http status code 500 / webpage stops refreshing - c#

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.

Related

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.

How to take mvc c# server errors +number to line number

Hi I've coded my MVC c# application and it's all fine, however there does seem to be a few bugs. This being one of my first applications, I'm not surprised.
The application though is internal and so I do get good feedback from the users.
They do give me the screens shots 'Server Error in ........ Application'
This gives me the controller action which does help narrow down the error.
However how do I turn the +number at end of the line to an actual line number.
I'm aware that this is some sort of byte offset, but getting a rough idea of the line number would be helpful. Is there a plugin or something I can use?
Or is there another way to handle these. I've got a Base controller that all the controllers extend from - I've seen some things that say you can use this to write to a file to give you information about the error. If I made it a generic file (similar to the php error file) then that would help me with any application I make.
You can handle server errors in Global.asax inside Application_Error() method. Create a well designed error page and save it somewhere inside your project. In global asax create a method and put error handling code inside it. See below for example code.
protected void Application_Error()
{
if (httpContext.AllErrors != null)
{
// you can handle message
var message = HttpUtility.HtmlEncode(httpContext.AllErrors[0]);
//you can redirect ugly server error page to the one you created
httpContext.Response.Redirect($"~/Error/Global");
}
}
Just developing on what hhh's answer here.
This is what I've got at the end.
protected void Application_Error()
{
if (this.Context.AllErrors != null)
{
var p = Path.Combine(Server.MapPath("~"), "Errors.log");
var message = DateTime.Now.ToString();
message = message + " " + this.Context.User.Identity.Name;
message = message + " " + this.Context.Request.Url;
message = message + Environment.NewLine;
message = message + "Post";
message = message + Environment.NewLine;
string[] keys = this.Context.Request.Form.AllKeys;
for (int i = 0; i < keys.Length; i++)
{
message = message+keys[i] + ":" + this.Context.Request.Form[keys[i]];
message = message + Environment.NewLine;
}
message = message + Environment.NewLine;
// you can handle message
message = message+ HttpUtility.HtmlEncode(this.Context.AllErrors[0]);
message = message + Environment.NewLine;
message = message + "----------------------------------";
message = message + Environment.NewLine;
System.IO.File.AppendAllText(p, message);
//you can redirect ugly server error page to the one you created
}
}
Basically giving you a file with all the key variables in the there.
Feel free to modify as you wish.

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.

jQuery post request is not sent until first post request is completed

I have a function which have a long execution time.
public void updateCampaign()
{
context.Session[processId] = "0|Fetching Lead360 Campaign";
Lead360 objLead360 = new Lead360();
string campaignXML = objLead360.getCampaigns();
string todayDate = DateTime.Now.ToString("dd-MMMM-yyyy");
context.Session[processId] = "1|Creating File for Lead360 Campaign on " + todayDate;
string fileName = HttpContext.Current.Server.MapPath("campaigns") + todayDate + ".xml";
objLead360.createFile(fileName, campaignXML);
context.Session[processId] = "2|Reading The latest Lead360 Campaign";
string file = File.ReadAllText(fileName);
context.Session[processId] = "3|Updating Lead360 Campaign";
string updateStatus = objLead360.updateCampaign(fileName);
string[] statusArr = updateStatus.Split('|');
context.Session[processId] = "99|" + statusArr[0] + " New Inserted , " + statusArr[1] + " Updated , With " + statusArr[2] + " Error , ";
}
So to track the Progress of the function I wrote a another function
public void getProgress()
{
if (context.Session[processId] == null)
{
string json = "{\"error\":true}";
Response.Write(json);
Response.End();
}else{
string[] status = context.Session[processId].ToString().Split('|');
if (status[0] == "99") context.Session.Remove(processId);
string json = "{\"error\":false,\"statuscode\":" + status[0] + ",\"statusmsz\":\"" + status[1] + "\" }";
Response.Write(json);
Response.End();
}
}
To call this by jQuery post request is used
reqUrl = "AjaxPages/lead360Campaign.aspx?processid=" + progressID + "&action=updatecampaign";
$.post(reqUrl);
setTimeout(getProgress, 500);
get getProgress is :
function getProgress() {
reqUrl = "AjaxPages/lead360Campaign.aspx?processid=" + progressID + "&action=getProgress";
$.post(reqUrl, function (response) {
var progress = jQuery.parseJSON(response);
console.log(progress)
if (progress.error) {
$("#fetchedCampaign .waitingMsz").html("Some error occured. Please try again later.");
$("#fetchedCampaign .waitingMsz").css({ "background": "url(common/images/ajax_error.jpg) no-repeat center 6px" });
return;
}
if (progress.statuscode == 99) {
$("#fetchedCampaign .waitingMsz").html("Update Status :"+ progress.statusmsz );
$("#fetchedCampaign .waitingMsz").css({ "background": "url(common/images/ajax_loded.jpg) no-repeat center 6px" });
return;
}
$("#fetchedCampaign .waitingMsz").html("Please Wait... " + progress.statusmsz);
setTimeout(getProgress, 500);
});
}
But the problem is that I can't see the intermediate message. Only the last message is been displayed after a long lime of ajax loading message
Also on the browser console I just see that after a long time first requested is completed and after that the second request is completed. but there should be for getProgress ?
I have checked jquery.doc and it says that $post is an asynchronous request.
Can anyone please explain what is wrong with the code or logic?
You are in a situation discussed here:
ASP.net session request queuing
While a request for a given user's session is processed, other requests for the same session are waiting. You need to run your long function in a background thread and let the request that initiates it finish. However, the background thread will not have access to session, and you will need a different mechanism to communicate its progress.
From the information you've provided, I would suspect that it's not your javascript code that's being synchronous, but rather the server-side code. You can test this by using Firebug or Chrome's dev tools to look at the start and end times of the two AJAX requests. If I'm right, you'll see that the second request begins after half a second, but doesn't complete until after the first one.
If that's the case, possible causes are:
Running in a dev environment in Visual Studio, especially in debug mode, seems to reduce the amount of asynchronicity. The dev environment seems to like to process one request at a time.
See Igor's answer about session request queueing.
You may have code that explicitly locks resources and causes the second request to block until the long-running request is done.
One other possible culprit is the fact that most browsers only allow a limited number of concurrent requests to a particular domain. If you have a few requests pending at any given moment, the browser may just be queuing up the remaining requests until they return.

Using webdriver PageFactory to pick certain page

I have a web project where clicking a button navigates to another page. The new page can be 1 of three possible pages depending on data in the server. (The url may be the same for 2 of those pages)
I have three classes representing expected elements on each page using the PageObject model.
What is the best way to actually find what page actually got loaded? Is there an OR type of wait that I can wait on three unique elements and get the one that actually got loaded?
Yes, it is possible to check the presence of unique element (which identifies the page) and then return respective page in the framework.
However, a test should know the page it is expecting next and should assume that the correct page has loaded and perform further actions/assertions. You can even put an assertion here to verify correct page has loaded. If a different page has loaded, then the test eventually fails as assertions would fail.
This way test becomes more readable and describes flow of application.
Also, setting up test data upfront for the tests, is always advisable. This way you would know what data is available on server and test would know which page would render.
I had a similar issue where I needed to detect if a login was for a new user (the login page then goes to a terms & conditions page rather than direct to the home page).
Initially I just waited and then tested the second page but this was just a pain so I came up with this.
To Test the result with this:
var whichScreen = waitForEitherElementText(By.CssSelector(HeaderCssUsing), "HOME SCREEN", "home", terms.getHeaderLocator(), terms.headerText, "terms", driver, MAX_STALE_RETRIES);
if(whichScreen.Item1 && whichScreen.Item2 == "terms")
{
terms.aggreeToTerms();
}
The method that this calls is :
protected Tuple<bool, string> waitForEitherElementText(By locator1, string expectedText1, string return1Ident,
By locator2, string expectedText2, string return2Ident, IWebDriver driver, int retries)
{
var retryCount = 0;
string returnText = "";
WebDriverWait explicitWait = new WebDriverWait(driver, TimeSpan.FromSeconds(globalWaitTime));
driver.Manage().Timeouts().ImplicitlyWait(TimeSpan.FromSeconds(0.5));
while (retryCount < retries)
{
try
{
explicitWait.Until<bool>((d) =>
{
try
{
if (Equals(d.FindElement(locator1).Text, expectedText1)) { returnText = return1Ident; };
}
catch (NoSuchElementException)
{
if (Equals(d.FindElement(locator2).Text, expectedText2)) { returnText = return2Ident; };
}
return (returnText != "");
});
return Tuple.Create(true, returnText);
}
catch (StaleElementReferenceException e)
{
Console.Out.WriteLine(DateTime.UtcNow.ToLocalTime().ToString() +
":>>> -" + locator1.ToString() + " OR " + locator2.ToString() + "- <<< - " +
this.GetType().FullName + "." + System.Reflection.MethodBase.GetCurrentMethod().Name +
" : " + e.Message);
retryCount++;
}
}
return Tuple.Create(false,"");
}
The explicit wait until uses a boolean so will loop around for the full wait time (I have a very slow Test server so I set this to 60 seconds). the implicit wait is set to half a second so the element tests will attempt every half a second and loop around until either true is returned or it fails.
I use a Tuple so that I can detect which screen I am on, and in this case agree to the terms & conditions which then sets me back on my normal page path

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