Mike
I have added this to the spec doc with
some minor changes shown in attached.
Two new questions
- I assume in/outvalueCalc are
not allow on arrays
- dfdl:hidden prevents elements
appearing in the infoset on parsing but there isn't an equivalent to prevent
infoset elements appearing in the data stream on unparsing. We have assumed
that inputvalueCalc prevents output but is that always the case? (Steve
you need to add InputValueCalc to unparsing property precedence). If inputValueCalc
is sufficient to prevent output couldn't outputvalueCalc prevent input
rather than hidden?
Alan Powell
MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM email: alan_powell@uk.ibm.com
Tel: +44 (0)1962 815073
Fax: +44 (0)1962 816898
| From:
| "Mike Beckerle" <mbeckerle.dfdl@gmail.com>
|
| To:
| Steve Hanson/UK/IBM@IBMGB
|
| Cc:
| dfdl-wg@ogf.org
|
| Date:
| 09/04/2008 15:03
|
| Subject:
| Re: [DFDL-WG] DFDL: Calculated Values
section rewrite |
Hmm. We’re in this situation
where DFDL is so rich with features that anything those features don’t
handle will by definition be an obscure corner case thereby hard to motivate.
I can change this example to
use three single byte binary integers instead of 6 packed decimal digits.
This is certainly a feasible binary data format, though it’s nothing I’ve
ever seen. It also makes the example orthogonal to the decimal changes,
so generally is more on point.
Attachment is new example plus
the other improvements suggested.
From: Steve Hanson [mailto:smh@uk.ibm.com]
Sent: Wednesday, April 09, 2008 9:29 AM
To: mbeckerle.dfdl@gmail.com
Cc: dfdl-wg@ogf.org
Subject: Re: [DFDL-WG] DFDL: Calculated Values section rewrite
Comments from Ian and Steve:
1) Is it a schema error if default/fixed attributes specified along with
dfdl:inputValueCalc and/or dfdl:outputValueCalc?
2) 2D array.
- dfdl:occurrences() is not in the expression language in draft 031. Is
something missing from the language, or should the XPath count() function
be used here?
- $dfdl:occurrences - $ not needed
- dfdl:outputValueCalc for 'ncols' - we think the else clause should be
'..\rows[1]\cols'
3) PD date
- As an example, it's perhaps not a good one as we have decimalCalendarFormat
as a property of a decimal number, which is intended to do exactly this
- As it stands, it will need updating to reflect latest decimal supplement
Regards, Steve
Steve Hanson
Programming Model Architect
WebSphere Message Brokers
Hursley, UK
Internet: smh@uk.ibm.com
Phone (+44)/(0) 1962-815848
"Mike Beckerle"
<mbeckerle.dfdl@gmail.com>
Sent by: dfdl-wg-bounces@ogf.org
09/04/2008 02:44
|
Please respond to
mbeckerle.dfdl@gmail.com |
|
|
To
| Alan Powell/UK/IBM@IBMGB
|
|
cc
| dfdl-wg@ogf.org, dfdl-wg-bounces@ogf.org
|
|
Subject
| Re: [DFDL-WG] DFDL: Calculated Values
section rewrite |
|
I’ve attached a revised calculated value properties doc which incorporates
suggestions from Alan, specifically, there’s a new example, which is a
2-d array with nrows, ncols fields stored before it. I think this motivates
the connection between outputValueCalc, and number of occurrences and occurs
calculations nicely.
…mikeb
From: Alan Powell [mailto:alan_powell@uk.ibm.com]
Sent: Thursday, March 27, 2008 2:02 PM
To: mbeckerle.dfdl@gmail.com
Cc: dfdl-wg@ogf.org; dfdl-wg-bounces@ogf.org
Subject: Re: [DFDL-WG] DFDL: Calculated Values section rewrite
Mike
A couple of comments on the using derived/representation nomenclature with
OutputValueCalc and a couple of minor corrections.
However I thought the Length Prefix example a bit odd as I would have expected
a single HexBinary element rather than an array of bytes.
Alan Powell
MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM email: alan_powell@uk.ibm.com
Tel: +44 (0)1962 815073
Fax: +44 (0)1962 816898
| From:
| "Mike Beckerle"
<mbeckerle.dfdl@gmail.com>
|
| To:
| <dfdl-wg@ogf.org>
|
| Date:
| 26/03/2008 16:39
|
| Subject:
| [DFDL-WG] DFDL: Calculated Values section
rewrite |
My deliverable for the next draft (32) was to revise the calculated values
section.
I have rewritten it and the draft is attached.
Of note: I have removed the troublesome “outputLengthCalc” property,
as I no longer see a critical need for it. One of the examples computes
the number of occurrences for a byte array, and I think that mechanism
along with alignment is sufficient to handle the troublesome cases I was
considering where size of padding had to be dynamically computed.
The section now consists of a short table of definition, followed by illustrative
examples, however, I think this is fine. The semantics of inputValueCalc
and outputValueCalc aren’t really that complex. They can be described
in a paragraph. It is the motivation for them that is complicated, so I
think examples in the spec, while sometimes considered problematic, are
OK in this case.
[attachment "calculated-value-properties.doc" deleted by Alan
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