Re: Forms USER_EXIT / calling a DLL from Forms 4.5

On Thu, 8 Jan 1998 10:54:00 +0100, "Joachim Hasler" <jha_at_futuresoft.de> wrote:

user exists are not exactly what you want. If you do not need to maintain a transaction state with forms in your DLL - then don't use a user exit. Instead use a foriegn function. here is an example:

• ********************************************************* --
• This would be the calling trigger's code --
• ********************************************************* --

declare

• Parameters parm1 VARCHAR2(200) := 'Something';
• Return value rt PLS_INTEGER; begin rt := MyLib.MyFunc1( parm1 ); end;
  • ********************************************************* --
  • This would be the wrapper package header code --
  • ********************************************************* --

PACKAGE MYLIB IS
    FUNCTION MyFunc1( parm1 IN OUT VARCHAR2 )

                    RETURN PLS_INTEGER;  

• ********************************************************* --
• This would be the wrapper package body code --
• ********************************************************* --

PACKAGE BODY MYLIB IS
  lib_hndl ora_ffi.libHandleType;
  func_hndl ora_ffi.funcHandleType;   

• Note that we always pass a function handle in as the first parameter FUNCTION i_MyFunc1( func_hndl IN ora_ffi.funcHandleType, parm1 IN OUT VARCHAR2 ) RETURN PLS_INTEGER;
• This pragma is identical (except the function name) for all ORA_FFI functions PRAGMA INTERFACE(C,i_MyFunc1,11265);

  FUNCTION MyFunc1( parm1 IN OUT VARCHAR2 )

                    RETURN PLS_INTEGER   
  IS   
    rc       PLS_INTEGER;  

• Note that the function handle is the first parameter in the call rc := i_MyFunc1(func_hndl, parm1); RETURN (rc); END ;

• Load the library ... like WinAPI LoadLibrary() lib_hndl := ora_ffi.load_library(NULL,'D:\TESTCASE\MYDLL\DEBUG\MYDLL.DLL');
• Register the target function ... like WinAPI GetProcAddress()
• Note: The function name (eg. mytest) IS case sensitve in Win32 func_hndl := ora_ffi.register_function(lib_hndl,'mytest',ora_ffi.C_STD);
• Denote the parameter list ora_ffi.register_parameter(func_hndl,ORA_FFI.C_CHAR_PTR);
• Denote the return value ora_ffi.register_return(func_hndl,ORA_FFI.C_INT); END;
  • ********************************************************* --
  • This would be the C++ code for the Win32 DLL --
  • ********************************************************* --

/*
**  Note: It is important that this file be compiled as a .C file
**        or the exported functions -must- be wrapped so that they
**        are compiled as C style functions. Failure to do this
**        will result in mangled naming.

#include <windows.h>

extern "C"
{
int _declspec(dllexport) mytest(char* p_string); }

BOOL WINAPI DllMain(HANDLE hInst, ULONG ul_reason_for_call, LPVOID lpReserved)
{

        if ( ul_reason_for_call == DLL_PROCESS_ATTACH )
                MessageBox(NULL,"Hello","Startup",MB_OK);

        return 1;

int _declspec(dllexport) mytest(char* p_string) {

                MessageBox(NULL,p_string,"Function",MB_OK);

        return 0;

--mark

>Hi everybody,
>
>our customer uses a self written application under Forms 4.5 (WfW 3.11). On
>a button-click it is necessary to call a DLL with some parameters. This DLL
>will display some information on the screen. The user will switch back to
>the Forms-application by Alt+TAB.
>
>We have the knowledge to write DLLs in C or C++, but we don't know how to
>call a DLL from a Forms-application (we have no knowledge about Forms at
>all). There is a functionality called USER_EXIT. But the Oracle-sample(s)
>ue_samp.mak does not work, missing files...
>
>Can anybody help with some sample-codes?
>
>
>
>Joachim Hasler
>jha_at_futuresoft.de
>