Windows Service

Question

Hi,

I'm trying to write a small Windows Service in .NET 3.5, that check every 10mn or so if thee are new files in "C:\demofolder", then send e-mail out. So far, I made it to here like in the following code, then there's error in Public Sub New()

Imports System
Imports System.Timers
Imports System.ServiceProcess
Public Class TestMyService

    '  A timer that controls how frequenty the example writes to the
    '  event log.
    Private serviceTimer As Timer

    Public Sub New()

        '  Set the ServiceBase.ServiceName property.
        ServiceName = "TestMyService Service"

        '  Configure the level of control available on the service.
        CanStop = True
        CanPauseAndContinue = True
        CanHandleSessionChangeEvent = True

        '  Configure the service to log important events to the
        '  Application event log automatically.
        AutoLog = True

    End Sub

    Protected Overrides Sub OnStart(ByVal args() As String)
        ' Add code here to start your service. This method should set things
        ' in motion so your service can do its work.
    End Sub

    Protected Overrides Sub OnStop()
        ' Add code here to perform any tear-down necessary to stop your service.
    End Sub

Public Shared Sub Main()

    '  Create an instance of the TestMyService class that will write
    '  an entry to the Application event log.  Pass the object to the
    '  shared ServiceBase.Run method.
    ServiceBase.Run(New TestMyService)

End Sub


End Class

I got the following error message:

Sub Main' is declared more than once in 'mcWinService.TestMyService': mcWinService.TestMyService.Main(), mcWinService.TestMyService.Main()

Public Shared Sub Main()' has multiple definitions with identical signatures.

Public Sub New()' in designer-generated type 'mcWinService.TestMyService' should call InitializeComponent method.

Answer 1

Sounds like you have another Main method in another of the project files. Do a project wide search for the word Main and see if you can find it.

You can also fix that error by going into the properties dialog for the project and selecting TestMyService as the startup object rather that Sub Main.

Answer 2

Try to move

ServiceBase.Run(New TestMyService) from Public Shared Sub Main()

to

Protected Overrides Sub OnStart

then remove Public Shared Sub Main()

Also, remove Public Sub New(), because you can set those properties from "Property Windows". F7 to toggle from code to designer view.

Update 1: Example of Windows Service for folder monitor

Imports System.Net.Mail
Imports System.Net
Imports System.Timers
Imports System.IO

Public Class DemoFolderMonitor

    Private Shared timer As System.Timers.Timer
    Private Shared timerInterval As Integer

    Protected Overrides Sub OnStart(ByVal args() As String)
        ' Add code here to start your service. This method should set things
        ' in motion so your service can do its work.

        '  Use the EventLog object automatically configured by the
        '  ServiceBase class to write to the event log.
        'EventLog.WriteEntry(String.Format("DemoFolderMonitor Service starting."))

        ' Set the Interval  (1sec = 1000 milliseconds).
        timerInterval = 2000
        timer = New System.Timers.Timer(timerInterval)
        EventLog.WriteEntry("DemoFolderMonitor Service starting.")

        ' Hook up the Elapsed event for the timer.
        AddHandler timer.Elapsed, AddressOf WatchFolder

        timer.Interval = timerInterval
        timer.Enabled = True

    End Sub

    Protected Overrides Sub OnStop()
        ' Add code here to perform any tear-down necessary to stop your service.
        EventLog.WriteEntry("DemoFolderMonitor Service stopping...")

    End Sub

    Protected Sub WatchFolder()

        Dim watcher As New FileSystemWatcher
        watcher.Path = "C:\Demo\"

        watcher.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite Or NotifyFilters.FileName Or NotifyFilters.DirectoryName)

        'watch all file types.
        watcher.Filter = "*.*"
        ' Add event handlers.
        AddHandler watcher.Changed, AddressOf OnChanged
        AddHandler watcher.Created, AddressOf OnChanged
        AddHandler watcher.Deleted, AddressOf OnChanged
        AddHandler watcher.Renamed, AddressOf OnRenamed

        ' Begin watching.
        watcher.EnableRaisingEvents = True

    End Sub

    'Define the event handlers.
    Private Shared Sub OnChanged(ByVal source As Object, ByVal e As FileSystemEventArgs)
        ' Specify what is done when a file is changed, created, or deleted.
        Dim changeLog = "File: " & e.FullPath & " " & " | Action: " & e.ChangeType.ToString
        WriteChangeLog(changeLog)

    End Sub

    Private Shared Sub OnRenamed(ByVal source As Object, ByVal e As RenamedEventArgs)
        ' Specify what is done when a file is renamed.
        Dim changeLog = "File" & e.OldFullPath & " " & "renamed to" & " " & e.FullPath
        WriteChangeLog(changeLog)

    End Sub

    'Custom action. You can either send an e-mail or write change to local file
    'In this example I write change to local file
    Private Shared Sub WriteChangeLog(ByVal changeLog As String)

        'Create a text file and write the change log to the text file
        Dim filename As String = DateTime.Now.ToString("hh-mm-ss") & ".txt"
        Dim writer As StreamWriter
        writer = File.CreateText("C:\ChangeLog\" & filename)
        writer.WriteLine("Datetime Log  at {0} Log Message: {1}", DateTime.Now.ToString("MMM-dd-yyyy @ hh:mm:ss tt"), changeLog)
        writer.Close()

    End Sub

End Class

For further related reading check:

• Setup project for a Windows Service application
• System.Timers Namespace
• FileSystemWatcher Class

Cheer!