Async Call
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Size :  9Kb
Level :  stable
Version :  1.1
Date :  10-Sep-2004


This is an asynchronous CALL function implementation. That means that it does the same job as the native CALL command, but allows you to retrieve output data without blocking your REBOL session. Furthermore, you can execute several system calls at the same time while running a View event loop !

A simple callback system is provided. It allows you to process output data in a "streamed" way without having to wait for called command to finish.


  • Port handler (call:// scheme).
  • Simple Event API.
  • Ability to hide the DOS console window.
  • Can run multiple external commands at the same time.
  • Compatible with /View event loop.
  • Requires /Library component! (needs /Pro, /Command or /SDK).
  • Windows platform only!.
  • Version 1.0 has a largely commented source code. (See History section)


  • While running an external command, there's a polling loop working that can raise your CPU usage close to 100%. We do not recommend the use of this library for long lasting tasks.

  • It has been reported that the use of this library may prevent an async port from working correctly...This issue needs to be investigate further.


  • v.1.1 - 10/09/2004
    - Fixed a bug that keeps the port busy when the external process has finished. Thanks to Graham Chiu for reporting.
    - Documentation examples fixed.

  • v.1.0 - 17/02/2004
    - First public release.
    - Documentation and commented version added.

  • v.0.9.1 - 11/02/2004
    - Bugfix: a buffer overflow was causing some output bytes to be missed. Thanks to Gabriele Santilli for reporting the bug.
    - Code minor clean-up.

  • v.0.9 - 10/02/2004
    - First public beta release