How to use RFC-SDK with FreeBASIC - Part 1: The Connection

[Stefan-Schnell]

FreeBASIC is a powerful free and open source BASIC compiler for Windows and Linux. You find the official site here and the very good German site here. The actual version 0.90.1 can only create 32-bit applications, but the new beta release 0.91 can also create 64-bit applications - look here (in German). FreeBASIC is an ideal partner to SAP NetWeaver RFC SDK, because it is very easy to use SAP NetWeaver RFC SDK with FreeBASIC. This is the reason for this tutorial.

We start with an include file called sapnwrfc.inc. It collects constants, structures and declarations:

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



  '-Includes------------------------------------------------------------

    #Include Once "windows.bi"



  '-Constants-----------------------------------------------------------

    Enum

      RFC_OK = 0

      RFC_RETRY = 14

    End Enum



  '-Structures----------------------------------------------------------

  

    '-RFC_ERROR_INFO----------------------------------------------------

      Type RFC_ERROR_INFO

        code As Integer

        group As Integer

        key As WString * 128

        message As WString * 512

        abapMsgClass As WString * 21

        abapMsgType As WString * 2

        abapMsgNumber As WString * 4

        abapMsgV1 As WString * 51

        abapMsgV2 As WString * 51

        abapMsgV3 As WString * 51

        abapMsgV4 As WString * 51

      End Type



    '-RFC_CONNECTION_PARAMETER------------------------------------------

      Type RFC_CONNECTION_PARAMETER

        name As WString Ptr

        value As WString Ptr

      End Type



  '-Declarations--------------------------------------------------------

    Declare Function RfcCloseConnection StdCall Lib "sapnwrfc" _

      Alias "RfcCloseConnection" (ByVal rfcHandle As Integer, _

      errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcCreateFunction StdCall Lib "sapnwrfc" _

      Alias "RfcCreateFunction" (ByVal funcDescHandle As Integer, _

      errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcCreateFunctionDesc StdCall Lib "sapnwrfc" _

      Alias "RfcCreateFunctionDesc" (name As WString, _

      errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcGetChars StdCall Lib "sapnwrfc" _

      Alias "RfcGetChars" (ByVal dataHandle As Integer, _

      name As WString, ByVal charBuffer As WString Ptr, _

      bufferLength As Integer, errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcGetStructure StdCall Lib "sapnwrfc" _

      Alias "RfcGetStructure" (ByVal dataHandle As Integer, _

      name As WString, ByVal strucHandle As Integer, _

      errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcDestroyFunction StdCall Lib "sapnwrfc" _

      Alias "RfcDestroyFunction" (ByVal funcHandle As Integer, _

      errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcGetFunctionDesc StdCall Lib "sapnwrfc" _

      Alias "RfcGetFunctionDesc" (ByVal rfcHandle As Integer, _

      funcName As WString, errorInfo As RFC_ERROR_INFO) _

      As Integer



    Declare Function RfcGetVersion StdCall Lib "sapnwrfc" _

      Alias "RfcGetVersion" (ByVal MajorVersion As Long Ptr, _

      ByVal MinorVersion As Long Ptr, ByVal PatchLevel As Long Ptr) _

      As WString Ptr



    Declare Function RfcInstallServerFunction StdCall Lib "sapnwrfc" _

      Alias "RfcInstallServerFunction" (sysID As WString, _

      ByVal funcDescHandle As Integer, ByVal serverFunction As Integer, _

      errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcInvoke StdCall Lib "sapnwrfc" _

      Alias "RfcInvoke" (ByVal rfcHandle As Integer, _

      ByVal funcHandle As Integer, errorInfo As RFC_ERROR_INFO) _

      As Integer



    Declare Function RfcListenAndDispatch StdCall Lib "sapnwrfc" _

      Alias "RfcListenAndDispatch" (ByVal rfcHandle As Integer, _

      ByVal timeout As Integer, errorInfo As RFC_ERROR_INFO) _

      As Integer



    Declare Function RfcOpenConnection StdCall Lib "sapnwrfc" _

      Alias "RfcOpenConnection" (ByVal connectionParams As Integer, _

      ByVal paramCount As Integer, errorInfo As RFC_ERROR_INFO) _

      As Integer



    Declare Function RfcPing StdCall Lib "sapnwrfc" _

      Alias "RfcPing" (ByVal rfcHandle As Integer, _

      errorInfo As RFC_ERROR_INFO) As Integer



    Declare Function RfcRegisterServer StdCall Lib "sapnwrfc" _

      Alias "RfcRegisterServer" (ByVal connectionParams As Integer, _

      ByVal paramCount As Integer, errorInfo As RFC_ERROR_INFO) _

      As Integer



  '-Macros--------------------------------------------------------------

    #Macro RfcErrorHandler()

      If RfcErrorInfo.code <> RFC_OK Then

        MessageBox(null, RfcErrorInfo.message, "RFC Error Message", _

          MB_OK Or MB_ICONERROR)

      End If

    #EndMacro



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

Not all functions of the SAP NetWeaver RFC library are declared, only the functions we needed for this tutorial. Store this file, that are all preparations.

 

Now we take a look at our first FreeBASIC program:

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



  '-Includes------------------------------------------------------------

    #Include Once "sapnwrfc.inc"



  '-Variables-----------------------------------------------------------

    Dim RfcErrorInfo As RFC_ERROR_INFO

    Dim connParams(6) AS RFC_CONNECTION_PARAMETER

    Dim hRFC As Integer

    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



      MessageBox(null, "Check connection with TAC SMGW in the " & _

        "SAP system", "", MB_OK Or MB_ICONINFORMATION)



      RfcCloseConnection hRFC, RfcErrorInfo

      RfcErrorHandler()



    End If



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

 

It is very easy. In the first block we define the connection parameter and then we open a connection to our SAP system via the function RFCOpenConnection. The program stops with a message box and in our SAP system we find, with the TAC SMGW, our connected client application.

 



 

After closing the message box we close the connection via the function RFCCloseConnection.

As you can see, it is very easy to code a client application which connects an SAP system.

You find Part 2 here, and Part 3 here.