Windows Service, Using timer, VB.net

Hi everyone. I am kind of newbie when it comes to writing windows services but I'm pretty sure the problem I'm experiencing is not just a mistake in understanding.
I had set up a windows service and had it working, firing off a timer every 60 seconds and writing an entry into my EventLog. It appears as if the minute I place any other code into it and I mean any other code, the timer stops working and won't even write the log entry.

I would think if it were a problem with some piece of the code following it; that it would at least write that line and then error.

Anyway Here is what I'm doing. I'm hoping maybe someone who has gone through this could give me a little direction to kick start the issue. Thanks in advance.

Code:

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Imports System.Runtime.InteropServices
Imports WinSCP
Imports System.Threading

Public Class MyNewService
    Public eventID As Integer
    Declare Auto Function SetServiceStatus Lib "advapi32.dll" (ByVal handle As IntPtr, ByRef serviceStatus As ServiceStatus) As Boolean
    Public Sub New()
        MyBase.New()

        ' This call is required by the designer.
        InitializeComponent()
        Try
            ' Add any initialization after the InitializeComponent() call.
            Me.EventLog1 = New System.Diagnostics.EventLog
            If Not System.Diagnostics.EventLog.SourceExists("MyNewService") Then
                System.Diagnostics.EventLog.CreateEventSource("MyNewService", "MyNewLog")
            End If
            EventLog1.Source = "MyNewService"
            EventLog1.Log = "MyNewLog"
        Catch err As System.Diagnostics.Eventing.Reader.EventLogException
            MsgBox(err.InnerException)
        End Try
    End Sub

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

        Dim serviceStatus As ServiceStatus = New ServiceStatus()
        serviceStatus.dwCurrentState = ServiceState.SERVICE_START_PENDING
        serviceStatus.dwWaitHint = 100000
        SetServiceStatus(Me.ServiceHandle, serviceStatus)

        serviceStatus.dwCurrentState = ServiceState.SERVICE_RUNNING
        SetServiceStatus(Me.ServiceHandle, serviceStatus)

        ' Add code here to start your service. This method should set things
        ' in motion so your service can do its work.
        EventLog1.WriteEntry("Service Started")
       
        Dim timer As System.Timers.Timer = New System.Timers.Timer()
        timer.Enabled = True
        timer.Interval = 60000
        AddHandler timer.Elapsed, AddressOf Me.OnTimer
        timer.Start()
    End Sub

    Private Sub OnTimer(sender As Object, e As Timers.ElapsedEventArgs)
        ' TODO: Insert Monitoring Activies Here.
        Try
            EventLog1.WriteEntry("Checking For New Files", EventLogEntryType.Information, eventID)


            ' Setup session options
            Dim sessionOptions As New SessionOptions
            EventLog1.WriteEntry("SessionOptions", EventLogEntryType.Information, eventID)
            With sessionOptions
                .Protocol = Protocol.Sftp
                .HostName = "XXXXXXXXXXX"
                .UserName = "XXXXXXXXXXX"
                .Password = "XXXXXXXXXXX"
                .SshHostKeyFingerprint = "XXXXXXXXXXXXXXXX"
            End With

            Using session As New Session
                ' Connect
                session.Open(sessionOptions)
                EventLog1.WriteEntry("Session To Cheyney FTP Open")

                ' Download files
                Dim transferOptions As New TransferOptions
                transferOptions.TransferMode = TransferMode.Binary

                Dim transferResult As TransferOperationResult
                transferResult = session.GetFiles("/Inbox1/*", "C:\Localfolder\", False, transferOptions)

                ' Throw on any error
                transferResult.Check()

                ' Print results
                For Each transfer In transferResult.Transfers
                    EventLog1.WriteEntry(".....Transferring File:" & transfer.filename)
                Next
            End Using



        Catch err As Exception
            EventLog1.WriteEntry("Service Exception: " & err.InnerException.ToString)


        End Try



        eventID = eventID + 1
    End Sub

    Protected Overrides Sub OnStop()
        Dim serviceStatus As ServiceStatus = New ServiceStatus()
        serviceStatus.dwCurrentState = ServiceState.SERVICE_STOPPED
        SetServiceStatus(Me.ServiceHandle, serviceStatus)
        ' Add code here to perform any tear-down necessary to stop your service.
        EventLog1.WriteEntry("Service Stopped")
    End Sub


    Public Enum ServiceState
        SERVICE_STOPPED = 1
        SERVICE_START_PENDING = 2
        SERVICE_STOP_PENDING = 3
        SERVICE_RUNNING = 4
        SERVICE_CONTINUE_PENDING = 5
        SERVICE_PAUSE_PENDING = 6
        SERVICE_PAUSED = 7
    End Enum

    <StructLayout(LayoutKind.Sequential)>
    Public Structure ServiceStatus
        Public dwServiceType As Long
        Public dwCurrentState As ServiceState
        Public dwControlsAccepted As Long
        Public dwWin32ExitCode As Long
        Public dwServiceSpecificExitCode As Long
        Public dwCheckPoint As Long
        Public dwWaitHint As Long
    End Structure

End Class

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For future reference, please us appropriate formatting tags when posting code snippets.

vb.net Code:

Imports System.Runtime.InteropServices
Imports WinSCP
Imports System.Threading
 
Public Class MyNewService
    Public eventID As Integer
    Declare Auto Function SetServiceStatus Lib "advapi32.dll" (ByVal handle As IntPtr, ByRef serviceStatus As ServiceStatus) As Boolean
    Public Sub New()
        MyBase.New()
 
        ' This call is required by the designer.
        InitializeComponent()
        Try
            ' Add any initialization after the InitializeComponent() call.
            Me.EventLog1 = New System.Diagnostics.EventLog
            If Not System.Diagnostics.EventLog.SourceExists("MyNewService") Then
                System.Diagnostics.EventLog.CreateEventSource("MyNewService", "MyNewLog")
            End If
            EventLog1.Source = "MyNewService"
            EventLog1.Log = "MyNewLog"
        Catch err As System.Diagnostics.Eventing.Reader.EventLogException
            MsgBox(err.InnerException)
        End Try
    End Sub
 
    Protected Overrides Sub OnStart(ByVal args() As String)
 
        Dim serviceStatus As ServiceStatus = New ServiceStatus()
        serviceStatus.dwCurrentState = ServiceState.SERVICE_START_PENDING
        serviceStatus.dwWaitHint = 100000
        SetServiceStatus(Me.ServiceHandle, serviceStatus)
 
        serviceStatus.dwCurrentState = ServiceState.SERVICE_RUNNING
        SetServiceStatus(Me.ServiceHandle, serviceStatus)
 
        ' Add code here to start your service. This method should set things
        ' in motion so your service can do its work.
        EventLog1.WriteEntry("Service Started")
        
        Dim timer As System.Timers.Timer = New System.Timers.Timer()
        timer.Enabled = True
        timer.Interval = 60000
        AddHandler timer.Elapsed, AddressOf Me.OnTimer
        timer.Start()
    End Sub
 
    Private Sub OnTimer(sender As Object, e As Timers.ElapsedEventArgs)
        ' TODO: Insert Monitoring Activies Here.
        Try
            EventLog1.WriteEntry("Checking For New Files", EventLogEntryType.Information, eventID)
 
 
            ' Setup session options
            Dim sessionOptions As New SessionOptions
            EventLog1.WriteEntry("SessionOptions", EventLogEntryType.Information, eventID)
            With sessionOptions
                .Protocol = Protocol.Sftp
                .HostName = "XXXXXXXXXXX"
                .UserName = "XXXXXXXXXXX"
                .Password = "XXXXXXXXXXX"
                .SshHostKeyFingerprint = "XXXXXXXXXXXXXXXX"
            End With
 
            Using session As New Session
                ' Connect
                session.Open(sessionOptions)
                EventLog1.WriteEntry("Session To Cheyney FTP Open")
 
                ' Download files
                Dim transferOptions As New TransferOptions
                transferOptions.TransferMode = TransferMode.Binary
 
                Dim transferResult As TransferOperationResult
                transferResult = session.GetFiles("/Inbox1/*", "C:\Localfolder\", False, transferOptions)
 
                ' Throw on any error
                transferResult.Check()
 
                ' Print results
                For Each transfer In transferResult.Transfers
                    EventLog1.WriteEntry(".....Transferring File:" & transfer.filename)
                Next
            End Using
 
 
 
        Catch err As Exception
            EventLog1.WriteEntry("Service Exception: " & err.InnerException.ToString)
 
 
        End Try
 
 
 
        eventID = eventID + 1
    End Sub
 
    Protected Overrides Sub OnStop()
        Dim serviceStatus As ServiceStatus = New ServiceStatus()
        serviceStatus.dwCurrentState = ServiceState.SERVICE_STOPPED
        SetServiceStatus(Me.ServiceHandle, serviceStatus)
        ' Add code here to perform any tear-down necessary to stop your service.
        EventLog1.WriteEntry("Service Stopped")
    End Sub
 
 
    Public Enum ServiceState
        SERVICE_STOPPED = 1
        SERVICE_START_PENDING = 2
        SERVICE_STOP_PENDING = 3
        SERVICE_RUNNING = 4
        SERVICE_CONTINUE_PENDING = 5
        SERVICE_PAUSE_PENDING = 6
        SERVICE_PAUSED = 7
    End Enum
 
    <StructLayout(LayoutKind.Sequential)>
    Public Structure ServiceStatus
        Public dwServiceType As Long
        Public dwCurrentState As ServiceState
        Public dwControlsAccepted As Long
        Public dwWin32ExitCode As Long
        Public dwServiceSpecificExitCode As Long
        Public dwCheckPoint As Long
        Public dwWaitHint As Long
    End Structure
 
End Class

I edited the post to add [CODE][/CODE] tags, which you can do by pressing the # button and pasting the code between the resulting tags. The other type of formatting, which JMC showed, results from the VB button (which looks like VE on most browsers). I find the CODE tags a bit easier, and that code copies and pastes a bit more easily, but doesn't look as nice in the post.

As to the question: Where do you add this code that causes the problem? I suppose I'd also ask what that code would be, but from the way you asked the question, I assume it could be a wide variety of anything. Perhaps an example may be useful, but I think the location might be the most important part.

Here's a guess, this is a bit subtle.

When you create the timer, you store it in a variable that is local to OnStart(). When OnStart() ends, that variable doesn't exist anymore, so nothing references the Timer. That means the next time the Garbage Collector runs, it can decide to destroy the Timer.

If you want something to live as long as your Service, it should be a field of a class that stays in memory. There's a few ways to go about it, the easiest would be to make the Timer a Shared field of your MyNewService class.

Still doesn't work. IF there is an exception occurring when the first object is defined WHY doesn't the try..catch... grab an error. Since it doesn't I can only assume there wasn't one!

There's a couple of reasons an exception could be being thrown but not displayed to you.

First, you're only catching one kind of exception. If any other kind of exception is being thrown, you don't handle that one.

Second, services can't display UI by default, so even if it's the exception you expect the MsgBox() call might be ignored.

Replace it with something that catches any exception andwrites the exception to a file, generally you can do that without issue. Something like:

Code:

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Catch ex As Exception
    Dim desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
    Dim filePath = Path.Combine(desktopPath, "serviceLog.txt")
    File.WriteAllText(filePath, ex.ToString())
End Try

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