I changed from Client.DownloadFile to Client.DownloadFileAsync and i get exception:

[Chocolade]

I have a program that is downloading files every 3 seconds or the user time in seconds he choose. For the example of the problem its every 3 seconds.

Now it was working good without problems untill i wanted to make the downloads async. Since i changed it to async im getting exception and i cant figure out what is the problem or/and how to solve it.

So first thing in the constructor i added this line wich register me to the DownloadFileCompleted event:

Client.DownloadFileCompleted += new AsyncCompletedEventHandler(Client_DownloadFileCompleted);
 

Then i have a timer1 wich is going down for example 3 2 1...and so on...
Inside this timer1 event code im also calling a function i called it: filesdownload()

private void timer1_Tick(object sender, EventArgs e)
        {
                try
                {
                    numbers = Convert.ToInt64(textBox1.Text);
                    if (numbers <= 0)
                    {
                        timer1.Stop();
                        button1.Enabled = true;
                        textBox1.Enabled = true;
                        MessageBox.Show("Value cannot be zero or below zero");
                        textBox1.Text = "";
                    }
                    else
                    {
                        Numbers_Timer = Numbers_Timer + 1;
                        if (Numbers_Timer >= numbers)
                        {
                            try
                            {
                                filesdownload();
                                number_of_files_in_current_directory = Directory.GetFiles(sf, "radar*.jpg");
                                label8.Text = "Current Number Of Files In The Selected Directory Are: " + number_of_files_in_current_directory.Length;
                                button1.Enabled = false;
                                Numbers_Timer = 0;
                            }
                            catch (Exception Local_Timer1_Exceptions)
                            {
                                Logger.Write("Error :" + Local_Timer1_Exceptions);
                            }
                        }
                        time_left = numbers - Numbers_Timer;
                        label1.Text = "Time left for the next radar image to be download: " + time_left;
                    }
 
                }
                catch (Exception General_Exceptions)
                {
                    timer1.Stop();
                    textBox1.Clear();
                    button1.Enabled = true;
                    textBox1.Enabled = true;
                    Numbers_Timer = 0;
                }
            }
 

Now after it i have the filesdownload() function wich in there im starting to download the file every 3 seconds async!

private void filesdownload()
        {
            string url;
            url = "http://www.ims.gov.il/Ims/Pages/RadarImage.aspx?Row=9&TotalImages=10&LangID=1&Location=";
            if (!Directory.Exists(sf))
            {
                timer1.Enabled = false;
            }
 
 
                Client.DownloadFileAsync(new Uri(url), temp_dir + temp_file);
         }
 

Then in the end of my form1 code i have the Client_DownloadFileCompleted event wich in there im doing some tests and checks on the file that was download each time i mean every 3 seconds a file downloaded and the download is completed then its checking the file with some tests.

void Client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
         {
 
                 string Next_File;
                 bool file_compare;
                 int i;
                 bool bad_file;
                 progressBar1.Maximum = 10;
                 progressBar1.Minimum = 0;
                 progressBar1.TabIndex = 0;
                 progressBar1.Value = 0;
                 progressBar1.Step = 10;
                 progressBar1.PerformStep();
                 button1.Enabled = true;
                 file_array_dl = Directory.GetFiles(sf, "radar*.jpg");
                 if (file_array_dl.Length == 0)
                 {
                     File.Copy(temp_dir + temp_file, sf + @"\radar001.jpg");
                 }
                 else
                 {
                     i = last_image_file();
                     last_file = sf + @"\radar" + i.ToString("D3") + ".jpg";
                     File.Copy(last_file, bad_file_test_dir + testing_file);
                     bad_file = Bad_File_Testing(bad_file_test_dir + testing_file);
                     if (bad_file == true)
                     {
                         File.Delete(bad_file_test_dir + testing_file);
                         if (File.Exists(last_file))
                         {
                             file_compare = File_Utility.File_Comparison(temp_dir + temp_file, last_file);
                             if (file_compare == true)
                             {
                                 return;
                             }
                             i = last_image_file() + 1;
                             Next_File = sf + @"\radar" + i.ToString("D3") + ".jpg";
                             File.Copy(temp_dir + temp_file, Next_File);
                             pictureBox1.Load(Next_File); 
                                 progressBar1.Maximum = 10;
                                 progressBar1.Minimum = 0;
                                 progressBar1.TabIndex = 0;
                                 progressBar1.Value = 0;
                                 progressBar1.Step = 10;
                                 progressBar1.PerformStep();
                             button1.Enabled = true;
                         }
                     }
                     else
                     {
                         File.Delete(last_file);
                         File.Delete(bad_file_test_dir + testing_file);
                     }
 
                 }
 
                 Logger.Write("File Downloaded");
             }
 

Now when im connected to the internet the downloading is working fine no problems.
When i disconnected from the internet manualy for testing then the program dosent stuck and its keeping downloading i mean its trying to download like once counting 3 2 1 then again 3 2 1 but in the second time the seconds dosent reset back to 3 but its keeping counting 0 -1 -2 -3 -4 -5....and so on untill i stop the program.

Now i tried using breakpoints and couldnt find the problem or how to fix it.

The error/exception im getting when im disconnected from the internet is:

16/10/2010 13:09:29 -> Error :System.NotSupportedException: WebClient does not support concurrent I/O operations.
at System.Net.WebClient.ClearWebClientState()
at System.Net.WebClient.DownloadFileAsync(Uri address, String fileName, Object userToken)
at WindowsFormsApplication1.Form1.filesdownload() in D:\C-Sharp\Download File\Downloading-File-Project-Version-008\Downloading File\Downloading File\Form1.cs:line 308
at WindowsFormsApplication1.Form1.timer1_Tick(Object sender, EventArgs e) in D:\C-Sharp\Download File\Downloading-File-Project-Version-008\Downloading File\Downloading File\Form1.cs:line 265

Also another thing is when im disconnected from the internet and it keep downloading try to download im getting an error on:

Program.cs
Under the last line wich is Application.Run(new Form1()); on the closing symbol } im getting exception:

Exception has been thrown by the target of an invocation

System.Reflection.TargetInvocationException was unhandled
Message=Exception has been thrown by the target of an invocation.
Source=mscorlib
StackTrace:
at System.RuntimeMethodHandle._InvokeMethodFast(Objec t target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Delegate.DynamicInvokeImpl(Object[] args)
at System.Windows.Forms.Control.InvokeMarshaledCallba ckDo(ThreadMethodEntry tme)
at System.Windows.Forms.Control.InvokeMarshaledCallba ckHelper(Object obj)
at System.Threading.ExecutionContext.runTryCode(Objec t userData)
at System.Runtime.CompilerServices.RuntimeHelpers.Exe cuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
at System.Threading.ExecutionContext.Run(ExecutionCon text executionContext, ContextCallback callback, Object state)
at System.Windows.Forms.Control.InvokeMarshaledCallba ck(ThreadMethodEntry tme)
at System.Windows.Forms.Control.InvokeMarshaledCallba cks()
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.W ndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallba ck(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchM essageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager. System.Windows.Forms.UnsafeNativeMethods.IMsoCompo nentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.Run MessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.Run MessageLoop(Int32 reason, ApplicationContext context)
at WindowsFormsApplication1.Program.Main() in D:\C-Sharp\Download File\Downloading-File-Project-Version-008\Downloading File\Downloading File\Program.cs:line 19
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at System.Runtime.Hosting.ApplicationActivator.Create Instance(ActivationContext activationContext, String[] activationCustomData)
at Microsoft.VisualStudio.HostingProcess.HostProc.Run UsersAssemblyDebugInZone()
at System.Threading.ExecutionContext.Run(ExecutionCon text executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException: System.IO.IOException
Message=The file 'C:\Users\Chocolade\AppData\Local\Microsoft\Window sFormsApplication1\Bad_File-Test\testing_file.jpg' already exists.
Source=mscorlib
StackTrace:
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite)
at System.IO.File.Copy(String sourceFileName, String destFileName)
at WindowsFormsApplication1.Form1.Client_DownloadFile Completed(Object sender, AsyncCompletedEventArgs e) in D:\C-Sharp\Download File\Downloading-File-Project-Version-008\Downloading File\Downloading File\Form1.cs:line 1386
InnerException:



I dont know why the async dosent work and what did i do wrong.

Thanks for helping.