How to code a small SAP server with PureBasic (Windows)

[Stefan Schnell]

A longer time ago I wrote the topic How to connect a SAP system with PureBasic (Windows). Here is an actual example to code a SAP server program with PureBasic.

How to code a small SAP server with PureBasic (Windows)

To communicate and connect to a SAP system, it offers a few interfaces. One of these is the Remote Function Call (RFC) interface. To get RFC access it is necessary to use the SAP RFC SDK with its libraries. There are two versions of the SDK, the older classic version and the actual NetWeaver version. For the classic version you find a lot of examples, but for the NetWeaver version examples are very rare. In the following article I describe one easy example. It is how to code a small – maybe the smallest – SAP server program. I use the actual version of the SAP NetWeaver RFC SDK.

The idea behind this article is to code the smallest SAP server program in the whole wide world. So I reduce the code to an absolute minimum, but this is the first important step to understand how easy it is to work with SAP NetWeaver RFC SDK.

Preparation
Download the SAP NetWeaver RFC SDK from the SAP marketplace – a passport is required. Also download SAPCAR, the SAP archiver, to unpack the files, because the RFC SDK is packed in SAR format – SAP archive. You need six shared libraries, also known as DLLs, from the package:

• icudt34.dll,
• icuin34.dll,
• icuuc34.dll,
• libicudecnumber.dll,
• libsapucum.dll and
• sapnwrfc.dll.

Copy them to a separate directory. It is necessary to install the Microsoft Visual C runtime modules, you need the runtime library 2005. These are all preparations, now we take a look at the code.

Easy and Small
The following code is very easy to understand. We need only four functions from the SAP NetWeaver RFC SDK

• RfcCreateFunctionDesc,
• RfcInstallServerFunction,
• RfcRegisterServer and
• RfcListenAndDispatch.

With the function RfcCreateFunctionDesc we create a description of a function which can be called from ABAP. With the function RfcInstallServerFunction we install this description on the server and with RfcRegisterServer we register the server – that's all. Last but not least we use RfcListenAndDispatch in an endless loop and each call of the procedure ABAPCall, from an ABAP program, executes this procedure.
The PureBasic program is a console program. Call it from the console with the arguments /g for the gateway host and /x for the gateway service. It shows the connection arguments after the start. Here is the commented source with less than 100 lines:

Code: Select all

; Begin-----------------------------------------------------------------

  ; Constants-----------------------------------------------------------
    Enumeration
      #RFC_OK
      #RFC_RETRY = 14
    EndEnumeration

  ; Structures----------------------------------------------------------
    Structure RFC_ERROR_INFO
      code.i
      group.i
      key.s{128}
      message.s{512}
      abapMsgClass.s{21}
      abapMsgType.s{2}
      abapMsgNumber.s{4}
      abapMsgV1.s{51}
      abapMsgV2.s{51}
      abapMsgV3.s{51}
      abapMsgV4.s{51}
    EndStructure

    Structure RFC_CONNECTION_PARAMETER
      name.i
      value.i
    EndStructure
    
  ; Variables-----------------------------------------------------------
    Global RfcErrorInfo.RFC_ERROR_INFO
    Global hDesc.i = 0, hConn.i = 0, rc, i
    Global GatewayHost.s = #NULL$
    Global GatewayService.s = #NULL$
    Dim connParams.RFC_CONNECTION_PARAMETER(3)

  ; Procedure ABAPCall--------------------------------------------------
    Procedure.i ABAPCall(rfcHandle.i, funcHandle.i, *errorInfo)
      PrintN("ABAPCall received")
      ProcedureReturn #RFC_OK
    EndProcedure

  ; Main----------------------------------------------------------------
    If OpenLibrary(0, "sapnwrfc.dll") And OpenConsole()
        
      For i = 0 To CountProgramParameters() - 1
        Select ProgramParameter(i)
          ; GatewayHost-------------------------------------------------
            Case "/g", "/G"
              GatewayHost = ProgramParameter(i + 1)
          ; GatewayService----------------------------------------------
            Case "/x", "/X"
              GatewayService = ProgramParameter(i + 1)
        EndSelect        
      Next
      
      PrintN("Example for a small SAP server from Stefan Schnell")
      PrintN("Host: " + GatewayHost + " / Service: " + GatewayService)
      PrintN("Break execution with Ctrl+C")
        
      hDesc = CallFunction(0, "RfcCreateFunctionDesc", @"ABAPCall", RfcErrorInfo)

      If hDesc And Trim(GatewayHost) <> "" And Trim(GatewayService) <> ""
      
        connParams(0)\name = @"program_id"
        connParams(0)\value = @"SMALLSERVER"
        connParams(1)\name = @"gwhost"
        connParams(1)\value = @GatewayHost
        connParams(2)\name = @"gwserv"
        connParams(2)\value = @GatewayService
        
        rc = CallFunction(0, "RfcInstallServerFunction", #Null, hDesc, @ABAPCall(), RfcErrorInfo)
            
        If rc = #RFC_OK
          hConn = CallFunction(0, "RfcRegisterServer", connParams(), 3, RfcErrorInfo)
          If hConn
            While rc =#RFC_OK Or rc = #RFC_RETRY
              rc = CallFunction(0, "RfcListenAndDispatch", hConn, 32, RfcErrorInfo)
              Select rc
                Case #RFC_OK
                  
                Case #RFC_RETRY

              EndSelect
            Wend
          EndIf
        EndIf  
        
      EndIf

      CloseLibrary(0)
      CloseConsole()
    EndIf  
    
; End-------------------------------------------------------------------
End

The Gateway and Customizing
To know the gateway service (gwserv) and the host (gwhost) use transaction code (TAC) SMGW and the menu Goto > Parameters > Display, look at the attribute entries gateway hostname and gateway service. Use these attributes to call the program. But before you call the program, insert in the file Windows\system32\drivers\etc\services the entry sapgw00 with 3300/tcp for sapgw00, or e.g. for sapgw99 3399/tcp. You must also customize with TAC SM59 the RFC destination SMALLSERVER.

Use the Function from ABAP
With one line code now we can use the server function from ABAP:

Code: Select all

"-Begin----------------------------------------------
  Report zSmallServerTest.

    Call Function 'ABAPCall' Destination 'SMALLSERVER'.

"-End------------------------------------------------

Summery
On the one hand the SAP server program is very small. The commented source has 96 lines code and the compiled console executable has a size of 9.728 bytes. On the other hand this example shows how easy it is, to code a SAP server. With these possibilities you can code your functions in PureBasic and use them in ABAP.

Links

• service.sap.com/connectors
• www.stschnell.de

Trademarks

• SAP, NetWeaver and ABAP are registered trademarks of SAP AG, Germany
• Microsoft and Visual C are registered trademarks of Microsoft Corporation, USA

You find this article in PDF here and the files here.

Cheers
Stefan

[Kukulkan]

Thanks! This may become very handy for me in the future (we think about such a project).

Kukulkan

[Amundo]

Interesting as always, Stefan, thanks for sharing, one of these days I might use this stuff at work...