[DFDL-WG] checking on 'no recursion' restriction - are we sure we can live without it

[Tim Kimber]

Recursion would help, but I suspect that you would still end up with a 
DFDL info set that was structured in a non-ideal way. The info set would 
be a tree in which all of the 'real' elements would have the same name. 
The JSON names would have to be carried on a child element 'jsonName'. 
Most clients applications would want to transform that DFDL info set into 
something more natural. One solution would be to add a new feature to DFDL 
to allow the info set element name to be calculated from the data using a 
DFDL expression - but then the DFDL info set would not be valid for the 
DFDL xsd.

Looking at this another way, JSON is like XML - they are both 
self-defining formats allowing arbitrarily deep nesting. In both cases you 
can add some external rules that describe the expected structure of the 
document ( e.g. XSD for XML ) .  I think DFDL is designed for the case 
where the structure is known in advance. The 'generic JSON parser' or 
'generic XML parser' are solved problems.

regards,

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




From:   Suman Kalia <kalia at ca.ibm.com>
To:     Mike Beckerle <mbeckerle.dfdl at gmail.com>
Cc:     dfdl-wg at ogf.org, dfdl-wg-bounces at ogf.org
Date:   09/04/2012 12:27
Subject:        Re: [DFDL-WG] checking on 'no recursion' restriction - are 
we sure we can live without it
Sent by:        dfdl-wg-bounces at ogf.org




I tried to search XML schema definition for JSON but could not find it.. 
If you have please attach.  You can build models without using recursion. 
Adding recursion to the spec will certainly increase complexity. 



From:        Mike Beckerle <mbeckerle.dfdl at gmail.com> 
To:        dfdl-wg at ogf.org 
Date:        04/06/2012 05:49 PM 
Subject:        [DFDL-WG] checking on 'no recursion' restriction - are we 
sure we can live without it 
Sent by:        dfdl-wg-bounces at ogf.org 




DFDL v1.0 spec currently disallows recursive types.

Are we sure we can live without this?

Seems to me there are many formats e.g., JSON, which are popular now, and 
which naturally require recursion to express.

There are a number of document-like formats - there's a fuzzy grey area 
where documents and data records overlap, and these will naturally be 
modeled using recursion.

Even formats like EDIFACT allow segment nesting, though I'm not sure about 
whether recursive definitions are allowed or precluded, a generic EDIFACT 
parser wouldn't know any specific segment types, and would want to have a 
recursively defined generic segment structure.

Comments?

...mikeb

-- 
Mike Beckerle | OGF DFDL WG Co-Chair 
Tel:  781-330-0412
--
 dfdl-wg mailing list
 dfdl-wg at ogf.org
 https://www.ogf.org/mailman/listinfo/dfdl-wg --
  dfdl-wg mailing list
  dfdl-wg at ogf.org
  https://www.ogf.org/mailman/listinfo/dfdl-wg






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





-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.ogf.org/pipermail/dfdl-wg/attachments/20120409/fc6ba3a8/attachment.html>