[DFDL-WG] What are the consequences of a failed assert?

[Tim Kimber]

There are four types of error in DFDL:
- a Schema Definition Error : The schema itself is not valid. ( at least 
three kinds: xsd not valid, xsd not in the DFLD subset, DFDL annotations 
not following the rules )
- A Processing Error : The data cannot be parsed. Or if unparsing, the 
info set cannot be unparsed.
- A Recoverable Error : ( see the Errata ). This is effectively a 
user-defined form of Processing Error, raised while executing a DFDL 
assert, 
- A Validation Error : The info set does not conform to the XSD

A Processing Error or a Recoverable Error will cause the parser to 
backtrack to the nearest point of uncertainty. So it will only stop the 
parse if there are no points of uncertainty currently active.
A Schema Definition Error is immediately fatal. Most of these can be 
detected by the processor before parsing/unparsing begins.
A Validation Error is only reported if validation is enabled in the DFDL 
processor. It does not cause backtracking - the parser continues to parse 
after reporting the error.

That's the gist of it. Further details from other WG members may follow 
shortly, depending on how accurate I have managed to be.

regards,

Tim Kimber, DFDL Team,
Hursley, UK
Internet:  kimbert at uk.ibm.com
Tel. 01962-816742 
Internal tel. 37246742




From:   "Garriss Jr., James P." <jgarriss at mitre.org>
To:     "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>, 
Date:   03/07/2013 19:06
Subject:        [DFDL-WG] What are the consequences of a failed assert?
Sent by:        dfdl-wg-bounces at ogf.org



I have an element with an assert,
 
           <xsd:element name="Type" dfdl:inputValueCalc="{ 
fn:lower-case(../MixedCaseType) }">
                <xsd:annotation>
                    <xsd:appinfo source="http://www.ogf.org/dfdl/dfdl-1.0/
">
                        <dfdl:assert test="{ dfdl:checkConstraints(.) }" 
message="The type must match one of the values on the enumerated list."/>
                    </xsd:appinfo>
                </xsd:annotation>
                <xsd:simpleType>
                    <xsd:restriction base="xsd:string">
                        <xsd:enumeration value="application"/>
                        <xsd:enumeration value="multipart"/>
                        <xsd:enumeration value="message"/>
                        <xsd:enumeration value="text"/>
                    </xsd:restriction>
                </xsd:simpleType>
            </xsd:element>
 
and the assert is failing (as it should in this case!). 
 
Parse Error: Assertion failed. The type must match one of the values on 
the enumerated list.
 
What are the consequences of a failed assert?  I have an old version of 
the spec—is there a place to a get a current, complete copy?—but it says 
“An unsuccessful dfdl:assert causes a processing error.” 
 
1.     What does “processing error” mean in English? 
2.     Does it mean the input is invalid? 
3.     Does it mean the processor should stop here and go no further? 
4.     Does it mean the process should simply ignore the problem and move 
on to the next item in the schema? 
 
TIA
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