Windows Service not looping

[CraigMuckleston]

I have built a windows service that should check whether a page can be returned from a site (from various servers). If not, it logs to the Application Error log. My trouble is this. It runs once, but doesn't seem to loop at all, ie, I only get the 1 round of warning messages (it also sends me a net message, but that will be removed eventually). My code for the whole service is below:

Imports System
Imports System.IO
Imports System.Net
Imports System.Text
Imports System.Net.Dns
Imports System.Threading
Imports System.ServiceProcess
 
Public Class IISPolling
    Inherits System.ServiceProcess.ServiceBase
 
    Private thrPollingThread As New Thread( _
        New ThreadStart(AddressOf PollProcess))
 
    Dim arrServers(2, 1) As String
    Dim x, y As Integer
 
    Const iChunk = 512
    Dim arrRecipients() As String
    Dim strLocalName As String = GetHostName()
    Dim strServerName As String
    Dim strMsg As String
    Dim lngPos As Long = 1
 
#Region " Component Designer generated code "
 
    Public Sub New()
        MyBase.New()
 
        ' This call is required by the Component Designer.
        InitializeComponent()
 
 
    End Sub
 
    'UserService overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub
 
    ' The main entry point for the process
    <MTAThread()> _
    Shared Sub Main()
        Dim ServicesToRun() As System.ServiceProcess.ServiceBase
 
        ServicesToRun = New System.ServiceProcess.ServiceBase() {New IISPolling}
 
        System.ServiceProcess.ServiceBase.Run(ServicesToRun)
    End Sub
 
    'Required by the Component Designer
    Private components As System.ComponentModel.IContainer
 
    ' NOTE: The following procedure is required by the Component Designer
    ' It can be modified using the Component Designer.  
    ' Do not modify it using the code editor.
    Friend WithEvents logEvents As System.Diagnostics.EventLog
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.logEvents = New System.Diagnostics.EventLog
        CType(Me.logEvents, System.ComponentModel.ISupportInitialize).BeginInit()
        '
        'logEvents
        '
        Me.logEvents.EnableRaisingEvents = True
        Me.logEvents.Log = "Application"
        Me.logEvents.Source = "IISPolling"
        '
        'IISPolling
        '
        Me.ServiceName = "IISPolling"
        CType(Me.logEvents, System.ComponentModel.ISupportInitialize).EndInit()
 
    End Sub
 
#End Region
 
    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.
        logEvents.WriteEntry("IIS Polling service started on " & strLocalName & ".")
 
        ' Start the thread.
        thrPollingThread.Start()
    End Sub
 
    Protected Overrides Sub OnStop()
        ' Add code here to perform any tear-down necessary to stop your service.
        logEvents.WriteEntry("IIS Polling service stopped on " & strLocalName & ".")
 
        ' Stop the thread.
        thrPollingThread.Abort()
    End Sub
 
    Private Sub PollProcess()
        Do
            ' Wait...
            Thread.Sleep(30000)
            PollingPass()
        Loop
    End Sub
 
    Private Sub PollingPass()
 
        Dim request As HttpWebRequest
        Dim response As HttpWebResponse
 
        arrServers(0, 0) = "http://server1/DotNetNuke/Default.aspx"
        arrServers(0, 1) = "serverA"
        arrServers(1, 0) = "http://server2/DotNetNuke/Default.aspx"
        arrServers(1, 1) = "serverB"
        arrServers(2, 0)  = "http://server3/DotNetNuke/Default.aspx"
        arrServers(2, 1) = "serverC"
 
        x = 0
        Do Until x > arrServers.Length - 1
 
            strServerName = arrServers(x, 1)
            request = CType(WebRequest.Create(arrServers(x, 0)), HttpWebRequest)
 
            'set some reasonable limits on resources used by this request
            request.MaximumAutomaticRedirections = 4
            request.MaximumResponseHeadersLength = 4
 
            'set credentials to use for this request.
            request.Credentials = CredentialCache.DefaultCredentials
 
            Try
                response = CType(request.GetResponse(), HttpWebResponse)
                'TODO: take this line out otherwise the event log will just fill up
                'logEvents.WriteEntry("IIS running on " & strServerName)
            Catch ex As Exception
                logEvents.WriteEntry("IIS on " & strServerName & " is not responding '" & _
                    ex.Message & "'", EventLogEntryType.Warning)
                logEvents.WriteEntry("IIS service on " & strServerName & " - Stack Trace: " & _
                    ex.StackTrace, EventLogEntryType.Warning)
 
                SendNetMsg("IIS Is Not Responding on server: " & strServerName)    'send a net message
 
            End Try
            x += 1
        Loop
        If Not response Is Nothing Then
            response.Close()
        End If
 
    End Sub
 
    Private Sub SendNetMsg(ByVal msg As String)
 
        arrRecipients(0) = "myPC"
        'arrRecipients(1) = "myPC2"
        y = 0
 
        Do Until lngPos > Len(strMsg)
            Do Until y > arrRecipients.Length - 1
                Dim lretval As Long = Shell("net send " & arrRecipients(y) & _
           " """ & Mid(msg, lngPos, iChunk) & """", vbHide)
 
                lngPos += iChunk
                'pause to stop out of sequence message chunks
                Thread.Sleep(100)
                y += 1
            Loop
        Loop
 
    End Sub
 
End Class

[kenobewan]

My assumption is the exception is caught, sendnetmsg is called and runs only once as y=0 & arrRecipients.Length - 1=0. Therefore y only has to run once to be greater than 0.

Otherwise you will need to do some debugging - I would parse the code down until it is working and build it back up. HTH.