[DFDL-WG] DFDL OGF WG call - Action 020
Steve Hanson
smh at uk.ibm.com
Wed Jan 28 08:03:13 CST 2009
Action 020:
020
SH: Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy
22/10: No progress
10/12: added how to decide to overpunch and sign position
a) Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy
Add new property to section 15.4 Properties Specific to Number with Binary
representation.
binaryNumberCheckPolicy
Enum
Values are ?strict? and ?lax?.
Indicates how lenient to be when parsing binary numbers.
If ?lax? then the parser tolerates all valid alternatives where such
alternatives exist. Specifically, for binaryNumberRepresentation =
'packed' the sign nibble for positive, negative, unsigned and zero is
allowed to be any of the valid respective values.
On unparsing, the specified value is always used.
Also suggest changing some of the other property names in 15.4:
"decimalVirtualPoint" -> "binaryDecimalVirtualPoint"
"packedDecimalSignCodes" -> "binaryPackedSignCodes"
And changing binaryNumberRepresentation enumeration:
"BCD" -> "bcd"
b) Zoned decimals: How to decide to overpunch and sign position
Spec assumes that overpunching of the rightmost character always takes
place. IBM architecture allows no overpunching (ie, Fx instead of Cx/Dx) -
this is supported by IBM MRM & WTX parsers. Additionally IBM MRM parser
allows separate sign byte, and sign byte on left. Let's deal with these
separately:
i) No overpunching.
The IBM architecture allows the rightmost byte to have a zone (Fx) or a
sign (Cx/Dx) as the left nibble. I don't see why we can't base what to
expect when parsing, and output when unparsing, on the logical xsd type.
- If it is an unsigned type then DFDL expects the rightmost byte to have a
zone nibble when parsing, and outputs a zone nibble when unparsing.
- If it is a signed type then DFDL expects it to have a sign nibble when
parsing, and outputs a sign nibble when unparsing.
For analogy with DFDL packed decimals, it seems at first glance that we
should also extend the numberCheckPolicy 'lax' setting to treat a zone
nibble as a +ve sign nibble for a signed type. However, IBM iSeries always
outputs Fx to mean +ve but accepts both Fx & Cx on input. It is perhaps
better therefore that DFDL always tolerates Fx when parsing a signed zoned
decimal, otherwise iSeries users would always have to set
numberCheckPolicy to 'lax', which might have other implications in the
future.
ii) Separate sign byte.
I don't believe the IBM architecture allows this. I'm not sure where MRM
got this from. I don't think DFDL needs to support it.
iii) Sign byte on left.
I don't believe the IBM architecture allows this. I'm not sure where MRM
got this from. I don't think DFDL needs to support it.
Conclusion: No new DFDL properties needed, but words need adding to
explain zoned parse/unparse behaviour better.
Also suggest changing property names:
"zonedDecimalSignStyle" -> "numberZonedSignStyle"
"zeroNumberRep" -> "numberZeroRep"
Should also make clear that any explicit negative pattern in numberPattern
will be ignored if the xsd type is unsigned. (We could make this an error
but it precludes creation of a textNumberFormat that works with both
signed and unsigned types, plus pattern "##0.0" implictly is equivalent
to "##0.0;(##0.0)" ).
Regards
Steve Hanson
Programming Model Architect
WebSphere Message Brokers
Hursley, UK
Internet: smh at uk.ibm.com
Phone (+44)/(0) 1962-815848
Alan Powell/UK/IBM at IBMGB
Sent by: dfdl-wg-bounces at ogf.org
23/01/2009 13:36
To
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Subject
[DFDL-WG] DFDL: Minutes from OGF WG call, 21 January 2009
Open Grid Forum: Data Format Description Language Working Group
Weekly Working Group Conference Call
14:00 GMT, 21 January 2009
Attendees
Alan Powell (IBM)
Mike Beckerle(Oco)
Apologies
Steve Hanson (IBM)
1. XSD 1.1
Deferred to next call
2. Calendar formats
Discussed updated (v4) supplement emailed by AP
Agreed millisec/secSinceEpoc cannot be implied by length of logical data
so need seperate enumerations. Observed that these options were really
combination of 3 properties binary, length and sec/millisec. Suggested
renaming to binarySeconds and binaryMilliseconds
Packed calendars: decided that need to be able to specify at least the
packedDecimalSignCodes property rather than assuming a default so
reference will be added to calendar description
Locale needs to be specified for numberformats and calendarFormats
(didn't identify any other areas) as it modifies the behaviour of ICU.
Decided to add locale to numberFormat and CalendarFormat
3. Escape Schemes
Agreed need for multiple escape delimiter pairs but not nested.
Need an escape for escape character even though in most cases this will be
the same character, eg /n //, There are some formats that have a different
escape, eg /n &/. Only need single escape characters and one level of
escape characters.
Discussed how to deal with comments of the form /* comment */ where
the escape delimiters are also the initiator and terminator of the field.
Semantic needed is 'only look for field terminator not any parent
terminator or any other syntax elements'. May fall out naturally from the
speculative parsing rules. Need further discussion.
4. AOB
Next call 28 January 14:00
Meeting closed, 15:00 GMT
Actions raised at this meeting
No
Action
031
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,
020
SH: Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy
22/10: No progress
10/12: added how to decide to overpunch and sign position
023
MB: Review Schema 1.1
024
String XML type
025
Escape schemes
21/1: discussed requirements
026
SH: Envelopes and Payloads
027
Property precedence tables
028
Variable markup
029
valueCalc (output length calculation)
030
AP: confirm with WTX that can drop duration
21/6: WTX confirm that they do not have a duration type so do not need it
in dfdl. Will drop from spec. Closed
Closed actions:
030
AP: confirm with WTX that can drop duration
21/6: WTX confirm that they do not have a duration type so do not need it
in dfdl. Will drop from spec. Closed
034 Work items:
No
Item
001
String XML type (Ian P) - Apr 30, 2008
002
Escape schemes (Ian P) - Apr 30, 2008
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
mostly
complete
008
(from draft 32) Property precedence for writing (Steve) -
under review
009
(from draft 32) Variable markup (Steve) - Mar 31, 2008
proposal needs writing up
010
(from draft 32) Assertions, discriminators and choice, including
discussion of timing option (Suman) - Mar 31, 2008 * in progress *
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 *
025
Augmented infoset and unparsing (Alan)
added but needs work
complete - specification updated
Alan Powell
MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM email: alan_powell at uk.ibm.com
Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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