3. Current Actions:
4 Expressions during Unparsing.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. DFDL Specification status
2 Nils, defaults and unparsing
Steve H, Tim and Alan have had further
discussions and concluded and new property was not required so propose
- Elements that are zero length and
elements that are 'missing' from the data stream should be treated the
same.
- missingValueInitiatorPolicy should
be renamed to emptyValueInitiatorPolicy to distinguish from a missing infoset
value on unparsing
- Any 'initiator' policy needs to also
include terminators so the enumerations should be extended to "none",
"initiator", "terminator", "both". and the
properties renamed emptyValueDelimiterPolicy and nilValueDelimiterPolicy
.
The tables have been reworked
Nils and Defaults on Parsing
|
initiator region
|
content region
|
Logical Value
| ||
|
matching
|
content
|
content matches nilValue
|
nilValueDelimiterPolicy
must be initiator or both |
nil
|
|
Content does not match nilValue |
parse content to get value
| |||
|
matching
|
empty
|
empty string is a nil value
|
nilValueDelimiterPolicy
must be initiator or both |
nil
|
|
A default is specified
|
emptyValueDelimiterPolicy
must be initiator or both |
default value
(may be nil, empty space or value) | ||
|
empty
|
content
|
content matches nilValue
|
nilValueDelimiterPolicy
must be none |
nil
|
|
content does not match nilValue
|
Initiator is not specified
|
parse content to get value
| ||
|
Initiator is specified
|
ERROR
| |||
|
empty
|
empty
| empty string is a nil value |
nilValueDelimiterPolicy
must be none |
nil
|
|
A default is specified
|
emptyValueDelimiterPolicy
must be none |
default value
(may be nil, empty space or value) | ||
|
Logical Value
|
initiator region contains
|
content region contains
| ||
|
Nil
(implies nillable) |
nilValueDelimiterPolicy
none |
empty
|
representation of nil
| |
|
nilValueDelimiterPolicy
initiator or both |
initiator string
| |||
|
"" (empty string)
(type is xs:string or xs:hexBinary) |
emptyValueDelimiterPolicy
none |
empty
|
empty
| |
|
emptyValueDelimiterPolicy
initiator or both |
initiator string
| |||
|
missing
|
useNilForDefault
|
nilValueDelimiterPolicy
none |
empty
|
representation of nil
|
|
nilValueDelimiterPolicy
initiator or both |
initiator string
| |||
|
default is empty string
(type is xs:string or xs:hexBinary) |
emptyValueDelimiterPolicy
none |
empty
|
empty
| |
|
emptyValueDelimiterPolicy
initiator or both |
initiator string
| |||
|
Other default
|
initiator string
|
representation of the
default value.
| ||
|
a non-nil non-empty-string
value
|
initiator string
|
representation of the logical
value | ||
3. Current Actions:
|
No
| Action |
|
066
| Investigate format for defining test
cases
25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. |
|
084
| Check behaviour of dfdl:inputValueCalc
and outputValueCalc.
14/04: no prorgess |
|
085
| ALL: publicize Public comments phase
to ensure a good review..
14/04: see minutes |
|
086
| AP: Nils and Defaults during unparsing
- update table
31/03: TK to documetn use cases for parsing 14/04: Investigate new property to control empty string behaviour. |
|
088
| define semantics of choiceKind 'fixedLength'
31/03: TK to provide definition of calculable length. Investigate PL/I varchars and Cobol occurs dependingon. 14/04Tim had distributed a document starting the definition of calculable length for the longest choice member. Alan had done some investigation of COBOL occurs depending on and when used in the working section of a program then the maximum storage was reserved but when used in the linkage section the dependent number was uses. We need to understand how the WMB COBOL importer deals with ODO. |
|
089
| Need to be able to define unsigned decimal
and integer
31/03: MB to agree proposed solution 14/04: MB to agree proposed solution |
|
090
| Semantics of separatorPolicy
14/04: Discussion on detecting when complex types should be defaulted. Examples needed. |
4 Expressions during Unparsing.
In order to reduce complexity and potential
performance problems it is proposed to
- nilValue and occursStopValue
should NOT be able to take an expression.
- Very few properties should be allowed
to have forward references.
Here's the list of properties that can
take an expression, along with some suggested restrictions on forward referencing:
| byteOrder | backward reference only |
| encoding | backward reference only |
| initiator | backward reference only |
| terminator | backward reference only |
| separator | backward reference only |
| outputNewline | backward reference only |
| length | simple elements : backward reference
only.
complex elements : forward reference allowed Quote "When unparsing with dfdl:lengthKind="explicit", the calculation of dfdl:representationLength() returns the value of the dfdl:length property." A simple element's length needs to be known in advance, else it cannot be parsed. A complex element's length might get resolved while parsing its content, so a forward reference within the scope of the complex element is possible. Having said that, we might want to impose a restriction in IBM's DFDL processor v1.0 that only backward references are allowed. |
| escapeCharacter | backward reference only |
| escapeEscapeCharacter | backward reference only |
| textNumberDecimalSeparator | backward reference only |
| textNumberGroupSeparator | backward reference only |
| textNumberExponentCharacter | backward reference only |
| binaryFloatRep | backward reference only |
| textBooleanTrueRep | backward reference only |
| textBooleanFalseRep | backward reference only |
| nilValue | backward reference only
Not clear why this needs to be specified as an expression. ( may already be on a list of open issues somewhere ) |
| nilIndicatorPath | backward reference only |
| occursCount | backward reference only |
| occursStopValue | Not clear why this needs to be specified as an expression. |
| [inputValueCalc] | [Parser only] Backward reference only |
| outputValueCalc | Forward or backward reference |
| Regards
|
| Alan Powell |
| Development - MQSeries, Message Broker, ESB |
| IBM Software Group, Application and Integration Middleware Software |
| ------------------------------------------------------------------------------------------------------------------------------------------- |
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| Hursley, SO21 2JN |
| United Kingdom |
| Phone: +44-1962-815073 |
| e-mail: alan_powell@uk.ibm.com |
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