C# Multiple http requests same PHP session

Question

I'm trying to get the picture to load in the same PHP session in which the POST request will be sent. But because i'm using button1_Click this is not possible. And the outcome is to get the picture to load before the data is sent. If you got any questions please ask.

i know i go wrong with the picture loading, but i dont know exactly where..

using visual c# 2010 express winforms

private void Form1_Load(object sender, EventArgs e)
    {
        pictureBox1.ImageLocation = "http://localhost/proj/guess-my-fav/1.jpg";
    }
    private void button1_Click(object sender, EventArgs e)
    {
        Uri uri = new Uri("http://localhost/proj/guess-my-fav/level14.php");
        var answer = textBox1.Text;
        string data = "guess=" + answer + "&level=14&time=opt";
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
        request.Method = WebRequestMethods.Http.Post;
        request.CookieContainer = new CookieContainer();
        request.KeepAlive = true;
        request.ContentLength = data.Length;
        request.ContentType = "application/x-www-form-urlencoded";
        StreamWriter writer = new StreamWriter(request.GetRequestStream());
        writer.Write(data);
        writer.Close();
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        StreamReader reader = new StreamReader(response.GetResponseStream());
        string tmp = reader.ReadToEnd();
        response.Close();
        richTextBox1.AppendText(tmp); // log - delete this line          
    }

How can i put the rendering of image under the second request?

Answer 1

pictureBox1.ImageLocation = "http://localhost/proj/guess-my-fav/1.jpg";

This is going to cause the client's browser to make a request for 1.jpg

Uri uri = new Uri("http://localhost/proj/guess-my-fav/level14.php");
...
HttpWebResponse response = (HttpWebResponse)request.GetResponse();

This is going to cause the webserver running the ASP.NET website to make a request for level14.php

You're not going to get those two requests using the same session since they'll be coming from two different machines!

You might like to look into moving that HttpWebRequest code out of the back end, and reimplementing it on the client side as an AJAX request. Then both requests will be coming from the client's browser.

Answer 2

If you modify your code to match

 private CookieContainer cookieContainer;

        private void Form1_Load(object sender, EventArgs e)
        {

            var wr = (HttpWebRequest)WebRequest.Create("http://localhost/proj/guess-my-fav/1.jpg");
            cookieContainer = new CookieContainer();
            wr.CookieContainer = this.cookieContainer;
            var resp = (HttpWebResponse)wr.GetResponse();
            wr.CookieContainer = cookieContainer;
            using (var s = resp.GetResponseStream())
            {
                pictureBox1.Image = new Bitmap(s);
            }
        }



private void button1_Click(object sender, EventArgs e)
    {
        Uri uri = new Uri("http://localhost/proj/guess-my-fav/level14.php");
        var answer = textBox1.Text;
        string data = "guess=" + answer + "&level=14&time=opt";
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
        request.Method = WebRequestMethods.Http.Post;
        request.CookieContainer = cookieContainer;
        request.KeepAlive = true;
        request.ContentLength = data.Length;
        request.ContentType = "application/x-www-form-urlencoded";
        StreamWriter writer = new StreamWriter(request.GetRequestStream());
        writer.Write(data);
        writer.Close();
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        StreamReader reader = new StreamReader(response.GetResponseStream());
        string tmp = reader.ReadToEnd();
        response.Close();
        richTextBox1.AppendText(tmp); // log - delete this line          
    }

This should make both requests to the server using the same session.

Hope this helps.

Answer 3

I am assuming here that you want to re-load the image when you click the button.

First of all that ImageLocation property is probably not gonna respect your session cookie, so you might have to download the image manually. You already used a CookieContainer so that's a good start.

What we want to do here is use a new HttpWebRequest to download the image and attach the same CookieContainer to it as this one should hold the session id after your first call. We can then use the HttpWebResponse to create an Image object and assign this to the pictureBox1.Image property.

All this together might look something like this:

private void button1_Click(object sender, EventArgs e)
{
    Uri uri = new Uri("http://localhost/proj/guess-my-fav/level14.php");
    var answer = textBox1.Text;
    string data = "guess=" + answer + "&level=14&time=opt";

    CookieContainer cookies = new CookieContainer(); /* we want to have this for other call also

    HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
    request.Method = WebRequestMethods.Http.Post;
    request.CookieContainer = cookies;
    request.KeepAlive = true;
    request.ContentLength = data.Length;
    request.ContentType = "application/x-www-form-urlencoded";
    StreamWriter writer = new StreamWriter(request.GetRequestStream());
    writer.Write(data);
    writer.Close();
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    StreamReader reader = new StreamReader(response.GetResponseStream());
    string tmp = reader.ReadToEnd();
    response.Close();
    richTextBox1.AppendText(tmp); // log - delete this line 

    HttpWebRequest request2 = (HttpWebRequest)HttpWebRequest.Create("http://localhost/proj/guess-my-fav/1.jpg");
    request2.CookieContainer = cookies;
    HttpWebResponse response2 = (HttpWebResponse)request.GetResponse();
    pictureBox1.Image = Image.LoadFromStream(response2.GetResponseStream());

}