[DFDL-WG] Parsing Rules for resolving points of uncertainty

Tue Oct 6 16:44:56 CDT 2009

- I'd like to see a version in which the comments are addressed and 
removed.
- typo in para 1 : 'neatest'
- 'A point of uncertainty is caused'. Probably better to say that it is 
'opened' or 'started'.
- para which begins 'For an optional element' has a repeated phrase 
towards the end.
- I was assuming that any processing error, of any kind, relating to any 
physical region, would cause backtracking to the nearest point of 
uncertainty. 
If there is any set of processing errors that *doesn't* cause 
backtracking, that set should be described in this doc.
- Should have a statement about how validation errors affect points of 
uncertainty. I'm assuming that they don't ( either the parse is 
immediately stopped by the host application, or the validation error is 
ignored)
- Should have a statement about how schema definition errors, if detected 
by the DFDL parser, affect points of uncertainty. I'm assuming that they 
are treated exactly like a processsing error, and cause backtracking to 
occur in the normal way.

regards,

Tim Kimber, Common Transformation Team,
Hursley, UK
Internet:  kimbert at uk.ibm.com
Tel. 01962-816742 
Internal tel. 246742

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Date:
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Today's Topics:

   1. DFDL Specification draft v1.036 available (Alan Powell)
   2. Parsing Rules for resolving points of uncertainty V2 (Alan Powell)

----- Message from Alan Powell <alan_powell at uk.ibm.com> on Tue, 6 Oct 2009 
14:46:36 +0100 -----
To:
dfdl-wg at ogf.org
Subject:
[DFDL-WG] DFDL Specification draft v1.036 available

Draft 036 of the DFDL Specification V1 is available but unfortunately 
sourceforge seems to be having problems again so I cannot upload it. If 
you need a copy please send me an email. 

Alan Powell

MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM     email: alan_powell at uk.ibm.com 
Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898

Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU 

----- Message from Alan Powell <alan_powell at uk.ibm.com> on Tue, 6 Oct 2009 
18:16:59 +0100 -----
To:
dfdl-wg at ogf.org
Subject:
[DFDL-WG] Parsing Rules for resolving points of uncertainty V2

Updated proposal based on comments 

Alan Powell

MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM     email: alan_powell at uk.ibm.com 
Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898

----- Forwarded by Alan Powell/UK/IBM on 06/10/2009 18:15 ----- 
From: 
Steve Hanson/UK/IBM 
To: 
Tim Kimber/UK/IBM at IBMGB 
Cc: 
Alan Powell/UK/IBM at IBMGB, Suman Kalia/Toronto/IBM at IBMCA, Mike Beckerle 
<mbeckerle.dfdl at gmail.com>, Peter Lambros/UK/IBM at IBMGB, 
steve.marting at progeny.net 
Date: 
30/09/2009 10:31 
Subject: 
Re: Parsing Rules for resolving points of uncertainty (speculative 
parsing)

Some more comments in here. 

Steve copied in as will be discussed on call today. 

[attachment "Resolving Uncertainty v1.doc" deleted by Alan Powell/UK/IBM] 

Regards

Steve Hanson
Programming Model Architect, WebSphere Message  Brokers,
OGF DFDL WG Co-Chair,
Hursley, UK,
Internet: smh at uk.ibm.com,
Phone (+44)/(0) 1962-815848 

From: 
Tim Kimber/UK/IBM 
To: 
Mike Beckerle <mbeckerle.dfdl at gmail.com> 
Cc: 
Alan Powell/UK/IBM at IBMGB, Suman Kalia <kalia at ca.ibm.com>, Peter 
Lambros/UK/IBM at IBMGB, Robert Connolly <rconnoll at us.ibm.com>, Steve 
Hanson/UK/IBM at IBMGB 
Date: 
28/09/2009 14:20 
Subject: 
Re: Parsing Rules for resolving points of uncertainty (speculative 
parsing)

re: Mike's point, I would suggest 
- member of a choice group/unordered group/group containing floating 
elements: scope of uncertainty is the scope of the element 
- optional occurrence : parser tries first to parse another occurrence, 
and the scope of uncertainty is the scope of the element. Secondly, parser 
tries to parse the item following the element ( which may be a group ) and 
the scope of uncertainty is the scope of that element/group. 

re: Alan's draft, I think the final para could be replaced with the 
following two statements: 
- if a processing error is encountered while parsing an option, the parser 
will back up and try the next option. If there are no further options, the 
processing error will propagate out to the next enclosing point of 
uncertainty. 
- a dfdl:assert can be used to trigger a processing error. If the 
expression evaluates to false, the parser will behave exactly as if a 
normal processing error had been encountered. 

Wording can probably be improved... 

regards,

Tim Kimber, Common Transformation Team,
Hursley, UK
Internet:  kimbert at uk.ibm.com
Tel. 01962-816742 
Internal tel. 246742

From: 
Mike Beckerle <mbeckerle.dfdl at gmail.com> 
To: 
Alan Powell/UK/IBM at IBMGB 
Cc: 
Steve Hanson/UK/IBM at IBMGB, Tim Kimber/UK/IBM at IBMGB, Robert Connolly 
<rconnoll at us.ibm.com>, Peter Lambros/UK/IBM at IBMGB, Suman Kalia 
<kalia at ca.ibm.com> 
Date: 
25/09/2009 21:53 
Subject: 
Re: Parsing Rules for resolving points of uncertainty (speculative 
parsing)

Some feedback attached. 

We need some notion of the region of uncertainty, so we can discuss where 
assertions and discriminators have effect, and so we can say when the 
uncertainty ends and we no longer consider backtracking that region just 
because we finished without processing error. 

On Fri, Sep 25, 2009 at 11:51 AM, Alan Powell <alan_powell at uk.ibm.com> 
wrote: 

Guys  (limited distribution initially) 

I have simplified the previous speculative parsing description into a set 
of simple rules. 

Discussion points 
1.        Deemed to be found rule 1 'All the components of the option are 
found' could severely limit the ability to do partial parsing as it 
includes everything up to the terminator. 
2.        Do all/more the processing errors need to be listed for Not 
Found rule 3? 

Alan Powell

MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM     email: alan_powell at uk.ibm.com 
Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898

Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU 

[attachment "Resolving Uncertainty v1.doc" deleted by Tim Kimber/UK/IBM] 
[attachment "Resolving Uncertainty v1.doc" deleted by Steve Hanson/UK/IBM] 

Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU 

[attachment "Resolving Uncertainty v2.doc" deleted by Tim Kimber/UK/IBM] 
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