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Subject: Re: [wsbpel] Issue 190 - BPEL Internal Faults (New Proposed IssueAnnouncement)

I think the idea is not to get into the business of specifying the magic
switch but to recognize that real world engines will need to provided it.
Any solution that relaxes the requirement to process this situations as
formal faults would help. I like Dieter's proposal in particular but I
don't think that is the one. For example, a process author may be given the
ability may decide if he/she wants to explicitly take control of system
faults or not - that would also help. My point is that the current
situation forces process authors to do this and disallows other forms of
engine support.


                      "Yaron Y. Goland"                                                                                                 
                      <ygoland@bea.com>        To:       Francisco Curbera/Watson/IBM@IBMUS                                             
                                               cc:       Prasad Yendluri <pyendluri@webmethods.com>, Danny van der Rijn                 
                      02/07/2005 03:12          <dannyv@tibco.com>, wsbpel@lists.oasis-open.org                                         
                      PM                       Subject:  Re: [wsbpel] Issue 190 - BPEL Internal Faults (New Proposed Issue              
                      Please respond to         Announcement)                                                                           

I think the core of the problem is another part of our ever increasing

Lots of systems are going to have a magic switch that I strongly
encourage us not to attempt to specify in BPEL both because it's at
least 80% out of scope and because it will take a long time to agree on
the semantics.

That switch will specify (either on a process level or perhaps a scope
level) what to do if certain kinds of faults are thrown. One of the key
faults this switch will focus on are system faults.

This switch will typically have at least two settings.

Setting #1 - If a system fault is thrown immediately freeze the process
and call the admin for help who can then edit the process to fix things.

Setting #2 - If a system fault is thrown then send a note to the admin
but let the fault go through the normal fault handlers.

Both the first and second settings are possible with the existing spec.
The first behavior through an out of scope operational override and the
second behavior is pretty much our default behavior.

Issue 190 would make the second setting effectively impossible since it
would be illegal to ever allow system faults to go through normal fault
handling. But as Alex and others have convincingly argued there are many
interesting cases in which it makes sense to allow system faults to go
through normal fault handling.

In terms of maximizing portability I think we should stick with our
current behavior and leave the 190 style behavior to out of scope


Francisco Curbera wrote:
> I guess one of the points of the immediate termination condition is that
> termination is essentially always invisible to partners of the process.
> net effect of this change (and from my perspective the actual aim of this
> proposal) would be to allow engines the flexibility to deciding how to
> with these situations, termination being an option. Any form of standard
> fault semantics limit that flexibility because the engine would be forced
> to follow the usual scope termination/fault propagation behavior with
> likely the result of discarding many recoverable process instances - and
> posisble days or months of process work.
> Paco

>                       Prasad
> Yendluri

>                       <pyendluri@webmet        To:       Francisco
> Curbera/Watson/IBM@IBMUS
>                       hods.com>                cc:       Danny van der
> <dannyv@tibco.com>, wsbpel@lists.oasis-open.org
>                                                Subject:  Re: [wsbpel]
Issue 190
> - BPEL Internal Faults (New Proposed Issue
>                       02/04/2005 02:30
> Announcement)

> PM


> Hi,
> 1. Isn't this the same issue as the one raised by issue 187 where we ask
> there are any constraints in handling of the standard faults? This is
> proposing a specific resolution where it is recommended that the process
> always terminates immediately.
> 2.  I tend to side with Danny on this. I don't think we should require
> the process terminates immediately always. IMO in at least certain cases
> this may not be a fatal situation for the whole process (it could be
> confined to the scope) and other parts of the process may be able to
> continue by compensating for pertinent. Perhaps the impact could limited
> the immediately confining scope and the process could continue, perhaps
> area the fault occurred could be non-fatal to whole process (e.g. related
> look-up rather than modification of any information) or caused by some
> transient condition that could go away on a retry etc. I think the
> (fault handler) should be given a chance to handle the situation rather
> than terminate always.
> 3. If we do end-up going the "terminate" always way, we must minimally
> *not* preclude logging the condition, which could be more intelligent if
> the faults could be attached some "fault data" (ref issues 187 and 185).
> Regards, Prasad
> -------- Original Message --------

>  Subject Re: [wsbpel] Issue 190 - BPEL Internal Faults (New Proposed
>        : Announcement


>    Date: Fri, 4 Feb 2005 13:23:17 -0500


>    From: Francisco Curbera <curbera@us.ibm.com>


>      To: Danny van der Rijn <dannyv@tibco.com>


>      CC: wsbpel@lists.oasis-open.org


> Hi Danny,
> BPEL so far does not support any technique for modularizing process
> authoring, so the situation you describe is a bit out of scope right now.
> In any case, my view is that the idea that authors of business process
> going to be adding code to deal with things like unsupportedReference is
> just not realistic. I would even argue that those faults don't actually
> belong at the BP modeling level and need to be dealt with in a different
> way.
> Dieter's suggestion allows implementations to manage these situations in
> the best possible way.  This is specially important in the case of long
> running processes, where months or years of work can be thrown out the
> window when one of these faults is encountered (the current semantics
> require the complete unwinding of the execution stack if the fault is not
> caught and a generic catch all is essentially good for nothing).
> you want to allow manual intervention to figure out whether the process
> be repaired, terminated if not.
> Paco
>  >From: Danny van der Rijn
>  >To:       wsbpel@lists.oasis-open.org
>  >cc:
>  >Subject:  Re: [wsbpel] Issue 190 - BPEL Internal Faults (New Proposed
> Issue Announcement
>         02/03/2005 01:47 PM
> [Resending this with appropriate header to save Tony/Peter the trouble]
> -1
> As I pointed out in our last face to face, this kind of approach will
> any kind of modularization extremely difficult.  It will give no way for
> developer of a piece of BPEL code to protect against the "modelling
> (legacy term: "programming error") of another modeller whose attempt to
> model the real world failed in a tangible instance.
> Danny
> Tony Fletcher wrote:
>       This issue has been added to the wsbpel issue list with a status of
>       "received". The status will be changed to "open" if the TC accepts
>       as identifying a bug in the spec or decides it should be accepted
>       specially. Otherwise it will be closed without further
>       (but will be marked as "Revisitable")
>       The issues list is posted as a Technical Committee document to the
>       OASIS WSBPEL TC pages on a regular basis. The current edition, as a
>       TC document, is the most recent version of the document entitled in
>       the "Issues" folder of the WSBPEL TC document list - the next
>       as a TC document will include this issue. The list editor's working
>       copy, which will normally include an issue when it is announced, is
>       available at this constant URL.
>       Issue 190: BPEL Internal Faults
>       Status: received
>       Date added: 3 Feb 2005
>       Categories: Fault handling
>       Date submitted: 3 February 2005
>       Submitter: Dieter Koenig1
>       Document: WS-BPEL Working Draft, December, 2004
>       Related Issues: Issue 163 : languageExecutionFault, Issue 169 :
>       Transition condition error handling clarification, and Issue 187 :
>       Legality of Explicitly throwing or rethrowing Standard faults.
>       Description:
>       There are a number of cases in the current spec where the behavior
>       a process is described as *undefined*, in particular, after
>       recognizing internal errors described as standard faults.
>       With the exception of "bpel:joinFailure", *all* of these situations
>       represent modelling errors that cannot be dealt with by the
>       process itself in a meaningful way. This behavior becomes even more
>       questionable for catchAll handlers that try to deal with multiple
>       application faults and unexpectedly encounter a standard fault.
>       Submitter's proposal: Instead of allowing processes to catch these
>       standard faults, we propose that the process instance must
>       *terminate* immediately when such a situation is encountered.
>       The behavior of terminate is well-defined in BPEL -- as far as BPEL
>       is concerned the instance execution ends when terminate is
>       encountered without any fault handling behavior. Any additional
>       facilities for extended support for, e.g., repair and continue, is
>       definitely out of scope.
>       This approach would also create a clear direction for dealing with
>       any pathological situation within an inlined language (Issue 163)
>       therefore also for errors within transition conditions (Issue 169).
>       Changes: 3 Feb 2005 - new issue
>       Best Regards,
>       Tony
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