How To Use COM Functions in PowerShell Easily, in Comparison with VBScript, Using the Example of CCo

Over two years ago I presented COM Connector (CCo) here – CCo makes the using of the NetWeaver RFC library very easy.

Slowly but surely the landscape of the script language environments changed in Windows OS – from Windows Script Host (WSH) to PowerShell. From this point of view it seems good to take also a movement.

Here a PowerShell example how to get all installed SAP components and its version numbers in comparison with a VBScript which offers the same information.

#-Begin-----------------------------------------------------------------

  #-Constants-----------------------------------------------------------
    $RFC_OK = 0
    $VarByRef = -1

  #-Includes------------------------------------------------------------
    ."Includes\COM.ps1"

  #-Function Get-SAPComponents------------------------------------------
    Function Get-SAPComponents {

      $SAP = $null
      $SAP = Create-Object "COMNWRFC"
      if ($SAP -eq $null) {
        Break
      }

      $hRFC = Invoke-Method $SAP "RfcOpenConnection" @(
        "ASHOST=NSP, SYSNR=00, CLIENT=001, USER=BCUSER")
      if ($hRFC -eq 0) {
        Free-Object $SAP
        Break
      }

      $hFuncDesc = Invoke-Method $SAP "RfcGetFunctionDesc" @(
        $hRFC, "DELIVERY_GET_INSTALLED_COMPS")
      if ($hFuncDesc -eq 0) {
        $rc = Invoke-Method $SAP "RfcCloseConnection" $hRFC
        Free-Object $SAP
        Break
      }

      $hFunc = Invoke-Method $SAP "RfcCreateFunction" $hFuncDesc
      if ($hFunc -eq 0) {
        $rc = Invoke-Method $SAP "RfcCloseConnection" $hRFC
        Free-Object $SAP
        Break
      }

      $rc = Invoke-Method $SAP "RfcInvoke" @($hRFC, $hFunc)
      if ($rc -eq $RFC_OK) {

        $rc = Invoke-Method $SAP "RfcGetTable" @(
          $hFunc, "TT_COMPTAB", $VarByRef)
        if ($rc -eq $RFC_OK) {

          $hTable = Get-Property $SAP "lngByRef"
          $rc = Invoke-Method $SAP "RfcGetRowCount" @(
            $hTable, $VarByRef)
          $RowCount = Get-Property $SAP "lngByRef"

          $rc = Invoke-Method $SAP "RfcMoveToFirstRow" $hTable

          for ($i = 1; $i -le $RowCount ; $i++) {

            $Row = Invoke-Method $SAP "RfcGetCurrentRow" $hTable

            $rc = Invoke-Method $SAP "RfcGetChars" @(
              $Row, "COMPONENT", $VarByRef, 30)
            $charBuffer = Get-Property $SAP "strByRef"
            $txt = $txt + $charBuffer

            $rc = Invoke-Method $SAP "RfcGetChars" @(
              $Row, "RELEASE", $VarByRef, 10)
            $charBuffer = Get-Property $SAP "strByRef"
            $txt = $txt + $charBuffer

            $rc = Invoke-Method $SAP "RfcGetChars" @(
              $Row, "EXTRELEASE", $VarByRef, 10)
            $charBuffer = Get-Property $SAP "strByRef"
            $txt = $txt + $charBuffer

            $rc = Invoke-Method $SAP "RfcGetChars" @(
              $Row, "COMP_TYPE", $VarByRef, 1)
            $charBuffer = Get-Property $SAP "strByRef"
            $txt = $txt + $charBuffer + "`r`n"

            if ($i -lt $RowCount) {
              $rc = Invoke-Method $SAP "RfcMoveToNextRow" $hTable
            }

          }
        }
      }

      $rc = Invoke-Method $SAP "RfcDestroyFunction" $hFunc
      $rc = Invoke-Method $SAP "RfcCloseConnection" $hRFC
      Free-Object $SAP
      Remove-Variable SAP
      $txt
    }

  #-Function Main-------------------------------------------------------
    Function Main {
      $Components = Get-SAPComponents
      Write-Host $Components
    }

  #-Main----------------------------------------------------------------
    Main

#-End-------------------------------------------------------------------

Here now the VBScript:

'-Begin-----------------------------------------------------------------

  '-Directives----------------------------------------------------------
    Option Explicit

  '-Constants-----------------------------------------------------------
    Const RFC_OK = 0

  '-Function GetSAPComponents-------------------------------------------
    Function GetSAPComponents()

      '-Variables-------------------------------------------------------
        Dim SAP, hRFC, rc, hFuncDesc, hFunc, hTable, RowCount, i, Row
        Dim charBuffer, strText

      Set SAP = CreateObject("COMNWRFC")
      If Not IsObject(SAP) Then
        Exit Function
      End If

      hRFC = SAP.RfcOpenConnection("ASHOST=NSP, SYSNR=00, " & _
        "CLIENT=001, USER=BCUSER")
      If hRFC = 0 Then
        Set SAP = Nothing
        Exit Function
      End If

      hFuncDesc = SAP.RfcGetFunctionDesc(hRFC, _
        "DELIVERY_GET_INSTALLED_COMPS")
      If hFuncDesc = 0 Then
        rc = SAP.RfcCloseConnection(hRFC)
        Set SAP = Nothing
        Exit Function
      End If

      hFunc = SAP.RfcCreateFunction(hFuncDesc)

      If hFunc = 0 Then
        rc = SAP.RfcCloseConnection(hRFC)
        Set SAP = Nothing
        Exit Function
      End If

      If SAP.RfcInvoke(hRFC, hFunc) = RFC_OK Then
        If SAP.RfcGetTable(hFunc, "TT_COMPTAB", hTable) = RFC_OK Then
          rc = SAP.RfcGetRowCount(hTable, RowCount)
          rc = SAP.RfcMoveToFirstRow(hTable)
          For i = 1 To RowCount
            Row = SAP.RfcGetCurrentRow(hTable)
            rc = SAP.RfcGetChars(Row, "COMPONENT", charBuffer, 30)
            strText = strText & Trim(charBuffer) & " "
            rc = SAP.RfcGetChars(Row, "RELEASE", charBuffer, 10)
            strText = strText & Trim(charBuffer) & " "
            rc = SAP.RfcGetChars(Row, "EXTRELEASE", charBuffer, 10)
            strText = strText & Trim(charBuffer) & " "
            rc = SAP.RfcGetChars(Row, "COMP_TYPE", charBuffer, 1)
            strText = strText & Trim(charBuffer) & vbCrLf
            If i < RowCount Then
              rc = SAP.RfcMoveToNextRow(hTable)
            End If
          Next
        End If
      End If

      rc = SAP.RfcDestroyFunction(hFunc)
      rc = SAP.RfcCloseConnection(hRFC)
      Set SAP = Nothing

      GetSAPComponents = strText
    End Function

  '-Sub Main------------------------------------------------------------
    Sub Main()
      MsgBox GetSAPComponents()
    End Sub

  '-Main----------------------------------------------------------------
    Main

'-End-------------------------------------------------------------------

As you can see it is very comparable.

To establish the comparibility I use an include file, which stores the COM access routines like Create-Object, Invoke-Method etc.

#-Begin-----------------------------------------------------------------

  #-Load assembly-------------------------------------------------------
  [Reflection.Assembly]::LoadWithPartialName("Microsoft.VisualBasic") > $Null
  [Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") > $Null

  #-Function Create-Object----------------------------------------------
  Function Create-Object([String]$objectName) {
    try {
      New-Object -ComObject $objectName
    }
    catch {
      [Void] [System.Windows.Forms.MessageBox]::Show(
        "Can't create object", "Important hint", 0)
    }  
  }

  #-Function Get-Object-------------------------------------------------
  Function Get-Object([String]$pathName, [String]$class) {
    [Microsoft.VisualBasic.Interaction]::GetObject($pathName, $class)
  }

  #-Sub Free-Object-----------------------------------------------------
  Function Free-Object([__ComObject]$object) {
    [Void] [System.Runtime.Interopservices.Marshal]::ReleaseComObject($object)
  }

  #-Function Get-Property-----------------------------------------------
  Function Get-Property([__ComObject]$object, [String]$propertyName,
    $propertyParameters) {
    $objectType = [System.Type]::GetType($object)
    $objectType.InvokeMember($propertyName,
      [System.Reflection.Bindingflags]::GetProperty,
      $null, $object, $propertyParameters)
  }

  #-Sub Set-Property----------------------------------------------------
  Function Set-Property([__ComObject]$object, [String]$propertyName, 
  	$propertyValue) {
    $objectType = [System.Type]::GetType($object)
    [Void] $objectType.InvokeMember($propertyName,
      [System.Reflection.Bindingflags]::SetProperty,
      $null, $object, $propertyValue)
  }

  #-Function Invoke-Method----------------------------------------------
  Function Invoke-Method([__ComObject]$object, [String]$methodName, 
  	$methodParameters) {
    $objectType = [System.Type]::GetType($object)
    $output = $objectType.InvokeMember($methodName,
      "InvokeMethod", $NULL, $object, $methodParameters)
    if ( $output ) { $output }
  }

#-End-------------------------------------------------------------------

With this tiny include you can use COM functions in PowerShell almost like in VBScript.

Let the games begin.

2016/03/08:
Minor changes for PowerShell 5 compatibility.