[saga-rg] exceptions...

[Andre Merzky]

Hi Pascal, 

thanks for the feedback! :-)

Cheers, Andre.


Quoting [Pascal Kleijer] (Feb 20 2006):
> Date: Mon, 20 Feb 2006 09:09:01 +0900
> From: Pascal Kleijer <k-pasukaru at ap.jp.nec.com>
> To: Andre Merzky <andre at merzky.net>
> CC: SAGA RG <saga-rg at ggf.org>
> Subject: Re: [saga-rg] exceptions...
> 
> Hello all,
> 
> Just to support Andre and Hartmut!
> 
> >  - if an exception is fatal or not depends on the use case
> >    ("Can't suspend job" - fatal or not?)
> 
> Exact. The API can in most cases not decide what it is. I have cases 
> where I consider a same exception as an internal signal and in order 
> cases I throw it upwards to the application. Unless you can clearly 
> identify "fatal" and eventually handle it, you should expose the problem 
> to the application.
> 
> 
> 
> >  - a non-fatal backend exception could be recovered from by
> >    the saga implementation, and would hence not reach the
> >    application - so we don't need it.  If we can't recover,
> >    it might well be fatal.
> 
> Yes, if the API can do nothing or don't know how to handle it, throw it 
> upward. Their might be cases where the SAGA implementation differs. For 
> example, if one implementation has disconnection recovery implemented 
> and another not, one might mute and recover from the exception when the 
> other will throw it.
> 
> 
> 
> >  - obviously bad things like 'not enough memory' don't need
> >    to be put into saga exceptions - have nothing to do with
> >    saga semantics.
> 
> Right, not in the API scope. In Java they are not even Exceptions but 
> Errors (Fatal) and they are unchecked. You can trap them and eventually 
> handle them, but in most cases it is hard to recover from them.
> 
> 
> 
> >So, I/we _think_ the agreement was to have only one simple
> >saga::exception class which gets thrown whenever something
> >happens which violates the semantic contract of a saga call.
> 
> The different implementation can always sub-class them to provide better 
> exception semantic. A single saga::exception class is more then enough.
> 
> Anyway you have my support on this.
-- 
"So much time, so little to do..."  -- Garfield