[DFDL-WG] Agenda for OGF DFDL WG call 14 April 2010- 13:00 UK (8:00 ET)

Tue Apr 13 11:16:45 CDT 2010

1. DFDL Specification status
There has been no announcement of the public comment period so presumably 
it hasn't started. Chasing email sent.

2 Nils, defaults and unparsing 

Logical Value

initiator region contains
content region contains
Nil
(implies nillable)
nilValueInitiatorPolicy 
'prohibited'
empty
representation of nil 
nilValueInitiatorPolicy 
'required'
initiator string
"" (empty string)
(type is xs:string or xs:hexBinary)
missingValueInitiatorPolicy 
'prohibited'
empty
empty 
missingValueInitiatorPolicy 
'required'
initiator string 
missing
useNilForDefault
nilValueInitiatorPolicy 
'prohibited'
empty
representation of nil 
nilValueInitiatorPolicy 
'required'
initiator string
default is empty string
(type is xs:string or xs:hexBinary)
missingValueInitiatorPolicy  'prohibited'
empty
empty
missingValueInitiatorPolicy 'required'
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

Other changes: 

missingValueInitiatorPolicy 
Enum 
Valid values ?required', ?prohibited' 

Specifies whether to expect an initiator when an element is missing. 
Ignored unless dfdl:initiator is specified and is not "" (empty string). 

'required'- Indicates that the dfdl:initiator followed by empty content is 
the required syntax to indicate that the element is missing. 

?prohibited' - Indicates that empty content is the required syntax to 
indicate that the element is missing. The presence of an initiator implies 
that real content must follow. 
Use of ?prohibited' implies an ordered sequence. If used on an initiated 
element of an unordered group it is a schema definition error. 

If the element is required, defaulting occurs as defined above. 
This property also applies on unparsing, when the data to be written 
(after nil value and default value processing) is empty content.

Annotation: dfdl:element 

Need to decide  whether there needs to be a differentiation between 'zero 
length content' and 'missing from the data stream'. 
Tim will document the parsing use cases so we can verify the parsing 
table. 

3 dfdl:separatorPoilicy. 

dfdl:separatorPolicy enumeration definitions are not complete as they do 
not discuss arrays or defaulting. 

separatorPolicy="required" 
All the separators must be there.
No group member, except for required members with a default,  may be 
omitted from the data stream. 
Every group member must have a separator in the correct position. 
Optional members and variable-occurrence arrays will be allowed, 
separators will be expected for all maxOccurs 
** It is a schema definition error if maxOccurs="unbounded" for any member 
of the group 

separatorPolicy="suppressed" 
Any group member ( optional or required with a default) can be omitted 
from the data stream, in which case its separator must  may also be 
omitted. 

For prefix and infix, if a separator is found then another group member is 
expected. 
For postfix, if enclosing markup is not found immediately after a postfix 
separator then another group member is expected. 

Enclosing markup or end of data can occur where an infix or prefix 
separator is expected. This terminates the group. 
Enclosing markup or end of data can occur immediately after a postfix 
separator (if dfdl:documentfinalSeparatorCanBeMissing is 'yes' then the 
postfix separator may be missing at the end of the datastream). This 
terminates the group. 

If the group terminates before all of its members have been parsed then 
any required members in the remainder of the group must be defaulted into 
the infoset. 
The entire group can have a zero-length representation, which is indicated 
by enclosing markup at the start of the group's content region. 

If another group member is expected and the next group member is a point 
of uncertainty then the identity of the next group member must be 
determined 
by resolving the point of uncertainty as described in section XXX. 

If another group member is expected but no group member is found in the 
data stream then it is a processing error. 
If another group member is expected but all group members have been parsed 
then it is a processing error. 

separatorPolicy="suppressedAtEnd" 
suppressAtEnd has the same rules as 'required' up to the last required 
member that does not have a default, then it has the same rules as 
'suppressed' 

Open questions 
1. If a group has separatorPolicy='required' and one of its optional 
members has a zero-length representation, and that member is allowed to 
have a zero-length representation, what should the parser do?   
A similar question arises for required, defaultable elements with a 
zero-length representation when they are based on a type with 
xs:minLength="0". Should the default value be used, or the empty string? 
2. How should the occursXXX properties be applied when there are other 
ways to determine the number of occurences ( e.g. by counting separators 
)? 
3. What algorithm should the parser use to decide whether to default a 
complex element or group ( when the element/group is a child of a 
separated group)? 
4. How does unparsing work for separated groups in all of these scenarios? 

4 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.
....
31/03: work is progressing
084
Check behaviour of dfdl:inputValueCalc and outputValueCalc.
085
ALL: publicize Public comments phase to ensure a good review..
086
AP: Nils and Defaults during unparsing - update table
31/03: TK to document use cases for parsing

088
define semantics of choiceKind 'fixedLength' 
31/03: TK to provide definition of calculable length.
Investigate  PL/I varchars and Cobol occurs dependingon.

089
Need to be able to define unsigned decimal and integer
31/03: MB to agree proposed solution

090
Semantics of separatorPolicy

Regards

Alan Powell

Development - MQSeries, Message Broker, ESB
IBM Software Group, Application and Integration Middleware Software
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