How to use RFC-SDK with FreeBASIC – Part 2: Client Apps (FreeBASIC uses SAP)

In the 2nd part now a few examples of SAP NetWeaver client applications.

We start with a simple ping, to demonstrate how to call an ABAP function module from FreeBASIC.

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

  '-Includes------------------------------------------------------------
    #Include Once "sapnwrfc.inc"

  '-Variables-----------------------------------------------------------
    Dim RfcErrorInfo As RFC_ERROR_INFO
    Dim connParams(6) AS RFC_CONNECTION_PARAMETER
    Dim As Integer hRFC, hFuncDesc, hFunc
    Dim As WString * 16 nASHost, nSysNr, nClient, nUser, nPassWd, nLang
    Dim As WString * 16 vASHost, vSysNr, vClient, vUser, vPassWd, vLang

  '-Main----------------------------------------------------------------
    nASHost = "ASHOST" : vASHost = "ABAP"
    nSysNr  = "SYSNR"  : vSysNr  = "00"
    nClient = "CLIENT" : vClient = "001"
    nUser   = "USER"   : vUser   = "BCUSER"
    nPassWd = "PASSWD" : vPassWd = "minisap"
    nLang   = "LANG"   : vLang   = "EN"

    connParams(0).name = @nASHost : connParams(0).value = @vASHost
    connParams(1).name = @nSysNr  : connParams(1).value = @vSysNr
    connParams(2).name = @nClient : connParams(2).value = @vClient
    connParams(3).name = @nUser   : connParams(3).value = @vUser
    connParams(4).name = @nPassWd : connParams(4).value = @vPassWd
    connParams(5).name = @nLang   : connParams(5).value = @vLang

    hRFC = RfcOpenConnection(@connParams(0), 6, RfcErrorInfo)
    RfcErrorHandler()
    If hRFC <> 0 And RfcErrorInfo.code = RFC_OK Then

      '-Variant 1-------------------------------------------------------
      '-
      '- Do not use lowercase characters in FM name,
      '- use only uppercase characters
      '-
      '-----------------------------------------------------------------
        hFuncDesc = RfcGetFunctionDesc(hRFC, "RFC_PING", RfcErrorInfo)
        RfcErrorHandler()
        If hFuncDesc <> 0 And RfcErrorInfo.code = RFC_OK Then
          hFunc = RfcCreateFunction(hFuncDesc, RfcErrorInfo)
          RfcErrorHandler()
          If hFunc <> 0 And RfcErrorInfo.code = RFC_OK Then
            RfcInvoke hRFC, hFunc, RfcErrorInfo
            RfcErrorHandler()

            If RfcErrorInfo.code = RFC_OK Then
              MessageBox(null, "Ping successful", "FM RFC_PING", _
                MB_OK Or MB_ICONINFORMATION)
            End If

            RfcDestroyFunction hFunc, RfcErrorInfo
            RfcErrorHandler()

          End If
        End If

      '-Variant 2-------------------------------------------------------
        RfcPing hRFC, RfcErrorInfo
        RfcErrorHandler()

        If RfcErrorInfo.code = RFC_OK Then
          MessageBox(null, "Ping successful", "Function RfcPing", _
            MB_OK Or MB_ICONINFORMATION)
        End If

      RfcCloseConnection hRFC, RfcErrorInfo
      RfcErrorHandler()

    End If

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

We open the connection and get a function description from the function module RFC_PING via RfcGetFunctionDesc. With this function description we create the function via RfcCreateFunction in the context of our program and execute it with RfcInvoke. If RfcInvoke is successful we get a message box. Last but not least we destroy the function with RfcDestroyFunction.

The 2nd variant is only an example how to use the function RfcPing from the SAP NetWeaver RFC library.

Our next example is the using of the function module RFC_SYSTEM_INFO. We use the same way as above, but after the invoke we read the result

of the function module. The result is in the structure RFCSI_EXPORT, we get it with RfcGetStructure and the entries with RfcGetChars.

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

  '-Includes------------------------------------------------------------
    #Include Once "sapnwrfc.inc"

  '-Variables-----------------------------------------------------------
    Dim RfcErrorInfo As RFC_ERROR_INFO
    Dim connParams(8) AS RFC_CONNECTION_PARAMETER
    Dim As Integer hRFC, hFuncDesc, hFunc, hStruct
    Dim As WString * 16 nASHost, nSysNr, nClient, nUser, nPassWd, _
      nLang, nUseSAPGUI, nTrace
    Dim As WString * 16 vASHost, vSysNr, vClient, vUser, vPassWd, _
      vLang, vUseSAPGUI, vTrace
    Dim As WString * 9 SAPHost, SAPSysID 
    Dim As WString * 11 SAPDBSys
    Dim As WString * 33 SAPDBHost

  '-Main----------------------------------------------------------------
    nASHost    = "ASHOST"     : vASHost    = "ABAP"
    nSysNr     = "SYSNR"      : vSysNr     = "00"
    nClient    = "CLIENT"     : vClient    = "001"
    nUser      = "USER"       : vUser      = "BCUSER"
    nPassWd    = "PASSWD"     : vPassWd    = "minisap"
    nLang      = "LANG"       : vLang      = "EN"
    nUseSAPGUI = "USE_SAPGUI" : vUseSAPGUI = "0"
    nTrace     = "TRACE"      : vTrace     = "0"

    connParams(0).name = @nASHost    : connParams(0).value = @vASHost
    connParams(1).name = @nSysNr     : connParams(1).value = @vSysNr
    connParams(2).name = @nClient    : connParams(2).value = @vClient
    connParams(3).name = @nUser      : connParams(3).value = @vUser
    connParams(4).name = @nPassWd    : connParams(4).value = @vPassWd
    connParams(5).name = @nLang      : connParams(5).value = @vLang
    connParams(6).name = @nUseSAPGUI : connParams(6).value = @vUseSAPGUI
    connParams(7).name = @nTrace     : connParams(7).value = @vTrace

    hRFC = RfcOpenConnection(@connParams(0), 8, RfcErrorInfo)
    RfcErrorHandler()

    If hRFC <> 0 And RfcErrorInfo.code = RFC_OK Then

      hFuncDesc = RfcGetFunctionDesc(hRFC, "RFC_SYSTEM_INFO", _
        RfcErrorInfo)
      RfcErrorHandler()

      If hFuncDesc <> 0 And RfcErrorInfo.code = RFC_OK Then

        hFunc = RfcCreateFunction(hFuncDesc, RfcErrorInfo)
        RfcErrorHandler()

        If hFunc <> 0 And RfcErrorInfo.code = RFC_OK Then

          RfcInvoke hRFC, hFunc, RfcErrorInfo
          RfcErrorHandler()

          If RfcErrorInfo.code = RFC_OK Then

            RfcGetStructure hFunc, "RFCSI_EXPORT", @hStruct, _
              RfcErrorInfo
            RfcErrorHandler()

            If RfcErrorInfo.code = RFC_OK Then

              RfcGetChars hStruct, "RFCHOST", @SAPHost, 8, _
                RfcErrorInfo
              RfcGetChars hStruct, "RFCSYSID", @SAPSysID, 8, _
                RfcErrorInfo
              RfcGetChars hStruct, "RFCDBHOST", @SAPDBHost, 32, _
                RfcErrorInfo
              RfcGetChars hStruct, "RFCDBSYS", @SAPDBSys, 10, _
                RfcErrorInfo

              MessageBox(null, "Host: " & SAPHost & Chr(13,10) & _
                "SysID: " & SAPSysID & Chr(13,10) & _
                "DBHost: " & SAPDBHost & Chr(13,10) & _
                "DBSys: " & SAPDBSys, "FM RFC_SYSTEM_INFO", _
                MB_OK Or MB_ICONINFORMATION)
              
            End If  
            
          End If

          RfcDestroyFunction hFunc, RfcErrorInfo
          RfcErrorHandler()

        End If

      End If

      RfcCloseConnection hRFC, RfcErrorInfo
      RfcErrorHandler()

    End If

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

The result is displayed in a message box.

As you can see, it is very easy to code a client application which uses function modules from an SAP system.

You find Part 1 here, and Part 3 here.