Re: Help: run a host program from a (client) trigger

In article <glasstetter.11.000E99B2_at_bmcwest.com> glasstetter_at_bmcwest.com (Dan Glasstetter) writes:
>In article <2hp2hd$aao_at_terminator.rs.itd.umich.edu> Liang Lin <llin_at_med.umich.edu> writes:
>>How do I execute a VMS program from an Oracle trigger?
>>Is there any way to write data into a disk file from a trigger?
>>Liang Lin
>We are having the same problem....
>How do we execute a Server command (VAX VMS) from the Client application
>(Forms 4.0) ?
>The HOST command from Forms executes in DOS.
>I've tried putting the HOST command in a database procedure with no luck.
>There has GOT to be a way to do this. We need to kick off a batch job
>(on the VAX) based upon user input (in the form).
>Can anyone out there shed some light ?
>Thanks,
>Dan Glasstetter
>BMC West Corp.
>glasstetter_at_bmcwest.com

HOST() is a built-in in our 4GL tools that executes client commands (on Windows, you also have the option of using DDE.EXECUTE(), which has slightly different, but necessary-on-Windows, behavior). If you want to execute commands on the server, one way is to create a server stored procedure which is called from the client when you want to execute a host-based operating system command. You can do this from the stored procedure by using DBMS_PIPE on the server. Then you create a program on the server using Pro*3GL or OCI, which waits on the DBMS_PIPE for a message from the server. When it gets that message through the pipe, it can then execute (using the equivalent of a Unix system() or exec() call) whatever program you like on the server.

pseudo code:

stored procedure:

procedure queue_batch_job (job_to_queue in char) is begin
  ...
  dbms_pipe(...); -- send message through pipe to daemon

• waiting to issue command ... end;

client code in Forms:

begin
  ...
  queue_batch_job (...); -- job to run
  ...
end;

daemon to run batch commands on host:

...
int main (...)
{
  ...
  while (/* didn't get quit message in pipe */)   {
    /* wait on DBMS_PIPE -- see example in manuals */     ...
    system (...);
    ...
  }
 ...
}

See the Oracle7 reference manual for examples of how to do this and how else to use DBMS_PIPE.

Good luck!

• Dennis Moore, etcetcetc