[saga-rg] task error handling...

5 Nov 2005

      Hi again, 

the task error handling is somewhat unclear in the spec.  We
had soe discussions with the GridRPC folx at GGF about that,
and I had some earlier notes.  So, here is what came out of
the discussions:

  - a running task does NEVER throw an error during its run
  - if a task meets an error condition, the error (or
    exception) is to be stored (if possible)
  - if an error is encountered by a task, the task state has
    to be changed to Failed
  - the throw () method causes the task to throw any error
    which was previously encountered.  In all states _but_
    in the Failed state the call does nothing.

  Example code looks like:

  {
    task.run  ();
    task.wait ();

    if ( task.get_status = saga::task::Failed )
    {
      try {
        task.throw ();
      }
      catch ( saga::exception e )
      { 
        std::cerr << "Oops!\n";
      }
    }
  }

  Note that the 'if' check for the task state is not
  required - for all other states the try would yield
  nothing.

Does anybody see problems with that approach?  Is it simple
enought?  The get_error method still exists, and returns the
error string (basically the string from exception.what() ).

Cheers, Andre.

-- 
+-----------------------------------------------------------------+
| Andre Merzky                      | phon: +31 - 20 - 598 - 7759 |
| Vrije Universiteit Amsterdam (VU) | fax : +31 - 20 - 598 - 7653 |
| Dept. of Computer Science         | mail: merzky@cs.vu.nl       |
| De Boelelaan 1083a                | www:  http://www.merzky.net |
| 1081 HV Amsterdam, Netherlands    |                             |
+-----------------------------------------------------------------+