[DFDL-WG] questions

[Steve Hanson]

I am not aware of a formal comparison with smooks.

For partial parsing you use a loop of parseNext() calls instead of a 
single parseAll() call. That puts you in control of how far down the data 
you parse. In the Java sample provided with IBM DFDL, the code to do this 
is present but commented out.

Two things can happen when a processing error occurs. If inside a point of 
uncertainty, such as a choice branch or an optional element, then the 
processing error is taken to indicate that the component does not exist, 
and the parser then backtracks and tries an alternative (so the error is 
suppressed). If not inside a point of uncertainty, then IBM's parser 
currently treats that as a fatal error and stops the parse. The spec 
(section 2.1) allows for more creative behaviour:

It is expected that DFDL implementations will provide additional 
mechanisms for dealing with effective processing errors, such as the means 
of specifying retry points or the means of skipping some data so as to 
recover from the error in some way. The DFDL specification language does 
not provide features for specify such mechanisms 

If the data is well-formed (ie, no processing error occurs), then 
switching on validation will report all validation errors (section 2.5).

It is possible using an assert to throw a recoverable error after which 
the parser will continue (section 2.5).

Regards
 
Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848



From:   Bing Lu <mfcplus at yahoo.com>
To:     "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>, 
Date:   30/04/2014 02:11
Subject:        [DFDL-WG] questions
Sent by:        dfdl-wg-bounces at ogf.org



Just curious, has anyone in the group compared DFDL with smooks, pro and 
cons? Also I were to parse the DFDL using IBM DFDL code, is there a 
setting that I can call to do partial parsing? And when parsing happens, 
does it stop on the first parsing error or it tries to parse as much as 
possible to include all the errors encountered? thanks--
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