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> 09/04/2008 02:44
|
|
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
Powell/UK/IBM] --
dfdl-wg mailing list
dfdl-wg@ogf.org
http://www.ogf.org/mailman/listinfo/dfdl-wg
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
--
dfdl-wg mailing list
dfdl-wg@ogf.org
http://www.ogf.org/mailman/listinfo/dfdl-wg
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