Problem using FileSystemWatcher

[bahruddina]

Hi all,

I'm using FileSystemWatcher to monitor folder for changes( new file added). This application is developed as a Windows Services.

The problem is - sometimes it cannot detect the changes that occurred on the folder (new file added).

Is there any tips that I can use to solve this problem...PLEASE ?

Below are the codes from my application:


declarations:

#Region " Private Variables "

    Private m_objLog As EventLog
    Private m_objWatcher As IO.FileSystemWatcher

    Dim gFTPDirectory As String
    Dim gFTPFilePrefix As String
    Dim gQTFSPath As String

    Dim gobjTProcessStart As New System.Threading.ThreadStart(AddressOf ProcessFilesAtStartUp)
    Dim gobjTProcess As New System.Threading.Thread(gobjTProcessStart)

#End Region

When service is started:

Protected Overrides Sub OnStart(ByVal args() As String)

        Try

            'initialize new event log
            m_objLog = New EventLog()
            'check if log already exists
            If Not m_objLog.SourceExists("ExaQFile2QTFS") Then
                m_objLog.CreateEventSource("ExaQFile2QTFS", "Application")
            End If
            m_objLog.Source = "ExaQFile2QTFS"

            'read the setting and get the tag list
            ReadINIFile()

            'initialize Watcher
            m_objWatcher = New IO.FileSystemWatcher()

            'Set Path to Watch
            m_objWatcher.Path = gFTPDirectory
            'Set Filter to *.*
            m_objWatcher.Filter = gFTPFilePrefix & "*.txt"
            'Watch Subdirectories
            m_objWatcher.IncludeSubdirectories = False
            'Set Changes to be watched
            m_objWatcher.NotifyFilter = IO.NotifyFilters.FileName

            'Pointer on Sub for events
            AddHandler m_objWatcher.Created, AddressOf Changed

            'Start Watching
            m_objWatcher.EnableRaisingEvents = True

            'prepare for system start up...thread
            gobjTProcess.IsBackground = True
            gobjTProcess.Start()

        Catch e As Exception
            m_objLog.WriteEntry("[ Message= " & e.Message & ":: Source= " & e.Source & " ] at OnStart", EventLogEntryType.Error)
        Finally

        End Try

    End Sub

code when folder changed:

#Region " Subs for Delegate "
    Private Sub Changed(ByVal sender As Object, ByVal e As System.IO.FileSystemEventArgs)
        Try

            ProcessFiles()

        Catch ex As Exception
            m_objLog.WriteEntry("[ Message= " & ex.Message & ":: Source= " & ex.Source & " ] at Changed", EventLogEntryType.Error)
        Finally

        End Try
    End Sub
#End Region

when service is stoped:

Protected Overrides Sub OnStop()

        Try
            m_objLog.Dispose()
            m_objWatcher.Dispose()
        Catch e As Exception
            m_objLog.WriteEntry("[ Message= " & e.Message & ":: Source= " & e.Source & " ] at OnStop", EventLogEntryType.Error)
        End Try

    End Sub

Please feel free to see my code.......

Thank you very very much in advance for the kindness help and tips.

Regards.

[Pirate]

See if this can help you .
http://abstractvb.com/code.asp?A=1081

[bahruddina]

thanx for the info.

I've try using thread in Changed procedure:

#Region " Subs for Delegate "
    Private Sub Changed(ByVal sender As Object, ByVal e As System.IO.FileSystemEventArgs)
        Try

            Dim a As New System.Threading.ThreadStart(AddressOf ProcessFile)
        Dim b As New System.Threading.Thread(a)
        b.Start()

        Catch ex As Exception
            m_objLog.WriteEntry("[ Message= " & ex.Message & ":: Source= " & ex.Source & " ] at Changed", EventLogEntryType.Error)
        Finally

        End Try
    End Sub
#End Region

more stable than before.

But I have one more problem:

I want to be notified only when the file copy/transfer completed. Currently my code will notify whenever the folder added with new file - even if the file copy/transfer process not yet completed !

Is there any solution to solve this problem ?

thanx in advance.

regards.

[PDFpilot]

We have the same issue in our project. We are watching for new files using the filesystemwatcher however the file can take up to 1 minute to finish writing. The service does not process these files as a result. We have had to resort to writing the files (PDF) to a staging folder and then moving them into the watched folder. This is not ideal - we would like to eliminate this workaround. Any suggestions ?

[bahruddina]

Please refer to below:
http://www.vbforums.com/showthread.php?t=273285

[jmcilhinney]

I believe you'll find that if you create a FileInfo object and test the Attributes property. If it includes the Offline attribute then the file has not finished being created and you should not try to open it. You can use a loop and repeatedly test until the Offline attribute is not found. I'm not 100% sure but I think this will work, and if so it will avoid throwing and handling exceptions, which should always be avoided if possible.