Could you give me some hints for a schedule program? We don't have enough time to experiment much.

For a Windows environment, three options come to mind:

• You could use the Windows Task Scheduler; through the dialog Advanced Settings, you can set a schedule to x times an hour. Within Windows 2000 this functionality is available through the Control Panel, with Windows NT you might have a folder named Tasks under the WinNT folder with the same behavior (probably depends on the Service Pack level).
• With VBScript 5 (Windows Scripting Host 2.0) you build a script that uses an infinite loop and pauses with WScript.Sleep milliseconds. Since the argument is an Integer, you must repeat this command several times to achieve a pause of 15 minutes. Note, however, that the Sleep method uses no processor time.
  When activated through cscript.exe, it's possible to stop the script with Ctrl+Break.
  To get a more interactive program, you could use a semaphore file to trigger the deactivation of the script:

  tbxdsr.vbs /start

  • Checks for the existence of the semaphore. If present: break off execution and display an error message stating: "Already active".
  • Create empty semaphore file.
  • Begin infintie loop, with pause; every iteration you should check for existence of the semaphore, and if it is no longer present: abort

  tbxdsr.vbs /stop

  Checks for the presence of the semaphore file, and deletes it (if present).

  If you start these scripts through a shortcut, with wscript.exe, no command line will be shown.
  With a little tweaking, you could even use the semaphore file to indicate the status of the requestor (e.g., /status says "Retrieving" or "Sleeping"). You could also use a registry key instead of a file.
• Visual Basic contains a simple Timer control. If you create a simple Form with the Timer control (since the timer control suffers the same limitations as the WScript.Sleep method, you'll need to count the number of timer events), and a simple on/off button. You could then start the program/script every (legal) timer event. Given some time, you can incorporate the functionality of the parser in this program as well.

For other operating systems, there exist similar options.