Open Grid Forum: Data Format Description Language Working Group
OGF DFDL Working Group Calls, July 7-8 2009
Meeting opened, 14:00 UK
Attendees
Mike Beckerle (Oco)
Alan Powell (IBM)
Peter Lambros (IBM)
Steve Hanson (IBM)
Apologies
Suman Kalia (IBM)
Agenda:
Action 042 Variables.
The uses cases for variables refined to
Variable markup - set once from document content (typically near start of
document)
Variable markup - set (possibly multiple times) based on first usage (eg
first instance of separator determines separator character used)
Values set externally - eg encoding, byteorder
Parameterization of global entity - parameter set as fixed value or as
expression
Envelope/payload - payload markup/discriminator set by value(s) in
envelope
Proposal:
Variables defined at schema level
A dfdl:variable annotation to create an new instance of a variable. for
example dfdl:variable ref=var1.
dfdl:set variable to set a value once
existing $var to refer to variables.
The scope of a variable is where the instance is created.
New instance of a variable hides a previous variable of the same name.
PL documenting
Action 051 Scoping rules.
Simple Types
Further discussion of last weeks recommendation that dfdl annotations
should not be allowed on simpleTypes.
Noted that the current scoping rule of the properties on the element
taking precedence over properties on the simpleType effectively meant the
simpleType properties were ignored as the element would pick up all
properties from scope.
It was decided that
DFDL annotaions will be allowed on simpleTypes
The properties on the element and the referenced simpleType will be merged
. It is a schema definition error if the same property is explicitly
specific on both the element and simpleType.
Global simpleTypes should not be validated.
Parameterization
Continued to investigate using variable for parameterization. Decided
variables, parameters and properties were very similar.
Proposal: Still use variables for parameterization (see above)
AOB
There will be 1 calls next week
Next call 15th July 14:00 UK Scheduled for 2 hours
Meeting closed, 15:00 UK
Actions raised at this meeting
No
Action
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
026
SH: Envelopes and Payloads
08/04: Not discussed explicity, but recursive use of DFDL is tied up with
this
22/04: Two aspects. Firstly compositional - do sufficient mechanisms exist
to model an envelope with a payload that varies. Secondly markup syntax -
this might be defined in the envelope.
The second of these is very much tied up with the variable markup action
028, so will be considered there. SH to verify the composition aspect.
29/04: SH and AP working on proposal. related to Action 028
06/05: No progress
06/05: No progress
20/05: No Progress
27/05: Still a number of aspects to be decided.
- Compostion - Does the envelope and payload need to be defined in the
same schema or should they be dynamically bound at runtime?
- Compostion- How is a variable payload specified. Choice or xs:any; New
action raised to discuss xs:any
- extracting dymanic syntax from data. Covered by action 029 valuecalc.
03/06: Dynamic runtime binding will not be supported.
SH investigating use of variables to enable standalone and use in envelope
of global element.
09/06: Payload should be specified using a choice rather than xs:any
17/06: SH still working on example using variables
24/06: SH to document how property list satisfies uses cases.
01/07: SH to document how property list satisfies uses cases. PL looking
at variable also. MB suggested modelling first separator as data for use
case 3.
029
MB: valueCalc (output length calculation)
08/04: Not discussed
22/04: Action allocated to MB, this is to complete the work started at the
Hursley WG F2F meeting.
29/04: No progress
06/05: MB will have update for next call
13/05: MB will have update for next call
20/05: Some progress. will be circulated this week
27/05: MB circulated proposal and got comments. Will update and review on
next call
03/06: Discussed proposal. MB to update dealing with uses cases raised.
Options include a new lenghtKind='Reference' to make it easier to
distinguish from fixed length case. Or use outputLengthCalc to separate
calculation of parsing and unparsing length.
09/06: SH/AP proposal discussed and MB to document
17/06: MB to document proposal.
Grammar updated and reviewed. Minor changes needed.
24/06: Grammar description was updated and approved. Need to describe new
function.
01/07: MB to circulate grammar and document new XPATH function
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)
03/06: No Progress (lower priority)
09/06: No Progress (lower priority)
24/06: No Progress (lower priority)
01/07: No Progress (lower priority)
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
038
MB: Submit response to OMG RFI for non-XML standardization
22/04: First step is for MB to mail the OGF Data Area chair to say that we
want to submit
29/04: MB has been in contact with OMG and will sunbit dfdl.
06/05: MB has prepared response to OMG. Will send DFDL sepc v033
20/05: Response has been sent to OMG based on v034
27/05: Awaiting response from OMG.
03/06: On hold
042
MB: Complete variable specification.
To include how properties such as encoding can be set externally. Must be
a known variable name.
06/05: No progress
20/05: AP to make proposal
27/05: MB proposed differentiating between input and output variables to
avoid unnecessary evaluations during parse and unparse. Need to complete
rest of variable specification.
03/06: Pointed out problem of declaring variables input or output when
used to define syntax which is used both times. MB to update proposal to
include how variables are set externally and how specific properties such
as encoding are set.
09/06: SKK to use example to dicument his proposal
17/06: SKK to refine proposal. Other aspects need progress.
24/06: SKK proposal discussed but not accepted. PL to document simpler
proposal.
07/01: PL working on proposal
044
13/05: Bidi
20/05: AP: will check what IBM products support.
27/05: Bidi is supported so will be needed in dfdl v1
03/06: No Progress
09/06: No Progress
24/06: No Progress
01/07: AP started investigation and documented issues. Suggest do whatever
XML does.
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
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)
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
054
ICU DecimalNumber behaviour
Closed actions:
027
SH: Property precedence tables
08/04: Not discussed
22/04: Two things missing from the existing precedence trees. Firstly,
does not show alternates (eg, initiator v initiatorkind). Secondly, need a
tree per concrete DFDL object (eg, element). SH to update.
29/04: No progress
06/05: SH is updating tables which will be ready for next call
13/05: SH emailed updated version. AP commented.. See minutes for issues
and property changes.
20/05: Updated version circulated. Review before next call and be ready
for vote.
27/05: Updated version circulated. more comments raised.
03/06: Further updates to clarify 'core'. Also identified missing design
for outputMinLength
17/06: Being updated to include outputMinlength
24/06: Table now in maintenance mode. Move to work item
01/07: closed
052
Discriminator timing property
24/06: Need to add timing property to discriminator
24/06: Agreed. Should default to after. Closed
053
poistion() function
24/06: agreed to add
24/06: Agreed. Closed
Work items:
No
Item
target version
status
003
Variables - ??, 2008 (Mike)
005
Improvements on property descriptions - ??, 2008 (All - split TBD)
006
Envelopes and Payloads (Steve) - Apr 30, 2008
007
(from draft 32) valueCalc (Mike) - ??, 2008
008
(from draft 32) Property precedence for writing (Steve) -
done up to v35
009
(from draft 32) Variable markup (Steve) - Mar 31, 2008 (deferred)
ignoreCase added
035
done
011
(from draft 32) How speculative parsing works (combining choice and
variable-occurence - currently these are separate) ??, 2008 (IBM)
in progress
012
(from draft 32) Reordering the properties discussion: move representation
earlier, improve flow of topics ??, 2008 (Alan)
not started
027
Calendar schemes
035
done
032
Floating components
035
done
033
Changes from action 020 and 027 - renaming properties etc
binNumberCheckPolicy
035
done
035
Remove unorderedInitiated, add initiated content (a041)
035
done
036
Update dfdl schema with change properties (Suman)
037
Infoset text codepage
035
done
038
Improve length section
039
Change scoping of simple types (A 046)
035
replace by new scoping rules
040
Document outputMinLength (A027)
035
done
042
mapping of the dfdl infoset to XDM
Not required for V1 specification
043
Document infoset data types (A043)
035
need to add logical to physical mapping
044
non-format scoping rules (A047)
035
done
045
Defer unresolvable choice.
035
done
046
Document properties for syntax ignore case, etc alternative to variable
markup
035
done
047
Remove xs:any
035
done
048
Keep precedence tables up to date (SH)
035
done
049
Discriminator timing attribute
035
done
050
position() function
035
done
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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