Question

Is there a standard way to read an XML file from a website that uses forms based authentication? We want to read the file into a desktop app.

thanks – dave

Answer 1

If you are talking about ASP.NET Forms Authentication this will be a two step process:

1. Send an HTTP request to the login page sending the username and password and capturing the authentication cookie sent by the server
2. Send an HTTP request to the script returning the XML file sending the authentication cookie along with the request

Here’s an example using a custom WebClient:

public class CookieAwareWebClient : WebClient
{
    public CookieContainer Cookies { get; private set; }
    public CookieAwareWebClient()
    {
        Cookies = new CookieContainer();
    }

    protected override WebRequest GetWebRequest(Uri address)
    {
        var request = base.GetWebRequest(address) as HttpWebRequest;
        request.CookieContainer = Cookies;
        return request;
    }
}

class Program
{
    static void Main()
    {
        using (var client = new CookieAwareWebClient())
        {
            client.UploadValues("http://www.foo.com/login.aspx", new NameValueCollection
            {
                { "username", "foo" },
                { "password", "secret" },
            });
            client.DownloadFile("http://www.foo.com/foo.xml", "foo.xml");
        }
    }
}

Of course in the real life things might be more complex because depending on the site you might need to send along ViewState and other ASP.NET specific crap along with the request.