .NET please choose and work with WCF (RESTfull style).

hope it helps you finding your way :)

as an example using the HttpWebRequest and HttpWebResponse, maybe some code will help you understand better.

case: send a response to a URL and get the response, it's like clicking in the URL and grab all the HTML code that will be there after the click:

private void btnSendRequest_Click(object sender, EventArgs e)
{
    textBox1.Text = "";
    try
    {
        String queryString = "user=myUser&pwd=myPassword&tel=+123456798&msg=My message";
        byte[] requestByte = Encoding.Default.GetBytes(queryString);

        // build our request
        WebRequest webRequest = WebRequest.Create("http://www.sendFreeSMS.com/");
        webRequest.Method = "POST";
        webRequest.ContentType = "application/xml";
        webRequest.ContentLength = requestByte.Length;

        // create our stram to send
        Stream webDataStream = webRequest.GetRequestStream();
        webDataStream.Write(requestByte, 0, requestByte.Length);

        // get the response from our stream
        WebResponse webResponse = webRequest.GetResponse();
        webDataStream = webResponse.GetResponseStream();

        // convert the result into a String
        StreamReader webResponseSReader = new StreamReader(webDataStream);
        String responseFromServer = webResponseSReader.ReadToEnd().Replace("\n", "").Replace("\t", "");

        // close everything
        webResponseSReader.Close();
        webResponse.Close();
        webDataStream.Close();

        // You now have the HTML in the responseFromServer variable, use it :)
        textBox1.Text = responseFromServer;
    }
    catch (Exception ex)
    {
        textBox1.Text = ex.Message;
    }
}

The code does not work cause the URL is fictitious, but you get the idea. :)