Open Grid Forum: Data Format Description Language Working Group
OGF DFDL Working Group Call, Oct-07-2009
Attendees
Mike Beckerle (Oco)
Alan Powell (IBM)
Steve Hanson (IBM)
Peter Lambros (IBM)
Stephanie Fetzer(IBM)
Apologies
Steve Marting (Progeny)
Suman Kalia (IBM)
051 - New scoping rules
A number of emails have pointed out minor flaws in the proposal from last
week so we spent most of the call refining the proposal.
1. Top level xs:schema elements MAY have a dfdl:format annotation (but
only one)
2. The top level xs:schema format annotation provides defaults for the
dfdl properties for every DFDL-annotatable construct in the schema
document.
(update 1) They do not apply to any constructs in included/imported schema
which may have their own defaults
3. local dfdl annotations on a construct of the schema take precedence
over properties coming from the lexically enclosing top-level schema
format annotation (if there is one)
4. when a property binding appears explicitly on a reference (element,
type, or group), the same property binding cannot appear explicitly on the
referenced global definition or declaration. (Schema definition error)
5. The merged explicitly defined properties from the reference and
declaration/definition take precedence over the defaults applied to the
declaration/definition, which take precedence over the defaults applied to
the reference.
6. The same precedence rules apply to simpleType inheritance
7. There are no dfdl annotations on xs:complexTypes and xs:group
declarations
8 Variables can still be used for 'parameterization' but expected to be
the exception.
Splitting dfdl:element and dfdl:simpleType properties.
SH proposed that the dfdl:properties on an xs:element and xs:simpleType,
currently are nearly the same should be separated so that as far as
possible the representational properties are on the xs:simpleType and only
the instance properties are on the xs:element. That is become more type
oriented similar to XML schema. After discussion of the details,
particularly where dfdl:length would be allowed we decided delay any
decision until next week. It was noted that it will not be possible to
change later.
(update 1) The split also applies to xs:element and xs:complexType which
would make xs:simpleTypes and xs:complexTypes symmetrical.
045: Resolving points of uncertainty
An updated proposal was distributed and comments received. The comment
were largely editorial and will be incorporated into the next version.
AOB:
Draft 36 was made available but proplems with gridforge prevented it being
uploaded. Contact Alan Powell for a copy.
Next call 14 October 13:00 UK for 2 hours
Meeting closed, 15:05
Actions raised at this meeting
No
Action
060
Should dfdl become more type oriented and split dfdl:properties between
element and simpleType/complexType
Current Actions:
No
Action
012
AP/SH: Update decimalCalendarScheme
10/9: Not allocated yet
17/9: No update
24/9: Add calendar binary formats to actions
22/10: No progress
16/1: proposal distributed and discussed. Will be redistributed
21/1: add locale,
04/02: changed from locale to specific properties
18/2: Need more investigation of ICU strict/lax behaviour.
08/04: Not discussed
22/04: AP to complete asap once the ICU strict/lax behaviour is
understood.
29/04: No progress
06/05: No progress
13/05: Calendar has been added to latest spec version v034 but still a few
details to clarify.
20/05: No Progress
27/05: No Progress
03/06: No Progress (low priority)
09/06: No Progress (low priority)
17/06: SH to check ICU code for lax calendar behaviour
24/06: no progress
01/07: no progress
15/07: no progress
29/07: no progress
05/08: no progress
12/08: no progress
19/08: Inconsistencies are being found in ICU behaviour so Calendars need
reviewing again.
26/08: Specific three character short time zones may not be maintained
during round tripping when there is more than one short form for a time
zone offset. Because dates and datetimes in the infoset only maintain a
time zone offset so on unparsing it isn't possible to say which short form
will be selected for a particular offset when there is more than one
possible. Need to document.
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
033
AP/TK: Assert/Discriminator semantics. AP to document. TK to check uses of
discriminator besides choice.
08/04: In progress within IBM
22/04: Waiting for TK to return from leave to complete.
29/04: TK has sent examples shown need for discriminators beyond choice.
Agreed. MB to respond to TK
06/05: Discussed suggestion of adding type indicator to discriminator. MB
to provide examples.
15/03: Semantic documented in v034. MB to provide examples of need for
scope indicator on discriminator
20/05: MB to provide examples of need for scope indicator on discriminator
(but lower priority than action 029)
27/05: No Progress (lower priority)
....
19/08: No Progress (lower priority)
26/08: No Progress (lower priority)
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
037
All: Approach for XML Schema 1.0 UPA checks.
22/04: Several non-XML models, when expressed in their most obvious DFDL
Schema form, would fail XML Schema 1.0 Unique Particle Attribution checks
that police model ambiguity. And even re-jigging the model sometimes
fails to fix this. Note this is equally applicable to XMl Schema 1.1 and
1.0. While the DFDL parser/unparser can happily resolve the ambiguities,
the issue is one of definition. If an XSD editor that implements UPA
checks is used to create DFDL Schema, then errors will be flagged. DFDL
may have to adopt the position that:
a)DFDL parser/unparser will not implement some/all UPA checks (exact
checks tbd)
b) XML Schema editors that implement UPA checks will not be suitable for
all DFDL models
c) If DFDL annotations are removed, the resulting pure XSD will not always
be valid (ie, the equivalent XML is ambiguous and can't be modelled by XML
Schema 1.0)
Ongoing in case another solution can be found.
29/04: Will ask DG and S Gao for opinion before closing
06/05: Discussed S Gao email and suggestions. Decided need to review all
XML UPA rules and decide which apply to dfdl.
20/05: SH or SKK to investigate
27/05: No Progress
03/06: The concern is that some dfdl schemas will fail UPA check when
validation is turned on or when editted using tooling that enforces UPA
checks. Renaming fields will resolve some/most issues. Need documentation
that describes issue and best practice.
17/06: no change
24/06: no change
01/07: no prgress
15/07: No Progress (lower priority)
29/07: No Progress (lower priority)
05/08: No Progress (lower priority)
12/08: No Progress (lower priority)
19/08: Clarify that this action is to go through the XML UPA checks to
assess impact on dfdl schemas and advice best practice. Name clashes is
just one example. SH or SKK
26/08: No Progress (lower priority)
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
045
20/05 AP: Speculative Parsing
27/05: Psuedo code has been circulated. Review for next call
03/06: Comments received and will be incorporated
09/06: Progress but not discussed
17/06: Discussed briefly
24/06: No Progress
01/07: No Progress
15/07: No progress. MB not happy with the way the algorithm is documented,
need to find a better way.
29/07: No Progress
05/08: No Progress. Will document behaviour as a set of rules.
12/08: No Progress
19/08: No Progress
26/08: No Progress
09/09: no progress
16/09: no progress
30/09: AP distributed proposal and others commented. Brief discussion AP
to incorporate update and reissue
07/10: Updated proposal was discussed.Comments will be incorporated into
the next version.
049
20/05 AP Built-in specification description and schemas
03/06: not discussed
24/06: No Progress
24/06: No Progress (hope to get these from test cases)
15/07: No progress. Once available, the examples in the spec should use
the dfdl:defineFormat annotations they provide.
.....
19/08: No Progress (lower priority)
26/08: No Progress (lower priority)
09/09: no progress
30/09: no progress
07/10: no progress
051
Scoping rules.
MB: to document change to scoping rules to satisfy implementation concerns
17/06: MB and SH proposals discussed. Needs further discussion
24/06: AP to update presentation with latest proosal
24/06: AP had updated presentation. MB to review
08/07: Discussed at length. Simple types will now take annotations.
Variables will be used for parameters.
15/07: No further progress. Needs final write up.
29/07: No Progress
05/08: No Progress
12/08: No Progress
19/08: AP will document new syntax rules.
26/08: No Progress
09/09: AP has documented new scoping rules. Not discussed
16/09: Not disussed. AP to update element reference examples
30/09: Significant dissatisfaction with proposed new rules. New proposal
developed during call. AP to document.
07/10: New proposal was refind. Details in minutes.
054
ICU DecimalNumber/ Calendar behaviour
15/07: No progress
29/07: No Progress.
05/08: No Progress. This action is to discover and document ICU behaviour.
DFDL will do whatever ICU does.
12/08: No Progress
19/09: More examples of inconsistent behaviour discovered
09/09: no progress
16/09: no progress
30/09: no progress
07/10: no progress
056
resolve lenghtUnit=bits including fillbytes
12/08: No Progress
19/08: No Progress
26/08: No Progress
09/09: no progress
30/09: no progress
07/10: no progress
059
9/9: define how encoding, byteorder and floating point format externally
16/09: no progress
07/10: no progress
060
Should dfdl bcome more type oriented and split dfdl:properties between
eleement and simpleType/complexType
Closed actions:
057
Decide semantics and enumeration for 'parsed' occursCountKind
26/08: Subsequent discussion agreed on 'parsed' Need to agree semantics
09/09: no progress
16/09: occursxxx applies to array and optional elements. occursCountKind
enumeration agreed. Semantics of 'parsed' are 'parse as many as possible.
30/09: Closed
Work items:
No
Item
target version
status
003
Variables (from action 042)
036
done
005
Improvements on property descriptions
not started
006
Envelopes and Payloads (from action 026)
036
done
007
valueCalc (from action 029)
036
done
011
How speculative parsing works (combining choice and variable-occurence -
currently these are separate) (from action 045)
awaiting completion of actions 045
012
Reordering the properties discussion: move representation earlier, improve
flow of topics
not started
033
Numeric data - what physical reps are allowed for what logical types (from
action 020)
036
ensure all behaviour documented
036
Update dfdl schema with change properties
038
Improve length section including bit handling
some improvement in 036
042
Mapping of the DFDL infoset to XDM
not required for V1 specification
051
Revised scoping rules (from action 051)
036
awaiting completion of action 051
052
add entity for 'one or more white space characters'
036
done
053
name, baseFormat, selector, escapeSchemeRef, textNumberFormatRef,
textCalendarFormatRef, binaryCalendarFormatRef attributes only
036
done
054
Add occureCountKind='parsed'
036
done
055
Make dfdl:initiatedConet discriminating (from action 58)
036
done
056
bidi support (action 044)
036
done
057
Properties that take an expression (action 55)
036
done
058
textPadCharacter %#rxx limitation and split to textxxxxPadCharacter
059
limit terminatorCanBeMissing to last element in schema. Ignore elsewhere.
060
Alan Powell
MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM email: alan_powell(a)uk.ibm.com
Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898
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IBM United Kingdom Limited - Registered in England and Wales with number
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