Using the Exited event in vb.net - vb.net

Ok, I'm making a very basic vb.net winforms app, essentially you can drag files into it, and it then uses a batch file to process the files.
It's pretty simple and everything is going to plan so far, it accepts the right files, it uses the batch file to process them and the batch file does what it is supposed to.
The only problem is that I don't know how to hook into the Exited event that can/should be raised by the batch file process when the process completes...
I want the DOS window of the batch file to remain hidden while it is running, so I have used ProcessStartInfo to specify the batch file, then set the WindowStyle property of the process to ProcessWindowStyle.Minimised, then used System.Diagnostics.Process.Start(myBatch) to start the process at the appropriate moment.
This is fine, it works and does what I want. However, the only way to tell when a process ends is to use the Exited event. But the Exited event apparently only works with a Process not a ProcessStartInfo. I could switch to use Process instead but then I couldn't (AFAIK) run the DOS window minimised...
Is there a way around this? I've only been writing .net for a few days. This is how I'm running the batch file:
Dim myBatch As New ProcessStartInfo("C:\\batchFiles\\test.bat")
myBatch.WindowStyle = ProcessWindowStyle.Minimized
system.Diagnostics.Process.Start(myBatch)
Any ideas?
Thanks

Try creating a process object and setting the StartInfo property. You can then call WaitForExit instead of waiting for the event. EG:
using(var process = new Process
{
StartInfo =
new ProcessStartInfo("Foo.exe")
{WindowStyle = ProcessWindowStyle.Minimized}
})
{
process.Start();
process.WaitForExit();
}

Not sure of the syntax in VB but I am almost sure that what you have to do is actually use the WIN API inline with managed code, and then you can use the MainWindowHandle of the Process Object.
[DllImport("User32")]
private static extern int ShowWindow(int hwnd, int nCmdShow);
The commands it takes, I would recommend reference to the win api library for this method. But what you want to do I would think is very feasible with the interop.
Andrew

From the documentation: This event can occur only if the value of the EnableRaisingEvents property is true.
So the following should work:
Dim procStart As New ProcessStartInfo
Dim WithEvents proc As New Process
Private Sub Button21_Click(sender As System.Object, e As System.EventArgs) Handles Button21.Click
procStart.FileName = "C:\PTL\Bin\xxxxxx.exe"
proc.StartInfo = procStart
proc.EnableRaisingEvents = True
proc.Start()
End Sub
Private Sub proc_Exited(sender As Object, e As System.EventArgs) Handles proc.Exited
Debug.WriteLine("Process Ended " + proc.ExitCode.ToString + " " + DateTime.Now.ToString)
End Sub

Related

Using Filewatcher for a progress bar with subdirectories, Wont Update Properly

I'm trying to copy Files from a local Computer to a Network device. I'm trying to get a Progress Bar working for the File copy, and got it working for a Single Directory with no Subdirectory:
Private Sub CopyPictures()
Try
If Not Directory.Exists(DestinationPath) Then
My.Computer.FileSystem.CreateDirectory(DestinationPath)
End If
Dim counterLocalFiles = My.Computer.FileSystem.GetFiles(SourcePath)
UpdateProgressBarMaximum1(CInt(counterLocalFiles.Count))
UpdateLabelText2(CStr(counterLocalFiles.Count)) 'is a label which shows copied X files of Label2 Files
fsw1 = New IO.FileSystemWatcher(DestinationPath)
fsw1.EnableRaisingEvents = True
My.Computer.FileSystem.CopyDirectory(SourcePath, DestinationPath)
GetSettingsFromFile()
Catch Exec As System.IO.IOException
Dim dr As DialogResult = MessageBox.Show("Some Random Error Code", "Exception Title", MessageBoxButtons.OKCancel)
If (Not DialogResult.OK = dr) Then
Exit Sub
Return
End If
End Try
End Sub
Private Sub fsw1_Created(sender As Object, e As FileSystemEventArgs) Handles fsw1.Created
Dim counterRemoteFiles = My.Computer.FileSystem.GetFiles(DestinationPath)
UpdateProgressBar1(CInt(counterRemoteFiles.Count))
UpdateLabelText1(CStr(counterRemoteFiles.Count))
End Sub
The Update ObjectX Subs are just invoke Functions since the CopyPictures is raised by a backgroundworker as well looking all like this one for example
Private Sub UpdateProgressBar1(Value As Int32)
If ProgressBar1.InvokeRequired Then
ProgressBar1.Invoke(New Action(Of Integer)(AddressOf UpdateProgressBar1), Value)
Else
'We are on the UI thread so update the control.
ProgressBar1.Value = Value
End If
End Sub
This code works perfectly fine for me, but I have to deal with SubDirectories which contain the Images, and the names of the subs are random so i cant predetermine them so I came up with slight changes:
The Counter is looking now like this:
Dim counterLocalFiles = System.IO.Directory.GetFiles(SourcePath, "*.jpg*", SearchOption.AllDirectories).Length
UpdateProgressBarMaximum1(CInt(counterLocalFiles))
UpdateLabelText2(CStr(counterLocalFiles))
And this:
Dim counterRemoteFiles = IO.Directory.GetFiles(DestinationPath, "*.jpg", SearchOption.AllDirectories).Length
UpdateProgressBar1(CInt(counterRemoteFiles))
UpdateLabelText1(CStr(counterRemoteFiles))
And I added:
fsw1.IncludeSubdirectories = True
Now the weired Problems started: It would properly count the file in the source Directory setting label2 to the correct amount of files in all subdirectories and then start copying. It would NOT update the Progressbar though in real time. It just updated it once when it was done with the first directory and just adding the amount of files to it which it contained. After that it completly stoppedd nored the second directory and didn't add that at all to the progressbar. What am I doing wrong here? I hope my english is fine, If you have any question or If I was not clear enough, please let me know. Thank you
You don't have an event consumer that triggers your progressbar update routine - you call it once when your filesystemwatcher is instantiated.
You need to declare an event that handles the copy event and fires off your progress update code. Because Filesystemwatcher cannot monitor network drives, you may want to declare an event that fires off your progress update method when the counterRemoteFiles count increments.
Turns out I just made a mistake with correctly putting the
fsw1.IncludeSubdirectories = True
I was setting it to true in the Form Editor instead of doing it in the code. Once i actually put that in the code after initialising the fsw, it would work just fine

ActiveReports not allowing overwrite of jpg after report generation. Windows. VB.NET

Currently, I am utilizing ActiveReports to implement a dynamic image via pathname into a report that is generating.
The Images are being automatically generated as .jpg to a server folder. The Active Reports module imports the files using this code.
Sub ActiveReport_ReportStart
Picture1.Image = System.Drawing.Image.FromFile("path\filename.jpg")
End Sub
The problem I am running into is that this report locks out the jpgs from being overwritten.
I am unsure what could be going wrong, but it seems that the report is still using the image files after the report has been generated.
Am I missing a "disconnect" code piece to ensure that an import doesn't allow for continued contact to the file?
I apologize if this is simple, but I can't find anything for this specific instance.
Thank you.
EDIT:
I attempted to get around the lockout by copying them into their own variable. But this didn't work either.
Sub ActiveReport_ReportStart
dim TempImage as Image = Image.FromFile("path\filename")
Picture1.Image = TempImage
End Sub
You can use "Using" block to make sure that the object of the image is disposed as soon as its usage is completed.
Using statement basically marks a boundary for the objects specified in the statement. So when code block using Using – End Using is exited either after normal execution or some exception cause, the framework invokes the Dispose method of these objects automatically.
Here is the suggested code which can be helpful for you in resolving the issue:
Private Sub SectionReport1_ReportStart(sender As Object, e As EventArgs) Handles MyBase.ReportStart
Dim img As Image
Using bmpTemp = New Bitmap("path\filename.jpg")
img = New Bitmap(bmpTemp)
End Using
Picture1.Image = img
End Sub
I was able to get this to work by creating a function that used the Graphics.FromImage method and disposed the original file.
Public Function GetImageFile(ByVal pathfn As String) As Image
Dim tempImg As Image = Image.FromFile(pathfn)
Dim tempBtm As New Bitmap(Width:=img.Width*CorrectFactor, Height:=img.Height*CorrectFactor, Format:=tempImg.PixelFormat)
Using g As Graphics = Graphics.FromImage(bm)
g.DrawImage(tempImg, Point.Empty)
End Using
tempImg.Dispose()
Return tempBtm
End Function
The item that would be placed in the report would be as follows.
Sub ActiveReport_ReportStart
Picture1.Image = GetImageFile("Path\Filename")
End Sub

Detect when exe is started vb.net

Dose anybody know how I can make my VB.net application wait until a process is detected as running?
I can find example of how to detect once an exe has finished running but none that detect when an exe is started?
You can use the System.Management.ManagementEventWatcher to wait for certain WMI events to occur. You need to give it a query type and condition to have it watch for the next creation of your process, then get it to do something when that occurs.
For example, if you want :
Dim watcher As ManagementEventWatcher
Public Sub Main()
Dim monitoredProcess = "Notepad.exe"
Dim query As WqlEventQuery = New WqlEventQuery("__InstanceCreationEvent", new TimeSpan(0, 0, 1), "TargetInstance isa ""Win32_Process"" And TargetInstance.Name = """ & monitoredProcess & """")
watcher = New ManagementEventWatcher()
watcher.Query = query
'This starts watching asynchronously, triggering EventArrived events every time a new event comes in.
'You can do synchronous watching via the WaitForNextEvent() method
watcher.Start()
End Sub
Private Sub Watcher_EventArrived(sender As Object, e As EventArrivedEventArgs) Handles watcher.EventArrived
'Do stuff with the startup event
End Sub
Eventually you'll need to stop the watcher, which is you can do by closing the app, or calling watcher.Stop(). This has been written as brain compiler, so if there's any issues let me know.
You could simply wait and check every once in a while whether the process exists. Use Thread.Sleep to avoid busy waiting.
However, this has the possibility that you miss the process if it starts and exists during your wait time.
You can use the below condition
return Process.GetProcesses().Any(Function(p) p.Name.Contains(myProcessName))
Dim p() As Process
Private Sub CheckIfRunning()
p = Process.GetProcessesByName("processName")
If p.Count > 0 Then
' Process is running
Else
' Process is not running
End If
End Sub
OR SIMPLY
System.Diagnostics.Process.GetProcessesByName("processName")

Download a file from the web periodically

I am creating an application which on startup (MainWindow loaded) starts a BackgroundWorker, which on DoWork checks whether there is a newer version of the file (DatasSource for an Autocompletebox) available. If so, I download and merge this with the existing file and create a new file.
Now I want to do this on startup and also periodically (like 30 minutes). So I created a threading.Timer [it's a private member in MainWindow class] and initialize it in RunWorkerCompleted of the backgroundWorker (as mentioned above). The timer goes to the callback successfully but at the file download code (just a fyi, a different namespace and different class) it just terminates and I can't figure out why?
I have tried using Windows.Timers.Timer, ThreadPool.RegisterWaitForSingleObject() but no luck...
Can anyone point me to the right direction? I am open to any solution.
Download code:
Public Sub MergeHistoryFile()
/*Check the directory if there are any downloaded files(.tmp);if there are;just delete them*/
/*some code which checks if file on web is modified;if yes download file*/
Try
Dim waiter As Threading.AutoResetEvent = New AutoResetEvent(False)
_downloader = New WebClient()
AddHandler _downloader.DownloadDataCompleted, AddressOf Me.DownloaderFileCompleted
_downloader.DownloadDataAsync(New Uri(path_file), waiter)
waiter.WaitOne()
Catch ex As Exception
Throw ex
End Try
/*some more code which checks if there something new in the downloaded file;if yes merge the local and the downloaded file reinitialize the autocomplebox*/
End Sub
Private _downloadCancelled As Boolean = False
Private Sub DownloaderFileCompleted(ByVal sender As Object, ByVal e As System.Net.DownloadDataCompletedEventArgs)
If IsNothing(e.Error) Then
If Not (IsNothing(e.Result)) Then
Using fs As New FileStream(Path.Combine(HistoryPath, "_tempDownladedFile.tmp"), FileMode.CreateNew)
fs.Write(e.Result, 0, e.Result.Count)
End Using
CType(e.UserState, Threading.AutoResetEvent).Set()
End If
Else
_downloadCancelled = True
_downloader.CancelAsync()
End If
End Sub
There are several problems with this code, as I pointed out in my comment.
I think your primary problem is that when you create the file, you're passing FileMode.CreateNew, which is going to fail if the file already exists. As the documentation says:
CreateNew Specifies that the operating system should create a new file. This requires FileIOPermissionAccess.Write permission. If the file already exists, an IOException exception is thrown.
You probably want FileMode.Create.
So what happens is that the FileStream constructor throws an exception, which causes your DownloadFileCompleted method to exit without ever setting the event that tells the caller to stop waiting.

VB.NET/WMI - Real-Time Windows Service Monitoring?

So there's an application at my work that installs several Windows services to a server. As a side project, I've been asked to make a simple GUI that will list these services with a "light" (a picture box with a red or green dot) next to the name of each service. The idea is that in the event these services were to stop running, the "light" would change from green to red.
I have the GUI part built, and I can query a remote server's services, then compare it to an array of the ones I'm interested and set the "light" next to each service to green/red depending on the service state. The part I'm hung up on is how to monitor these services in real time? Currently, I just have the following code in the Form_Load event:
Dim myConnectionOptions As New System.Management.ConnectionOptions
With myConnectionOptions
.Impersonation = System.Management.ImpersonationLevel.Impersonate
.Authentication = System.Management.AuthenticationLevel.Packet
End With
Try
Dim myManagementScope As System.Management.ManagementScope
myManagementScope = New System.Management.ManagementScope("\\" & SERVERNAME & "\root\cimv2", myConnectionOptions)
myManagementScope.Connect()
Dim query As New Management.ObjectQuery("SELECT * FROM Win32_Service")
Dim searcher As New Management.ManagementObjectSearcher(myManagementScope, query)
Dim i As Integer = 0
For Each queryObj As Management.ManagementObject In searcher.Get()
For Each service As String In arrServices
If queryObj("DisplayName").Equals(service) Then
If queryObj("State").Equals("Stopped") Then
arrLights(i).Image = My.Resources.redlight
End If
i += 1
End If
Next
Next
Catch err As Management.ManagementException
MessageBox.Show("WMI query failed with the following error: " & err.Message)
Catch unauthorizedErr As System.UnauthorizedAccessException
MessageBox.Show("Authentication error: " & unauthorizedErr.Message)
End Try
Would a simple timer that executes this code repeatedly be the best approach, or is there a more elegant solution? I have a little experience in VB.NET and WMI, but none in any type of real-time monitoring activity like this.
First of all i would put it into a thread, that way even if your connection times out you dont freeze your UI, then i would use a custom wait timer not the built in one as cross threading can be a pain.
wait timer:
Public Sub Wait(ByVal wait_time As Integer)
Dim time As Date
time = Now.AddMilliseconds(wait_time)
Do While time > Now
Application.DoEvents()
Loop
End Sub
example of threading:
Private services_check As Thread
private sub form1_load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
services_check = new thread(AddressOf 'Current code in a public sub')
services_cheack.IsBackground = True
Services_check.start()
It may not be the most elegant solution but its how i would do it, as for your current code im sorry i dont know enough about remote connections to help you.