Develop Reference

Get response from server C#

I'm trying to submit a from using c# to a website and am trying to get the response from the server as a message box after the data is sent. the website does redirect to another page to show an output.
What happens so far is the data is not submitted until I click OK on the message box that is displaying the data before it is send not after.
WebBrowser browser = new WebBrowser();
string target = "http://www.awebsite.com";
browser.Navigate(target);
browser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(XYZ);
}
}
private void XYZ(object sender, WebBrowserDocumentCompletedEventArgs e) // fail was here.
{
WebBrowser b = (WebBrowser)sender;
string text = richTextBox1.Text.ToString();
if (text == null)
{
MessageBox.Show("the messgae was empty");
}
b.Document.GetElementById("idmsg").InnerText = richTextBox1.Text.ToUpper().ToString();
b.Document.GetElementById("idpassw").InnerText = ".....";
b.Document.GetElementById("idpagers").InnerText = id;
b.Document.GetElementById("Send").InvokeMember("click");
// allow server response time
System.Threading.Thread.Sleep(5000);
string output = b.Document.Body.OuterText.ToString();
MessageBox.Show(output);
}
I'v also tried adding another Document complete with the //allow server response time code but again did'nt send till OK was pressed.
what am I doing wrong?

You do it totally wrong. Never rely on the.Sleep(...). C# provides rich enough async environment, namely Task DoAsync(...) which is to be used somewhat like await DoAsync(). This guarantees that no code going below the DoAsync() would ever be executed unless the async operation either completed successfully, either failed with error. As such, by the time you'll get to the last MessageBox.Show(...), all the data would be there, displayed properly as expected.

Clicking Retry necessary for file download with HttpResponse.WriteFile

I have a site where I'm trying to deliver files via WriteFile and they work fine in Chrome and Firefox, but in IE I have to hit "Retry" once or twice to actually make the file download.
Here is the code:
public class DownloadHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
var r = context.Response;
r.Clear();
r.ClearContent();
r.ContentType = "application/octet-stream";
string path = "";
try
{
if (HttpContext.Current.Request.QueryString["n"] != null)
{
var file = HttpContext.Current.Request.QueryString["n"].ToString();
var type = HttpContext.Current.Request.QueryString["t"].ToString();
r.AddHeader("Content-Disposition", "attachment; filename=" + file.Substring(file.IndexOf('_')+1));
string folder = "";
switch (type.ToLower())
{
case "public":
folder = ConfigurationManager.AppSettings["BCD_PublicDocsLoc"];
break;
case "private":
folder = ConfigurationManager.AppSettings["BCD_PrivateDocsLoc"];
break;
case "internal":
folder = ConfigurationManager.AppSettings["BCD_InternalDocsLoc"];
break;
}
path = folder + "/" + file;
r.WriteFile(path);
r.Flush();
r.Close();
r.End();
}
}
catch (Exception ex)
{
r.Flush();
r.Close();
r.End();
context.Response.Redirect("Error.aspx?err=301");
}
}
public bool IsReusable
{
get
{
return false;
}
}
}
If anyone has any advice as to why this is happening, it would be greatly appreciated. Thanks!

Try substituting the HttpResponse's Close() and End() calls with HttpApplication.CompleteRequest().
Read here why, there are examples too.
Also, this solution was suggested here(in the first answer) for a situation similar to yours.
As was hinted that a small explanation in this post would be convenient, due to the possibility of the links going dead in the future, here it goes:
In short: IE seems to have problems with the HttpResponse.Close and HttpResponse.End methods. Aside of that, anyways, Microsoft recommends in most cases the use of HttpApplication.CompleteRequest over the former two, because:
-HttpResponse.Close() terminates the connection abruptly, dropping buffered data and is not intended for normal HTTP use in which a response to the client is desired
-HttpResponse.End() exists for compatibility reasons with the older ASP technology. It calls the EndRequest event directly and no further code after the End call is executed which is inconvenient in many cases
-HttpApplication.CompleteRequest(): also executes the EndRequest event and it does allow the execution of the code that following the CompleteRequest call, which makes it more appropriate to handle most situations.

Just a hunch but it sounds like an I.E. caching issue to me...
if I.E is set to automatically check for newer pages 'every time i go to the website.' (in [tools\internet options\general\ browsing history\settings]) then you wont have a cache issue.
Like I say, only a hunch, but give it a whirl.
If you want to get around this [*1], add a guid to your Query string.[*2]
[*1] The cache setting is a user by user setting, you can never pre-empt the users settings, so work with them instead
[*2] The nocache value is always different, the browser will never have a cached version to go to.
I use something like this...
protected void Page_PreRender(object sender, EventArgs e)
{
if (HttpContext.Current.Request.QueryString["FirstRun"] == "1")
{
NameValueCollection nvc = HttpUtility.ParseQueryString(Request.Url.Query);
nvc.Remove("FirstRun");
string url = Request.Url.AbsolutePath;
for (int i = 0; i < nvc.Count; i++)
url += string.Format("{0}{1}={2}", (i == 0 ? "?" : "&"), nvc.Keys[i], nvc[i]);
Response.Redirect(string.Format("{1}&NoCache={0}",System.Guid.NewGuid().ToString().Replace("-",""),url));
}
}
Any links/redirects to this page need ?FirstRun=1 (or &FirstRun=1) appended to the querystring. The page reload cycles itself once adding a &noCache value to the querystring.
Note:
Because you added FirstRun=1, it will always execute twice serverside, but appear like a single load to your user, and the browser.
If you don't add FirstRun=1, it will behave like a normal request as it never gets into the condition.

http status code 500 / webpage stops refreshing

WE have an intranet webpage which is used to display information to works on monitors around our site. This webpage is automatically refreshed every 15 seconds.
All this works find, until the Database server has a problem and the webpage and no longer get a connection, and we get an error back normally an HTTP 500 error.
My solution to this has been to write a C# application that checks the HTTP status of the webpage, and if a HTTP 500 is found to close the browser and then reopen it again and display the webpage.
This application is using a timer event set to ever 30 seconds.
The problem I am having is my C# application does not always pick up the 500 error, or any other error that may cause the webpage to stop refreshing.
Below is the code I have written to try and check for the error(s)
public static void Check_Process()
{
Console.Write("checking started at {0}" + Environment.NewLine, DateTime.Now);
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(txt_url);
response = (HttpWebResponse)request.GetResponse();
// Read the error stream first and then wait.
string error = someProcess.StandardError.ReadToEnd();
Console.Write(error);
}
catch (WebException e)
{
if (e.Status == WebExceptionStatus.ProtocolError)
{
response = (HttpWebResponse)e.Response;
if ((int)response.StatusCode == 500)
{
Console.Write((int)response.StatusCode + " error found at {0}" + Environment.NewLine, DateTime.Now);
Close_webpage();
Start_webpage();
}
else if (response.StatusCode != HttpStatusCode.OK)
{
Console.Write((int)response.StatusCode + " error found at {0}" + Environment.NewLine, DateTime.Now);
Close_webpage();
Start_webpage();
}
}
}
}
The webpage is currently loaded from within the application using
public static void Start_webpage()
{
startInfo.WindowStyle = ProcessWindowStyle.Normal;
startInfo.FileName = "IExplore.exe";
startInfo.Arguments = txt_url;
someProcess = Process.Start(startInfo);
}
Hoping someone can point out where I have gone wrong, or a better way of doing this, as currently we are have to manually refresh/reload the webpage.

Do you do a complete page reload ?
How about you use ajax call instead ? You can put that in setInterval/setTimeout, and then process successful/failed responses - should make it resistant to service failures, and more user-friendly.
And yes, you probably should eliminate 500. Try/catch{msg("OMG, database is not accessible!")} type of thing :)
Ah, and the issue with your code could be the fact that your code checks database and its fine, but then the 500th user connects, and your page refresh fails.

How to synchronize writing to file in ASP.Net global.asax?

I am writing to a file, that is created for each date of the year, through code below. This code runs whenever, an unhandled exception occurs in an ASP.Net app. My problem is when many users are using the website, then this code could be hit due to several errors occurring at the same time, which could result in multiple requests to create or write to same file. What is the solution in this case so only one request executes the code related to writing to a file?
private void Application_Error(object sender, EventArgs e)
{
// Code that runs when an unhandled error occurs
string errorGuid = Guid.NewGuid().ToString("D");
if (HttpContext.Current.Server.GetLastError() != null)
{
Exception err = HttpContext.Current.Server.GetLastError();
string header = String.Format("/*****\t\t{0}:{1}\t\t*****/", "Start", errorGuid);
string footer = String.Format("/*****\t\t{0}:{1}\t\t*****/", "End", errorGuid);
string errorText = String.Format("{0}{5}Exception DateTime: {1}{5}Reference #: {2}{5}Exception:{5}=========={5}{3}{5}{4}{5}", header, System.DateTime.Now, errorGuid, err.ToString(), footer, Environment.NewLine);
// '~/ErrorReports/Logs/ErrorLog.log' must exist, else we will get an error
using (System.IO.TextWriter write = new System.IO.StreamWriter(HttpContext.Current.Server.MapPath("~/ErrorReports/Logs/ErrorLog_" + DateTime.Now.ToShortDateString() + ".log"), true, System.Text.Encoding.UTF8))
{
write.WriteLine(errorText);
write.Close();
}
}
}

1 - you can use the singleton pattern and create a class that will handle this file creation/append or
2 - use "lock"
3 - as suggested, use elmah

How to intercept when user click on a link in a webbrowser

I'm trying to intercept tapping on a link in a WebBrowser control.
My HTML page contains custom links, for some starting with shared:// I'd like to intercept when the user tap on it.
On iPhone I would use the webView:shouldStartLoadWithRequest:navigationType: method, and look at the URL that is selected.
I haven't managed to reproduce a similar behaviour with Silverlight for Windows Phone.
I do something like:
{
webBrowser1.Navigating += new EventHandler<NavigatingEventArgs>(webBrowser1_Navigating);
}
void webBrowser1_Navigating(object sender, NavigatingEventArgs e)
{
string scheme = null;
try
{
scheme = e.Uri.Scheme; // <- this is throwing an exception here
}
catch
{
}
if (scheme == null || scheme == "file")
return;
// Not going to follow any other link
e.Cancel = true;
if (scheme == "shared")
{
}
But I guess an exception when reading some properties of the Uri, when it's a standard Uri with a default file:// URL
Additionally, the Navigating event isn't even triggered for links starting with shared://
Now that I'm able to capture tapping on a shared:// I do not care much, but at least I'd like to be able to retrieve the URL we're going to navigate to, and cancel the default operation for a particular URL.
Any ideas what's going on?
Thanks
Edit:
It turned out that the problem is that the Navigating event is only generated for the following links: file://, http:// or mailto://
The scheme attributes of the Uri is only available for the http:// and mailto:// links
so what I did in the end is replace the shared:// link with http://shared/blah ... And I look at the URL... This works for my purpose. I can now have links that have a different action (like opening an extra window) depending on the links in the html.

Here is my final code, in case this is useful for someone in the future:
For an about screen, I use an html file displayed in a WebBrowser component.
The about page has a "tell your friend about this app" link as well as links to external web site.
It also has local subpages.
Local sub-pages are linked to using a file:// link. Those can be navigated within the WebBrowser component.
External links are opened externally with Internet Explorer.
Tell your friend link is made of a http://shared link, that opens an email with a pre-set subject and body. Unfortunately, no other scheme than the standard ones are usable as they do not trigger a Navigating event
There's also a support link which is a mailto:// link and opens an EmailComposeTask
void webBrowser1_Navigating(object sender, NavigatingEventArgs e)
{
String scheme = null;
try
{
scheme = e.Uri.Scheme;
}
catch
{
}
if (scheme == null || scheme == "file")
return;
// Not going to follow any other link
e.Cancel = true;
if (scheme == "http")
{
// Check if it's the "shared" URL
if (e.Uri.Host == "shared")
{
// Start email
EmailComposeTask emailComposeTask = new EmailComposeTask();
emailComposeTask.Subject = "Sharing an app with you";
emailComposeTask.Body = "You may like this app...";
emailComposeTask.Show();
}
else
{
// start it in Internet Explorer
WebBrowserTask webBrowserTask = new WebBrowserTask();
webBrowserTask.Uri = new Uri(e.Uri.AbsoluteUri);
webBrowserTask.Show();
}
}
if (scheme == "mailto")
{
EmailComposeTask emailComposeTask = new EmailComposeTask();
emailComposeTask.To = e.Uri.AbsoluteUri;
emailComposeTask.Show();
}
}